The first industry-specific estimates of annual water use in nearly 30 years yield some surprising findings.

Getting to a low-carbon economy means going back to the future.

The cost associated with ISO 14001 certification has developing countries companies’ lag in environmental management.

Carbon emissions from industry are dominated by production of goods in steel, cement, plastic, paper, and aluminum. Demand for these materials is anticipated to double at least by 2050, by which time global carbon emissions must be reduced by at least 50%. To evaluate the challenge of meeting this target, the global flows of these materials and their associated emissions are projected to 2050 under five technical scenarios. A reference scenario includes all existing and emerging efficiency measures but cannot provide sufficient reduction. The application of carbon sequestration to primary production proves to be sufficient only for cement. The emissions target can always be met by reducing demand, for instance through product life extension, material substitution, or “light-weighting”. Reusing components shows significant potential particularly within construction. Radical process innovation may also be possible. The results show that the first two strategies, based on increasing primary production, cannot achieve the required emissions reductions, so should be balanced by the vigorous pursuit of material efficiency to allow provision of increased material services with reduced primary production.

The generation and distribution of electricity comprises nearly 40% of U.S. CO₂ emissions, as well as large shares of SO₂, NO_x, small particulates, and other toxins. Thus, correctly accounting for these electricity-related environmental releases is of great importance in life cycle assessment of products and processes. Unfortunately, there is no agreed-upon protocol for accounting for the environmental emissions associated with electricity, as well as significant uncertainty in the estimates. Here, we explore the limits of current knowledge about grid electricity in LCA and carbon footprinting for the U.S. electrical grid, and show that differences in standards, protocols, and reporting organizations can lead to important differences in estimates of CO₂, SO₂, and NO_x emissions factors. We find a considerable divergence in published values for grid emissions factor in the U.S. We discuss the implications of this divergence and list recommendations for a standardized approach to accounting for air pollution emissions in life cycle assessment and policy analyses in a world with incomplete and uncertain information.

A hybrid life cycle-based trans-boundary greenhouse gas (GHG) emissions footprint is elucidated at the city-scale and evaluated for 8 US cities. The method incorporates end-uses of energy within city boundaries, plus cross-boundary demand for airline/freight transport and embodied energy of four key urban materials [food, water, energy (fuels), and shelter (cement)], essential for life in all cities. These cross-boundary activities contributed 47% on average more than the in-boundary GHG contributions traditionally reported for cities, indicating significant truncation at city boundaries of GHG emissions associated with urban activities. Incorporating cross-boundary contributions created convergence in per capita GHG emissions from the city-scale (average 23.7 mt-CO₂e/capita) to the national-scale (24.5 mt-CO₂e/capita), suggesting that six key cross-boundary activities may suffice to yield a holistic GHG emission footprint for cities, with important policy ramifications. Average GHG contributions from various human activity sectors include buildings/facilities energy use (47.1%), regional surface transport (20.8%), food production (14.7%), transport fuel production (6.4%), airline transport (4.8%), long-distance freight trucking (2.8%), cement production (2.2%), and water/wastewater/waste processing (1.3%). Energy-, travel-, and key materials-consumption efficiency metrics are elucidated in these sectors; these consumption metrics are observed to be largely similar across the eight U.S. cities and consistent with national/regional averages.

Carbonaceous aerosol concentrations and sources were compared during a yearlong study at two sites in East and West Jerusalem that were separated by a distance of approximately 4 km. One in six day 24-h PM_2.5 elemental and organic carbon concentrations were measured, along with monthly average concentrations of particle-phase organic compound tracers for primary and secondary organic aerosol sources. Tracer compounds were used in a chemical mass balance (CMB) model to determine primary and secondary source contributions to organic carbon. The East Jerusalem sampling site at Al Quds University experienced higher concentrations of organic carbon (OC) and elemental carbon (EC) compared to the West Jerusalem site at Hebrew University. The annual average concentrations of OC and EC at the East Jerusalem site were 5.20 and 2.19 μg m⁻³, respectively, and at the West Jerusalem site were 4.03 and 1.14 μg m⁻³, respectively. Concentrations and trends of secondary organic aerosol and vegetative detritus were similar at both sites, but large differences were observed in the concentrations of organic aerosol from fossil fuel combustion and biomass burning, which was the cause of the large differences in OC and EC concentrations observed at the two sites.

Antidepressant pharmaceuticals are widely prescribed in the United States; release of municipal wastewater effluent is a primary route introducing them to aquatic environments, where little is known about their distribution and fate. Water, bed sediment, and brain tissue from native white suckers (Catostomus commersoni) were collected upstream and at points progressively downstream from outfalls discharging to two effluent-impacted streams, Boulder Creek (Colorado) and Fourmile Creek (Iowa). A liquid chromatography/tandem mass spectrometry method was used to quantify antidepressants, including fluoxetine, norfluoxetine (degradate), sertraline, norsertraline (degradate), paroxetine, citalopram, fluvoxamine, duloxetine, venlafaxine, and bupropion in all three sample matrices. Antidepressants were not present above the limit of quantitation in water samples upstream from the effluent outfalls but were present at points downstream at ng/L concentrations, even at the farthest downstream sampling site 8.4 km downstream from the outfall. The antidepressants with the highest measured concentrations in both streams were venlafaxine, bupropion, and citalopram and typically were observed at concentrations of at least an order of magnitude greater than the more commonly investigated antidepressants fluoxetine and sertraline. Concentrations of antidepressants in bed sediment were measured at ng/g levels; venlafaxine and fluoxetine were the predominant chemicals observed. Fluoxetine, sertraline, and their degradates were the principal antidepressants observed in fish brain tissue, typically at low ng/g concentrations. A qualitatively different antidepressant profile was observed in brain tissue compared to streamwater samples. This study documents that wastewater effluent can be a point source of antidepressants to stream ecosystems and that the qualitative composition of antidepressants in brain tissue from exposed fish differs substantially from the compositions observed in streamwater and sediment, suggesting selective uptake.

Carbon sequestration by forested ecosystems offers a potential climate change mitigation benefit. However, wildfire has the potential to reverse this benefit. In the western United States, climate change and land management practices have led to increases in wildfire intensity and size. One potential means of reducing carbon emissions from wildfire is the use of prescribed burning, which consumes less biomass and therefore releases less carbon to the atmosphere. This study uses a regional fire emissions model to estimate the potential reduction in fire emissions when prescribed burning is applied in dry, temperate forested systems of the western U.S. Daily carbon dioxide (CO₂) fire emissions for 2001−2008 were calculated for the western U.S. for two cases: a default wildfire case and one in which prescribed burning was applied. Wide-scale prescribed fire application can reduce CO₂ fire emissions for the western U.S. by 18−25% in the western U.S., and by as much as 60% in specific forest systems. Although this work does not address important considerations such as the feasibility of implementing wide-scale prescribed fire management or the cumulative emissions from repeated prescribed burning, it does provide constraints on potential carbon emission reductions when prescribed burning is used.

Environmentally persistent free radicals (EPFRs) have been shown to form on the surfaces of various types of transition metal-containing particulate matter (PM), and it has been demonstrated they are capable of initiating adverse health impacts. Following sonification and solvent extraction for chemical analysis, they are partially converted to molecular species. Alcoholic solvents extracted the EPFRs with near 100% efficiency, while nonpolar hydrocarbon solvents exhibited <20% efficiency and dichloromethane exhibited 20−55% efficiency. The extracted radicals reacted in solution to form multiple molecular reaction products including catechol, hydroquinone, phenol, chlorinated phenols, dibenzo-p-dioxin, and dibenzofuran. This suggests that EPFRs in environmental samples are indistinguishable from molecular pollutants and are subject to misidentification as molecular adsorbates when traditional extraction and chemical analysis methods are employed. On the basis of these findings, the origin of the toxicity of particulate matter contaminated with toxic organic compounds should be considered for re-evaluation to include the possibility that EPFRs may be a significant contributor, and the impact of some molecular pollutants may have been overestimated.

Tracer tests were performed in distinct biogeochemical zones of a sand and gravel aquifer in Cape Cod, MA, to study the redox chemistry (I) and transport (Cs, I) of cesium and iodine in a field setting. Injection of iodide (I⁻) into an oxic zone of the aquifer resulted in oxidation of I⁻ to molecular iodine (I₂) and iodate (IO₃⁻) over transport distances of several meters. Oxidation is attributed to Mn-oxides present in the sediment. Transport of injected IO₃⁻ and Cs⁺ was retarded in the mildly acidic oxic zone, with retardation factors of 1.6−1.8 for IO₃⁻ and 2.3−4.4 for Cs. Cs retardation was likely due to cation exchange reactions. Injection of IO₃⁻ into a Fe-reducing zone of the aquifer resulted in rapid and complete reduction to I⁻ within 3 m of transport. The nonconservative behavior of Cs and I observed during the tracer tests underscores the necessity of taking the redox chemistry of I as well as sorption properties of I species and Cs into account when predicting transport of radionuclides (e.g., ¹²⁹I and ¹³⁷Cs) in the environment.

Animal feeding operations (AFOs) and wastewater treatment plants (WWTPs) are potential sources of antibiotic resistance genes (ARGs) in rivers and/or antibiotics that may select for ARGs in native river bacteria. This study aimed to identify ARG distribution patterns that unambiguously distinguish putative sources of ARG from a native river environment. Such molecular signatures may then be used as tracers of specific anthropogenic sources. Three WWTPs, six AFO lagoons, and three sites along a pristine region of the Cache la Poudre (Poudre) River were compared with respect to the frequency of detection (FOD) of 11 sulfonamide and tetracycline ARGs. Principle-component and correspondence analyses aided in identifying the association of tet(H), tet(Q), tet(S), and tet(T) (tet group HQST) with AFO environments and tet(C), tet(E), and tet(O) (tet group CEO) with WWTPs. Discriminant analysis indicated that both tet group HQST and tet group CEO correctly classified the environments, but only the tet group HQST provided a significant difference in FOD among the environments (p < 0.05). Sul(I) was detected in 100% of the source environments but just once in the pristine Poudre River, which was dominated by tet(M) and tet(W). Tet(W) libraries generated from the pristine Poudre River, WWTPs, and AFO lagoons were also discernible based on restriction fragment length polymorphism and phylogenetic analysis. Thus, a novel approach was developed and demonstrated to be effective for the model river system, taking an important step in advancing the fundamental understanding of ARG transport in the environment.

Ship emissions contribute significantly to gaseous and particulate pollution worldwide. To better understand the impact of ship emissions on air quality, measurements of the size-resolved chemistry of individual particles in ship emissions were made at the Port of Los Angeles using real-time, single-particle mass spectrometry. Ship plumes were identified through a combination of ship position information and measurements of gases and aerosol particles at a site 500 m from the center of the main shipping channel at the Port of Los Angeles. Single particles containing mixtures of organic carbon, vanadium, and sulfate (OC-V-sulfate) resulted from residual fuel combustion (i.e., bunker fuel), whereas high quantities of fresh soot particles (when OC-V-sulfate particles were not present) represented distinct markers for plumes from distillate fuel combustion (i.e., diesel fuel) from ships as well as trucks in the port area. OC-V-sulfate particles from residual fuel combustion contained significantly higher levels of sulfate and sulfuric acid than plume particles containing no vanadium. These associations may be due to vanadium (or other metals such as iron) in the fuel catalyzing the oxidation of SO₂ to produce sulfate and sulfuric acid on these particles. Enhanced sulfate production on OC-V-sulfate ship emission particles would help explain some of the higher than expected sulfate levels measured in California compared to models based on emissions inventories and typical sulfate production pathways. Understanding the overall impact of ships emissions is critical for controlling regional air quality in the many populated coastal regions of the world.

There is a pressing need for information on the mobility of nanoparticles in the complex aqueous matrices found in realistic environmental conditions. We dispersed three different metal oxide nanoparticles (TiO₂, ZnO and CeO₂) in samples taken from eight different aqueous media associated with seawater, lagoon, river, and groundwater, and measured their electrophoretic mobility, state of aggregation, and rate of sedimentation. The electrophoretic mobility of the particles in a given aqueous media was dominated by the presence of natural organic matter (NOM) and ionic strength, and independent of pH. NOM adsorbed onto these nanoparticles significantly reduces their aggregation, stabilizing them under many conditions. The transition from reaction to diffusion limited aggregation occurs at an electrophoretic mobility from around −2 to −0.8 μm s⁻¹ V⁻¹ cm. These results are key for designing and interpreting nanoparticle ecotoxicity studies in various environmental conditions.

Tidal seawater inundation of coastal acid sulfate soils can generate Fe- and SO₄-reducing conditions in previously oxic-acidic sediments. This creates potential for mobilization of As during the redox transition. We explore the consequences for As by investigating the hydrology, porewater geochemistry, solid-phase speciation, and mineralogical partitioning of As across two tidal fringe toposequences. Seawater inundation induced a tidally controlled redox gradient. Maximum porewater As (∼400 μg/L) occurred in the shallow (<1 m), intertidal, redox transition zone between Fe-oxidizing and SO₄-reducing conditions. Primary mechanisms of As mobilization include the reduction of solid-phase As(V) to As(III), reductive dissolution of As(V)-bearing secondary Fe(III) minerals and competitive anion desorption. Porewater As concentrations decreased in the zone of contemporary pyrite reformation. Oscillating hydraulic gradients caused by tidal pumping promote upward advection of As and Fe²⁺-enriched porewater in the intertidal zone, leading to accumulation of As(V)-enriched Fe(III) (hydr)oxides at the oxic sediment−water interface. While this provides a natural reactive-Fe barrier, it does not completely retard the flux of porewater As to overtopping surface waters. Furthermore, the accumulated Fe minerals may be prone to future reductive dissolution. A conceptual model describing As hydro-geochemical coupling across an intertidal fringe is presented.

The relationship between the formation of chlorinated aromatic (aromatic-Cl) compounds and ferric chloride in the solid phase during a thermal process motivated us to study the chemical characteristics of iron in a model solid sample, a mixture of FeCl₃·6H₂O, activated carbon, and boron nitride, with increasing temperature. Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed drastic changes in the chemical form of amorphous iron, consistent with other analytical methods, such as X-ray diffraction using synchrotron radiation (SR-XRD) and Fourier-transform infrared (FT-IR) spectroscopy. Atomic-scale evidence of the chlorination of aromatic carbon was detected by Cl−K X-ray absorption near edge structure (XANES) spectroscopy. These results showed the thermal formation mechanism of aromatic-Cl compounds in the solid phase with ferric chloride. We attribute the formation of aromatic-Cl compounds to the chlorination of carbon, based on the oxychlorination reaction of FeCl₃ at temperatures in excess of ca. 300 °C, when the carbon matrix is activated by carbon gasification, catalyzed by Fe₂O₃, and surface oxygen complexes (SOC) generated by a catalytic cycle of FeCl₂ and FeOCl. Chemical changes of trace iron in a thermal process may offer the potential to generate aromatic-Cl compounds in the solid phase.

We have investigated the mechanism of Fe uptake by a toxic strain of the freshwater cyanobacterium Microcystis aeruginosa (PCC7806) with particular attention given to the effect of Fe(II) and Fe(III) transformation kinetics on Fe uptake. Chemiluminescence analysis revealed that M. aeruginosa produces extracellular superoxide (a moderate Fe reducing agent) at rates of 0.4−1.2 amol cell⁻¹ h⁻¹ depending on initial Fe concentration in the culture medium. Short-term assimilation assays using ⁵⁵Fe showed that reduction of Fe(III) in both organic and inorganic forms by cell-generated superoxide or ascorbate facilitated Fe uptake via formation of unchelated Fe(II), when Fe availability was low because of the use of the strong Fe chelator ethylenediaminetetraacetate (EDTA) as a ligand. In contrast, Fe reduction was unimportant for Fe uptake in the presence of low concentrations (≤100 μM) of the weak Fe-binding ligand citrate because of a high concentration of unchelated Fe(III), indicating that the contribution of reduction to Fe uptake depends on the nature of Fe binding and availability of unchelated Fe(III) in the external medium. A kinetic model incorporating uptake of both unchelated Fe(II) and Fe(III) and based on similar models developed for marine microalgae successfully described Fe uptake rates by M. aeruginosa PCC7806.

Decabromodiphenyl ethane (DBDPE) is a brominated flame retardant (BFR) used as a replacement for the structurally similar decabromodiphenyl ether (decaBDE), which is a regulated environmental contaminant of concern. DBDPE has been found in indoor dust, sewage sludge, sediment, and biota, but little is known about its occurrence and distribution in the environment. In this paper, sediment was analyzed from 11 isolated Swedish lakes and along a transect running from central Stockholm through the Stockholm archipelago to the Baltic Sea. DBDPE was present in all samples. In lake sediment, the levels ranged from 0.23 to 11 ng/g d.wt. and were very similar to the levels of decaBDE (0.48−11 ng/g d.wt.). Since the lakes have no known point sources of BFRs, their presence in the sediments provides evidence for long-range atmospheric transport and deposition. In the marine sediment, the DBDPE and decaBDE levels decreased by a factor of 20−50 over 40 km from the inner harbor to the outer archipelago. There the DBDPE and decaBDE levels were similar to the levels in nearby isolated lakes. The results indicate that contamination of the Swedish environment with DBDPE has already approached that of decaBDE, and that this contamination is primarily occurring via the atmosphere.

Mineral sorption/coprecipitation is thought to be a principal sequestration mechanism for radioactive ⁹⁰Sr and ¹³⁷Cs in sediments impacted by hyperalkaline, high-level radioactive waste (HLRW) at the DOE’s Hanford site. However, the long-term persistence of neo-formed, contaminant bearing phases after removal of the HLRW source is unknown. We subjected pristine Hanford sediments to hyperalkaline Na−Al−NO₃−OH solutions containing Sr, Cs, and I at 10⁻⁵, 10⁻⁵, and 10⁻⁷ molal, respectively, for 182 days with either <10 ppmv or 385 ppmv pCO₂. This resulted in the formation of feldspathoid minerals. We leached these weathered sediments with dilute, neutral-pH solutions. After 500 pore volumes (PVs), effluent Sr, Cs, NO₃, Al, Si, and pH reached a steady-state with concentrations elevated above those of feedwater. Reactive transport modeling suggests that even after 500 PV, Cs desorption can be explained by ion exchange reactions, whereas Sr desorption is best described by dissolution of Sr-substituted, neo-formed minerals. While, pCO₂ had no effect on Sr or Cs sorption, sediments weathered at <10 ppmv pCO₂ did desorb more Sr (66% vs 28%) and Cs (13% vs 8%) during leaching than those weathered at 385 ppmv pCO₂. Thus, the dissolution of neo-formed aluminosilicates may represent a long-term, low-level supply of ⁹⁰Sr at the Hanford site.

Lake sediments are frequently used to reconstruct the rate and magnitude of human impacts on the biogeochemical cycle of mercury (Hg). The vast majority of these studies rely on excess ²¹⁰Pb inventories in short cores to temporally constrain recent trends in Hg deposition, revealing an approximately 3-fold increase in Hg deposition since preindustrial times. However, the exhaustion of unsupported ²¹⁰Pb and the onset of widespread global Hg pollution converge temporally in the late 19th century, raising the possibility that preindustrial Hg fluxes are poorly constrained. Here, we combine ²¹⁰Pb and accelerator mass spectrometry (AMS) ¹⁴C dated lake sediment records from arctic and Andean lakes to assess the reliability of ²¹⁰Pb-derived chronologies in the estimation of preindustrial Hg fluxes. For all four studied lakes, relying on ²¹⁰Pb chronologies results in an overestimate of preindustrial Hg fluxes, because extrapolated basal ²¹⁰Pb sedimentation rates are systematically overestimated in comparison to accumulation models that include ¹⁴C dates. In the Andes, the use of ¹⁴C dates is critical toward assessing the full history of Hg pollution, which extends beyond the industrial era. In the Arctic, ¹⁴C dating suggests that Hg deposition may have increased >10-fold since the Industrial Revolution, rather than the commonly quoted 3-fold increase. The incorporation of ¹⁴C dates may therefore be necessary if accurate Hg flux histories are sought from oligotrophic lake sediments.

Thirty-four years of data from the Great Lakes Fish Monitoring Program (GLFMP) show significant changes in the behavior of most contaminants in lake trout over time consistent with changes in contaminant inputs following regulation and remediation. Polybrominated diphenyl ethers (PBDEs) show positive apparent first-order rate constants falling to near zero. Dieldrin shows relatively unchanging half-lives of around 10 years except in Lake Superior (∼25 years). Mirex, consistently detected only in Lake Ontario fish, shows a slow decrease until the 1990s, when remediation of a source site occurred, after which half-lives are 2−3 years. Half-lives of oxychlordane, polychlorinated biphenyls (PCBs), and dichloro-diphenyl-trichlorethane (DDT) and its metabolites were typically 3−6 years until the mid 1980s; since then, the newest data confirm half-lives are usually around 15−30 years. For PCBs, an increasing half-life is found in other media as well. Changes in food web structure, fishery dynamics, and climate undoubtedly affect concentrations but cannot explain observed long-term trends across several media. Concentrations of legacy contaminants in the Great Lakes are likely to continue to decline only slowly and pose a health concern for decades without identifying and containing remaining sources.

The cloud condensation nuclei concentrations predicted by global aerosol models are sensitive to how new particle formation in subgrid anthropogenic SO₂ plumes is parameterized. Using a state-of-the-art kinetic nucleation model, we carried out two case studies to investigate the large difference in the number concentrations of ultrafine particles observed in the plumes from the Horne smelter: one in the summer and the other in the winter. Our model predicted that particle number concentrations are in good agreement with observations for both cases, showing that particle formation in the Horne smelter plumes is dominated by binary homogeneous nucleation (BHN) in the winter case and by ion-mediated nucleation (IMN) in the summer case. Further sensitivity studies reveal significant diurnal and seasonal variations of sulfate particle formation in the anthropogenic SO₂ plume, mainly associated with corresponding variations of two key parameters: hydroxyl radical concentration ([OH]) and temperature. Nucleation in the plume is negligible at night because of very low [OH]. BHN is significant when [OH] is relatively high or temperature is relatively low, and it is generally limited to the fresh plumes (within ∼15 km from source), but it can generate very high concentrations of ultrafine particles (peak values as high as 10⁵−10⁶ cm⁻³) under favorable conditions. IMN generally dominates nucleation in the plume when [OH] is relatively low or temperature is relatively high, and it extends from fresh plume to more aged plume and produces 2−3 × 10⁴ cm⁻³ of nucleated particles. The implications of the results are discussed.

In acid-mine drainage and acid-sulfate soil environments, the cycling of Fe and As are often linked to the formation and fate of schwertmannite (Fe₈O₈(OH)_8−2x(SO₄)_x). When schwertmannite-rich material is subjected to near-neutral Fe(III)-reducing conditions (e.g., in reflooded acid-sulfate soils or mining-lake sediments), the resulting Fe(II) can catalyze transformation of schwertmannite to goethite. This work examines the effects of arsenic(V) and arsenic(III) on the Fe(II)-catalyzed transformation of schwertmannite and investigates the associated consequences of this mineral transformation for arsenic mobilization. A series of 9-day anoxic transformation experiments were conducted with synthetic schwertmannite and various additions of Fe(II), As(III), and As(V). X-ray diffraction (XRD) and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy demonstrated that, in the absence of Fe(II), schwertmannite persisted as the dominant mineral phase. Under arsenic-free conditions, 10 mM Fe(II) catalyzed rapid and complete transformation of schwertmannite to goethite. However, the magnitude of Fe(II)-catalyzed transformation decreased to 72% in the presence of 1 mM As(III) and to only 6% in the presence of 1 mM As(V). This partial Fe(II)-catalyzed transformation of As(III)-sorbed schwertmannite did not cause considerable As(III) desorption. In contrast, the formation of goethite via partial transformation of As(III)- and As(V)-sorbed schwertmannite significantly decreased arsenic mobilization under Fe(III)-reducing conditions. This implies that the Fe(II)-catalyzed transformation of schwertmannite to goethite may help to stabilize solid-phase arsenic and retard its subsequent release to groundwater.

This study investigates gypsum scaling and cleaning behavior in forward osmosis (FO). The results show that gypsum scaling in FO is almost fully reversible, with more than 96% recovery of permeate water flux following a water rinse without addition of chemical cleaning reagents. Parallel comparisons of fouling and cleaning were made between FO (without hydraulic pressure) and RO (under high hydraulic pressure) modes. The shape of the water flux decline curves during gypsum scaling is similar in the two modes, but the flux recovery in FO mode is higher than that in RO mode by about 10%. This behavior suggests that operating in FO mode may reduce the need for chemical cleaning. The role of membrane materials in controlling gypsum scaling and cleaning was investigated using cellulose acetate (CA) and polyamide (PA) membranes. Gypsum scaling of PA membranes causes more severe flux decline and is harder to clean than that of CA membranes. AFM force measurements were performed between a gypsum particle probe and the membrane surfaces to elucidate gypsum scaling mechanisms. Analysis of adhesion force data indicates that gypsum scaling of the PA membrane is dominated by heterogeneous/surface crystallization, while gypsum scaling of the CA membrane is dominated by bulk crystallization and subsequent particle deposition. This finding implies that membrane surface modification and new material development can be an effective strategy to mitigate membrane scaling.

Smog chamber experiments were conducted to investigate secondary organic aerosol (SOA) formation from photo-oxidation of low-volatility precursors; n-alkanes were chosen as a model system. The experiments feature atmospherically relevant organic aerosol concentrations (C_OA). Under high-NO_x conditions SOA yields increased with increasing carbon number (lower volatility) for n-decane, n-dodecane, n-pentadecane, and n-heptadecane, reaching a yield of 0.51 for heptadecane at a C_OA of 15.4 μg m⁻³. As with other photo-oxidation systems, aerosol yield increased with UV intensity. Due to the log−linear relationship between n-alkane carbon number and vapor pressure as well as a relatively consistent product distribution it was possible to develop an empirical parametrization for SOA yields for n-alkanes between C₁₂ and C₁₇. This parametrization was implemented using the volatility basis set framework and is designed for use in chemical transport models. For C_OA < 2 μg m⁻³, the SOA mass spectrum, as measured with an aerosol mass spectrometer, had a large contribution from m/z 44, indicative of highly oxygenated products. At higher C_OA, the mass spectrum was dominated by m/z 30, indicative of organic nitrates. The data support the conclusion that lower volatility organic vapors are important SOA precursors.

The heterogeneous reactions of methacrolein (MAC) and methyl vinyl ketone (MVK) on α-Al₂O₃ surfaces have been studied in a flow reactor using transmission-Fourier Transform Infrared (T-FTIR) spectroscopy to monitor the reaction progress. Unlike SiO₂ particles where MAC and MVK are weakly physisorbed, the results in this work demonstrate that on α-Al₂O₃ particles MAC and MVK are irreversibly adsorbed and can rapidly react on the surface to form various products such as aldehydes, organic acids, hydrogen peroxide, and even higher molecular weight compounds. The initial uptake rates and initial uptake coefficients for MAC and MVK on α-Al₂O₃ under dry conditions were determined to explore the reactivity of the particles. Furthermore, the effect of water vapor on the heterogeneous reactions was also investigated as a function of relative humidity. Both the heterogeneous uptake and transformation of MAC and MVK on α-Al₂O₃ were largely suppressed under humid conditions due to the depletion of surface active sites by water molecules. On the basis of experimental results, atmospheric implications of heterogeneous reactions of MAC and MVK were discussed. Our work suggests that heterogeneous reactions on α-Al₂O₃ can be important sinks for MAC and MVK as well as possible contributors to atmospheric organic aerosol.

In this study, the degradation of diclofop-methyl (DM) and its main metabolite, diclofop (DC), in two soils under aerobic and anaerobic conditions were investigated using enantioselective HPLC. Under aerobic or anaerobic conditions, rapid hydrolysis to the corresponding acid diclofop (DC) was observed. The results from this study revealed that the degradation of DM in the two soils is not enantioselective, and the calculated half-lives (t_1/2) for the two soils were both less than 1 day. However, the degradation of DC in the two soils is enantioselective both under aerobic and anaerobic conditions, and the S-(-)-DC was preferentially degraded, resulting in relative enrichment of the R-(+)-form. The calculated t_1/2 values of the enantiomers of DC ranged between 8.7 and 43.3 days for aerobic incubation experiments and between 14.7 and 77.0 days for anaerobic incubation experiments, respectively. The enantiopure S-(-)- and R-(+)-DC were incubated under aerobic conditions, and it revealed significant enantiomerization with inversion of the S-(-)-enantiomer into R-(+)-enantiomer, and vice versa, and the S-(-)-DC showed a significantly higher inversion tendency than the R-(+)-DC.

This study develops a general quantification framework for consistent intermodel and intercatchment comparison of the nutrient and pollutant mass loading from multiple sources in a catchment area to downstream surface and coastal waters. The framework accounts for the wide spectrum of different transport pathways and travel times through the subsurface (soil, groundwater, sediment) and the linked surface (streams, lakes, wetlands) water systems of a catchment. The account is based on key flow partitioning and mass delivery fractions, which can be quantified differently by different flow and transport and reaction models. The framework application is exemplified for two Swedish catchment cases with regard to the transport of phosphorus and of a generic attenuating solute. The results show essential differences in model quantifications of transport pathways and temporal spreading, with important implications for our understanding of cause and effect in the catchment-scale nutrient and pollutant loading to downstream waters.

Models simulating the performance of UV reactors enhance our understanding of the fundamental principles governing the operation of these units. When modeling the performance of UV reactors, governing equations for all related phenomena are derived and solved. This research presents a step-by-step methodology to setup and solve the governing equations determining the performance of UV reactors and to evaluate the results. A computational fluid dynamic (CFD) model was developed in order to simulate UV photoreactors in the Eulerian framework for chemical removal using a UV-based hydroxyl radical initiated oxidation process. Verifying the results of the integrated CFD model, a novel method was developed using a modified planar laser-induced fluorescence technique for measuring tracer concentration profiles inside the UV reactor. In addition, the components of the CFD model—hydrodynamics and radiation—were evaluated using experimental profile throughout the entire reactor. This verified procedure can be applied to the simulation and optimization of UV photoreactors with various geometries and operating conditions.

Reactive transport simulations are a common approach for the quantitative assessment of contaminant biodegradation in the subsurface. To use knowledge on microbial kinetics for the simulation of in situ biodegradation, the mass transfer processes controlling the bioavailability of the contaminants need to be described appropriately. A common approach to account for this problem is using a linear exchange model controlling the link between bulk and bioavailable concentration. Assuming that the subsequent degradation is controlled by the bioavailable concentration, only, these two steps can be combined to an analytical expression for the overall reaction rate know as the Best-Equation. In our work, we evaluate this approach for its ability to describe biodegradation kinetics limited by pore-scale mass transfer. Results from explicit numerical and analytical simulations of mass transport and reactive consumption at the pore scale are used to test the accuracy of results obtained using the Best-Equation. Our analysis shows that strictly spoken the Best-Equation is not valid. However, a good approximation can be achieved with errors of less than 6% in cases of moderate bioavailability and much lower errors in cases of either low or high bioavailability. These results support the description of mass transfer processes used in many reactive transport models. Furthermore, we present a method to obtain an accurate estimate of the unknown rate parameter controlling the diffusive mass transfer processes at the pore scale.

Elevated in-stream temperature has led to a surge in the occurrence of parasitic intrusion proliferative kidney disease and has resulted in fish kills throughout Switzerland’s waterways. Data from distributed temperature sensing (DTS) in-stream measurements for three cloud-free days in August 2007 over a 1260 m stretch of the Boiron de Morges River in southwest Switzerland were used to calibrate and validate a physically based one-dimensional stream temperature model. Stream temperature response to three distinct riparian conditions were then modeled: open, in-stream reeds, and forest cover. Simulation predicted a mean peak stream temperature increase of 0.7 °C if current vegetation was removed, an increase of 0.1 °C if dense reeds covered the entire stream reach, and a decrease of 1.2 °C if a mature riparian forest covered the entire reach. Understanding that full vegetation canopy cover is the optimal riparian management option for limiting stream temperature, in-stream reeds, which require no riparian set-aside and grow very quickly, appear to provide substantial thermal control, potentially useful for land-use management.

The factors affecting patterns of benthic [seabed] biology and chemistry around 50 Scottish fish farms were investigated using linear mixed-effects models that account for inherent correlations between observations from the same farm. The abundance of benthic macrofauna and sediment concentrations of organic carbon were both influenced by a significant, albeit weak, interaction between farm size, defined as the maximum weight of fish permitted on site at any one time, and current speed. Above a farm size threshold of between 800 and 1000 t, the magnitude of effects at farms located in areas of elevated current speeds were greater than at equivalent farms located in more quiescent waters. Sediment concentrations of total organic matter were influenced by an interaction between distance and depth, indicating that wind-driven resuspension events may help reduce the accumulation of organic waste at farms located in shallow waters. The analyses presented here demonstrate that the production and subsequent fate of organic waste at fish farms is more complex than is often assumed; in isolation, current speed, water depth, and farm size are not necessarily good predictors of benthic impact.

In this paper, we address the manner in which the continuum-scale diffusive properties of smectite-rich porous media arise from their molecular- and pore-scale features. Our starting point is a successful model of the continuum-scale apparent diffusion coefficient for water tracers and cations, which decomposes it as a sum of pore-scale terms describing diffusion in macropore and interlayer “compartments.” We then apply molecular dynamics (MD) simulations to determine molecular-scale diffusion coefficients D_interlayer of water tracers and representative cations (Na⁺, Cs⁺, Sr²⁺) in Na-smectite interlayers. We find that a remarkably simple expression relates D_interlayer to the pore-scale parameter δ_nanopore ≤ 1, a constrictivity factor that accounts for the lower mobility in interlayers as compared to macropores: δ_nanopore = D_interlayer/D₀, where D₀ is the diffusion coefficient in bulk liquid water. Using this scaling expression, we can accurately predict the apparent diffusion coefficients of tracers H₂O, Na⁺, Sr²⁺, and Cs⁺ in compacted Na-smectite-rich materials.

Little is known about P species in agro-industrial byproducts from developing countries, which may be either pollutants or valuable soil amendments. The present study speciated P in dry (COD) and wet (COW) coffee, sisal (SIS), barley malt (BEB) and sugar cane processing (FIC) byproducts, and filter cakes of linseed (LIC) and niger seed (NIC) with sequential fractionation, solution ³¹P nuclear magnetic resonance (NMR) spectroscopy, and P K- and L_2,3-edge X-ray absorption near-edge structure (XANES) spectroscopy. The sequential P fractionation recovered 59% to almost 100% of total P (P_t), and more than 50% of P_t was extracted by H₂O and NaHCO₃ in five out of seven samples. Similarly, the NaOH + EDTA extraction for solution ³¹P NMR recovered 48−94% of P_t. The ³¹P NMR spectra revealed orthophosphate (6−81%), pyrophosphate (0−10%), and orthophosphate monoesters (6−94%). Orthophosphate predominated in COD, COW, SIS, and FIC, whereas BEB, LIC, and NIC were rich in orthophosphate monoesters. The concentrations of P_i and P_o determined in the sequential and NaOH + EDTA extractions and ³¹P NMR spectra were strongly and positively correlated (r = 0.88−1.00). Furthermore, the P K- and L_2,3-edge XANES confirmed the H₂SO₄−P_i detected in the sequential fractionation by unequivocal identification of Ca−P phases in a few samples. The results indicate that the combined use of all four analytical methods is crucial for comprehensive P speciation in environmental samples and the application of these byproducts to soil.

A high flow rate (300 L min⁻¹) multicapillary denuder was designed to collect trace atmospheric semivolatile organic compounds (SOCs). The denuder is coated with a reusable, polydimethylsiloxane stationary phase as a nonselective absorbent for SOCs. A solvent-free thermal desorption method was developed, including sample cleanup, that is selective for nonpolar SOCs, and has low consumables cost per sample. The entire sample is transferred into the gas chromatograph to minimize the sampling time required to collect detectable analyte mass. Trace concentrations (0.1−100 pg m⁻³) of polychlorinated biphenyls and hexachlorobenzene were measured in the atmosphere near Lake Superior in sample times of 3.2−6.2 h. Overall method precision was determined using field duplicates and compared to the conventional high-volume sampler method. Method precision (coefficient of variation) of 16% was found for the high-flow denuder compared to 21% for the high-volume method. The relative difference between the two methods was 25%, with the high-flow denuder method giving generally lower concentrations. The high-flow denuder is an alternative to high-volume or passive samplers when it is desirable to separate gaseous from particle-associated SOCs upstream of a filter. The method is advantageous for studies that require high temporal resolution.

Total organic halogen (TOX) is a collective parameter and a toxicity indicator for all the halogenated organic disinfection byproducts (DBPs) in a water sample. TOX can be measured with the adsorption−pyrolysis method based on Standard Method 5320B. This method involves concentration of organic halogens from water by adsorption onto activated carbon (AC) and removal of inorganic halides present on the AC by competitive displacement by nitrate ions. Since AC can also act as a reductant, this work studied whether the reduction of chlorinated DBPs by AC occurs during the TOX measurement, to what extent the reduction affects the measurement of TOX, what type of chlorinated DBPs can be reduced by AC, and whether the method for the TOX measurement can be improved. Initially, chlorinated Suwannee River fulvic acid samples were prepared and pretreated with precipitation/dialysis/ultrafiltration to minimize the chloride levels in the samples. It was found that the fractions of TOX in the precipitated, dialyzed, and ultrafiltered samples that were reduced by AC in 5 min were around 13%, 20% and 24%, respectively. The formation of some N-chloroamino compounds and their reactivity with AC were examined. The results indicate that organic chloramines are one type of DBPs in TOX that could be reduced by AC. It was demonstrated that slight oxidation of AC with ozone basically inhibited its reduction for TOX and meanwhile maintained its adsorption capacity for TOX.

Autistic disorder (AD) is a severe neurodevelopmental disorder typically identified in early childhood. Both genetic and environmental factors are implicated in its etiology. The number of individuals identified as having autism has increased dramatically in recent years, but whether some proportion of this increase is real is unknown. If real, susceptible populations may have exposure to controllable exogenous stressors. Using literature AD data from long-term (∼10-year) studies, we determined cumulative incidence of AD for each cohort within each study. These data for each study were examined for a changepoint year in which the AD cumulative incidence first increased. We used data sets from Denmark, California, Japan, and a worldwide composite of studies. In the Danish, California, and worldwide data sets, we found that an increase in AD cumulative incidence began about 1988−1989. The Japanese study (1988−1996) had AD cumulative incidence increasing continuously, and no changepoint year could be calculated. Although the debate about the nature of increasing autism continues, the potential for this increase to be real and involve exogenous environmental stressors exists. The timing of an increase in autism incidence may help in screening for potential candidate environmental stressors.

Bauxsol reagents (powder, slurry, or pellet forms) are powerful tools in environmental remediation and water and sewage treatment. However, when used in circum-neutral water treatments, cement-bound Bauxsol pellets produce a sustained pH and alkalinity spike due to the presence of unreacted CaO in the cement binder. This study developed a pellet treatment system to minimize the alkalinity/pH spike. The recipe for pelletization consisted of Bauxsol powder, ordinary Portland cement (OPC), hydrophilic fumed silica, aluminum powder, a viscosity modifier, and water. Several batches (including different ratios and sizes) were run using modified makeup waters (H₂O + CO₂ or NaHCO₃) or curing brines (CO₂, NaHCO₃, or Mg/CaCl₂). Alkalinity, pH stability, and slake durability tests were performed on pellets before and/or after curing. The best result for reducing the alkalinity/pH spike was obtained from a MgCl₂, CaCl₂ bath treatment using a Bauxsol:cement ratio of 2.8:1 (pH 8.28; alkalinity 75.1 mg/L) for a 100 g batch or 2.45:1 (pH 8.05; alkalinity 35.4 mg/L) for a 1 kg batch. Although brine curing does provide a control on pH/alkalinity release, the pellets may still contain unreacted CaO. Therefore, a freshwater rinse of pellets before treating circum-neutral waters is recommended as is the continued investigation of alternative pellet binders.

Effective water management is critical for social welfare and ecosystem health. Nevertheless, information necessary to meaningfully assess sustainable water use is incomplete. In particular, little information is available on supply chain or indirect water use for the production of goods and services in the United States. We estimate a vector of water withdrawals for all 428 sectors in the 2002 U.S. economic input−output table. The vector was applied using economic input−output life cycle assessment (EIO−LCA) methods to estimate direct and indirect water withdrawals for each sector’s production, both in terms of total withdrawals and per dollar of output. Agriculture and power generation account for an overwhelming majority of direct water withdrawals (90%). A majority of water use (60%) is indirect (“embodied” or “virtual” water) with 96% of the sectors using more water indirectly in their supply chains than directly. The food and beverage industry accounts for 30% of indirect withdrawals. These results can be useful for environmental life cycle assessment of U.S. production and other studies, especially to avoid truncation errors due to boundary setting associated with process based life cycle impact assessments. However, we conclude that better information on water use would be helpful for effective water management.

We present a model that integrates the economic input-output approach of life cycle assessment with environmental fate, exposure, and risk assessment to estimate the spatial distribution of air toxic health risks due to sector-specific economic activity in the U.S. The model is used to relate the economic activity and exposure potential (population density and meteorology) associated with point source emissions of the heavy metal and carcinogen, hexavalent chromium, or Cr(VI), on a county basis. Total direct annual airborne emissions of Cr(VI) in the U.S. were 44 tonnes in 2002, with 97% from facilities in four major sectors: power generation, wood, plastics, and chemicals, metals, and scientific services. These include 6 tonnes of Cr(VI) emitted in the supply chains of these sectors. A highly variable national distribution of lifetime cancer risk is predicted, with a population-weighted mean of 2.7 × 10⁻⁷, but with hot-spot counties with lifetime risks as high as 6 × 10⁻⁶. Furthermore, high exposures and risks tend to occur in more highly populated counties. In particular, the population of Los Angeles County is exposed to the highest level of risk in the country and almost three-quarters of the total predicted cancer incidence due to inhalation of airborne Cr(VI) emissions. This finding can be attributed largely to the use of Cr(VI) as a corrosion inhibitor by the scientific services sector facilities in the county, the use of shorter facility stacks, and their siting within a highly populated area. These results indicate that linking economic activity, emission estimates, and fate and transport models for air toxics can inform both life cycle impact and comparative health risk assessments, allowing us to better target emission reductions to minimize hot-spots of risk.

N,N-Diethylethanolamine (DEEA) is a very promising absorbent for CO₂ removal from gaseous streams, as it can be prepared from renewable resources. Aqueous mixtures of DEEA and piperazine (PZ) are attractive for the enhancement of CO₂ capture, due to the high CO₂ loading capacity of DEEA and high reactivity of PZ. In the present work, for the first time, the equilibrium and kinetic characteristics of the CO₂ reaction with such mixtures were considered. Kinetic data were obtained experimentally, by using a stirred cell reactor. These data were interpreted using a homogeneous activation mechanism, by which the investigated reaction was considered as a reaction between CO₂ and DEEA in parallel with the reaction of CO₂ with PZ. It is found that, in the studied range of temperatures, 298−308 K, and overall amine concentrations, 2.1−2.5 kmol/m³, this reaction system belongs to the fast pseudo-first-order reaction regime systems. The second-order rate constant for the CO₂ reaction with PZ was determined from the absorption rate measurements in the activated DEEA solutions, and its value at 303 K was found to be 24,450 m³/(kmol s).

The Southern Appalachian forest region of the U.S.—a region responsible for 23% of U.S. coal production—has 24 billion metric tons of high quality coal remaining of which mountaintop coal mining (MCM) will be the primary extraction method. Here we consider greenhouse gas emissions associated with MCM terrestrial disturbance in the life-cycle of coal energy production. We estimate disturbed forest carbon, including terrestrial soil and nonsoil carbon using published U.S. Environmental Protection Agency data of the forest floor removed and U.S. Department of Agriculture−Forest Service inventory data. We estimate the amount of previously buried geogenic organic carbon brought to the soil surface during MCM using published measurements of total organic carbon and carbon isotope data for reclaimed soils, soil organic matter and coal fragments. Contrary to conventional wisdom, the life-cycle emissions of coal production for MCM methods were found to be quite significant when considering the potential terrestrial source. Including terrestrial disturbance in coal life-cycle assessment indicates that indirect emissions are at least 7 and 70% of power plant emissions for conventional and CO₂ capture and sequestration power plants, respectively. To further constrain these estimates, we suggest that the fate of soil carbon and geogenic carbon at MCM sites be explored more widely.

A time trend study focusing on ski waxing technicians’ exposure to perfluorinated chemicals (PFCs) from fluorinated wax fumes was performed in 2007/2008. Levels of eight perfluorocarboxylates and three perfluorosulfonates were analyzed in monthly blood samples from eight technicians. Samples were collected before the ski season, i.e., preseason, then at four FIS World Cup competitions in cross country skiing, and finally during an unexposed 5-month postseason period. The perfluorinated carboxylates perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) bioaccumulate, and continued exposure may contribute to elevated levels in ski technicians compared to the general population. The wax technicians’ median blood level of PFOA is 112 ng/mL compared to 2.5 ng/mL in the general Swedish population. A significant correlation was found between number of working years and levels of perfluorocarboxylates. The PFOA levels in three technicians with “low” initial levels of PFOA (<10.0 ng/mL in preseason blood) increased by 254, 134, and 120%, whereas five technicians with “high” initial levels (>100 ng/mL in preseason sample) were at steady state. PFHxA is suggested to have a short half-life in humans relative the other perfluorocarboxylates. The levels of perfluorosulfonates were unaffected by the wax exposure.

This is the first study to implement a genomic approach to ascertain both transcriptional and functional end points of chronic Cu toxicity in fish associated with experimentally manipulated water chemistries. Over 21 d, zebrafish acclimated to softwater (Na⁺ = 0.06 mM, Ca²⁺ = 0.08 mM, Mg²⁺ = 0.03 mM) were exposed to the following: soft-water (Ctrl); 12 μg L⁻¹ Cu (Cu); 3.3 mM Na⁺ (Na); 3.3 mM Na⁺ + 12 μg L⁻¹ Cu (Na + Cu); 3.3 mM Ca²⁺ (Ca); or 3.3 mM Ca²⁺ + 12 μg L⁻¹ Cu (Ca + Cu). Although effective at reducing Cu load in all tissues, Na⁺ in the presence of Cu did not decrease the degree of oxidative damage, particularly in the gill and gut. In contrast, Ca + Cu treatment decreased Cu accumulation in gill, but not liver or gut, with no reduction in oxidative damage. Transcriptional analysis of candidate genes (atp7a, ctr1, ECaC, esr1) showed principally a down regulation of transcripts with the Cu only treatment, while Ca + Cu treatment restored some of the genes to control levels. Conversely, the Na + Cu treatment had a strong, opposing affect when compared to that of Cu alone. Zebrafish Affymetrix GeneChips revealed significantly clustered patterns of expression. Changes in expression induced by Cu appeared to be opposite to the majority of the other treatments. Our data on the preventative or enhancing effects of Na⁺ and Ca²⁺ both alone and in the presence of Cu, may, in the future, facilitate the incorporation of gene expression end points into a biotic ligand model predicting chronic Cu toxicity in this tropical model species of genomic importance.

Here we describe results from a proteomic study of protein−nanoparticle interactions to further the understanding of the ecotoxicological impact of silver nanoparticles (AgNPs) in the environment. We identified a number of proteins from Escherichia coli that bind specifically to bare or carbonate-coated AgNPs. Of these proteins, tryptophanase (TNase) was observed to have an especially high affinity for both surface modifications despite its low abundance in E. coli. Purified TNase loses enzymatic activity upon associating with AgNPs, suggesting that the active site may be in the vicinity of the binding site(s). TNase fragments with high affinities for both types of AgNPs were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Differences in peptide abundance/presence in mass spectra for the two types of AgNPs suggest preferential binding of some protein fragments based on surface coating. One high-binding protein fragment contained a residue (Arg103) that is part of the active site. Ag adducts were identified for some fragments and found to be characteristic of strong binding to AgNPs rather than association of the fragments with ionic silver. These results suggest a probable mechanism for adhesion of proteins to the most commonly used commercial nanoparticles and highlight the potential effect of nanoparticle surface coating on bioavailability.

Many important aspects of nanosilver behavior are influenced by the ionic activity associated with the particle suspension, including antibacterial potency, eukaryotic toxicity, environmental release, and particle persistence. The present study synthesizes pure, ion-free, citrate-stabilized nanosilver (nAg) colloids as model systems, and measures their time-dependent release of dissolved silver using centrifugal ultrafiltration and atomic absorption spectroscopy. Ion release is shown to be a cooperative oxidation process requiring both dissolved dioxygen and protons. It produces peroxide intermediates, and proceeds to complete reactive dissolution under some conditions. Ion release rates increase with temperature in the range 0−37 °C, and decrease with increasing pH or addition of humic or fulvic acids. Sea salts have only a minor effect on dissolved silver release. Silver nanoparticle surfaces can adsorb Ag⁺, so even simple colloids contain three forms of silver: Ag⁰ solids, free Ag⁺ or its complexes, and surface-adsorbed Ag⁺. Both thermodynamic analysis and kinetic measurements indicate that Ag⁰ nanoparticles will not be persistent in realistic environmental compartments containing dissolved oxygen. An empirical kinetic law is proposed that reproduces the observed effects of dissolution time, pH, humic/fulvic acid content, and temperature observed here in the low range of nanosilver concentration most relevant for the environment.

Diclofenac, a nonsteroidal anti-inflammatory drug, is widely detected in surface waters and can potentially cause deleterious effects in fish. Here, we investigated the biological effects of 21-day exposure to waterborne diclofenac at environmentally relevant concentrations (0, 0.5, 1, 5, and 25 μg/L) in rainbow trout. Accumulation of diclofenac in the bile was measured and responses in selected tissues were assessed via changes in the expression of selected genes (cytochrome P450 (cyp) 1a1, cyclooxygenase (cox) 1 and 2, and p53) involved in metabolism of xenobiotics, prostaglandin synthesis, and cell cycle control, respectively, together with histopathological alterations in these tissues. Diclofenac accumulated in the bile by a factor of between 509 ± 27 and 657 ± 25 and various metabolites were putatively identified as hydroxydiclofenac, diclofenac methyl ester, and the potentially reactive metabolite hydroxydiclofenac glucuronide. Expression levels of both cox1 and cox2 in liver, gills, and kidney were significantly reduced by diclofenac exposure from only 1 μg/L. Expression of cyp1a1 was induced in the liver and the gills but inhibited in the kidney of exposed fish. Diclofenac exposure induced tubular necrosis in the kidney and hyperplasia and fusion of the villi in the intestine from 1 μg/L. This study demonstrates that subchronic exposure to environmental concentrations of diclofenac can interfere with the biochemical functions of fish and lead to tissue damage, highlighting further the concern about this pharmaceutical in the aquatic environment.

Large-scale production of renewable synthetic natural gas from biomass (bioSNG) in Canada was assessed for its ability to mitigate energy security and climate change risks. The land area within 100 km of Canada’s network of natural gas pipelines was estimated to be capable of producing 67−210 Mt of dry lignocellulosic biomass per year with minimal adverse impacts on food and fiber production. Biomass gasification and subsequent methanation and upgrading were estimated to yield 16 000−61 000 Mm³ of pipeline-quality gas (equivalent to 16−63% of Canada’s current gas use). Life-cycle greenhouse gas emissions of bioSNG-based electricity were calculated to be only 8.2−10% of the emissions from coal-fired power. Although predicted production costs ($17−21 GJ⁻¹) were much higher than current energy prices, a value for low-carbon energy would narrow the price differential. A bioSNG sector could infuse Canada’s rural economy with $41−130 billion of investments and create 410 000−1 300 000 jobs while developing a nation-wide low-carbon energy system.

Cumulative energy demand has been used as a methodology to assess life cycle environmental impacts of commodity production since the early seventies, but has also been criticized because it focuses on energy only. During the past 30 years there has been much research into the development of more complex single-score life cycle impact assessment methodologies. However, a comprehensive analysis of potential similarities and differences between these methodologies and cumulative energy demand has not been carried out so far. Here we compare the cumulative energy demand of 498 commodities with the results of six frequently applied environmental life cycle impact assessment methodologies. Commodity groups included are metals, glass, paper and cardboard, organic and inorganic chemicals, agricultural products, construction materials, and plastics. We show that all impact assessment methods investigated often provide converging results, in spite of the different philosophies behind these methodologies. Fossil energy use is identified by all methodologies as the most important driver of environmental burden of the majority of the commodities included, with the main exception of agricultural products. We conclude that a wide range of life cycle environmental assessment methodologies point into the same environmental direction for the production of many commodities.

This study presents the first mechanistic model describing broth temperature in column photobioreactors as a function of static (location, reactor geometry) and dynamic (light irradiance, air temperature, wind velocity) parameters. Based on a heat balance on the liquid phase the model predicted temperature in a pneumatically agitated column photobioreactor (1 m² illuminated area, 0.19 m internal diameter, 50 L gas-free cultivation broth) operated outdoor in Singapore to an accuracy of 2.4 °C at the 95% confidence interval over the entire data set used (104 measurements from 7 different batches). Solar radiation (0 to 200 W) and air convection (−30 to 50 W) were the main contributors to broth temperature change. The model predicted broth temperature above 40 °C will be reached during summer months in the same photobioreactor operated in California, a value well over the maximum temperature tolerated by most commercial algae species. Accordingly, 18 000 and 5500 GJ year⁻¹ ha⁻¹ of heat energy must be removed to maintain broth temperature at or below 25 and 35 °C, respectively, assuming a reactor density of one reactor per square meter. Clearly, the significant issue of temperature control must be addressed when evaluating the technical feasibility, costs, and sustainability of large-scale algae production.

Many Jatropha curcas Linnaeus (JCL) plantations have been established in tropical and subtropical regions worldwide. To assess the potential of JCL for biofuel production, the potential areas for JCL plantations, and the yields of JCL must be estimated as accurately as possible. Here, we present a system approach to estimate JCL yields, classify yield levels, and estimate productivity of future JCL plantations. We used a process-based net primary productivity (NPP) model to estimate potential JCL yields. The model estimated that the potential yield of JCL dry seed will vary from 0 to 7.62 ton ha⁻¹ y⁻¹, in contrast to estimates of 1.50−7.80 ton ha⁻¹ y⁻¹ from previous assessments. We formulated a zoning scheme that takes into account land cover status and potential yield levels. This scheme was used to evaluate the potential area and production of future plantations at the global, regional, and national levels. The estimated potential area of JCL plantations is 59−1486 million hectares worldwide, and the potential production is 56−3613 million ton dry seed y⁻¹. This study provides scientific information on global patterns of potential plantation areas and yields, which can be used to support bioenergy policy makers to plan commercial-scale JCL plantations.