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Abstract: The study develops a bio-economic crop management model that internalizes the environmental cost of nitrate pollution, accounts for stochastic weather, and includes an option for split fertilization. The integrated model is designed to indicate whether a producer can benefit from applying fertilizer several times during the growing season, in response to crop needs, rather than a single time, at sowing. The model is parameterized for the cultivation of spring malting barley (Hordeum vulgare L.) in Southern Finland. The costs of negative externalities from nitrogen leaching are internalized in the landowner’s decision problem through a pollution tax. The results indicate that without a pollution tax a single application of fertilizer gauged to meet the needs of the entire season is optimal. With a tax, the benefits of split application – applying varying amounts of fertilizer at selected stages of the growing season – increase significantly. In comparison to a single application of fertilizer at sowing, split fertilization improves yields, increases the total amount of fertilizer used, and reduces nitrogen leaching. [Copyright &y& Elsevier]

Sulphur ( S) and nitrogen ( N) deposition are important drivers of the terrestrial carbon ( C) and N cycling. We analyzed changes in C and N pools in soil and tree biomass at a highly acidified spruce site in the Czech Republic during a 15 year period. Total S deposition decreased from 5 to 1.1 g m−2 yr−1 between 1995 and 2009, whereas bulk N deposition did not change. Over the same period, C and N pools in the Oa horizon declined by 116 g C and 4.2 g N m−2 yr−1, a total decrease of 47% and 42%, respectively. This loss of C and N probably originated from organic matter ( OM) that had accumulated during the period of high acid deposition when litter decomposition was suppressed. The loss of OM from the Oa horizon coincided with a substantial leaching (1.3 g N m−2 yr−1 at 90 cm) in the 1990s to almost no leaching (<0.02 g N m−2 yr−1) since 2006. Forest floor net N mineralization also decreased. This had consequences for spruce needle N concentration (from 17.1 to 11.4 mg kg−1 in current needles), an increase in litterfall C/N ratio (from 51 to 63), and a significant increase in the Oi + Oe horizon C/N ratio (from 23.4 to 27.3) between 1994 and 2009/2010. Higher forest growth and lower canopy defoliation was observed in the 2000s compared to the 1990s. Our results demonstrate that reducing S deposition has had a profound impact on forest organic matter cycling, leading to a reversal of historic ecosystem N enrichment, cessation of nitrate leaching, and a major loss of accumulated organic soil C and N stocks. These results have major implications for our understanding of the controls on both N saturation and C sequestration in forests, and other ecosystems, subjected to current or historic S deposition. [ABSTRACT FROM AUTHOR]

Leaching behavior of Sr and Cs in the vadose zone of Hanford site (Washington) was studied with laboratory-weathered sediments mimicking realistic conditions beneath the leaking radioactive waste storage tanks. Unsaturated column leaching experiments were conducted using background Hanford pore water focused on first 200 pore volumes. The weathered sediments were prepared by 6 months reaction with a synthetic Hanford tank waste leachate containing Sr and Cs (10-5 and 10-3 molal representative of LO- and HI-sediment, respectively) as surrogates for 90Sr and 137Cs. The mineral composition of the weathered sediments showed that zeolite (chabazite-type) and feldspathoid (sodalite-type) were the major byproducts but different contents depending on the weathering conditions. Reactive transport modeling indicated that Cs leaching was controlled by ion-exchange, while Sr release was affected primarily by dissolution of the secondary minerals. The later release of K, Al, and Si from the HI-column indicated the additional dissolution of a more crystalline mineral (cancrinite-type). A two-site ion-exchange model successfully simulated the Cs release from the LO-column. However, a three-site ion-exchange model was needed for the HI-column. The study implied that the weathering conditions greatly impact the speciation of the secondary minerals and leaching behavior of sequestrated Sr and Cs. [ABSTRACT FROM AUTHOR]

Re-mining of existing dumping sites for the extraction of coal residues (around 10% wt.) with subsequent reuse of a secondary waste in engineering constructions or its re-disposal in the environmentally safe way is an attractive and economically viable way of coal protection as a valuable natural resource and of adequate reduction of dumped waste volume. These methods of bulk waste re-use may though cause also negative consequences, if not properly controlled. In this article, the adverse environmental impacts of technological processes of coal extraction are exemplified in a coal mining waste dump in the Upper Silesia coal basin (USCB) in Poland, where coal waste has been reprocessed since 1998. Both the disturbance of original waste layers in the dump and altered exposure of the processed rock material to the atmospheric conditions during residual coal extraction, and secondary wastes re-disposal/re-use appeared to result in significant increase of groundwater salinity. Therefore, adverse effects of waste re-use and efficient and cost-effective methods of attenuation of salt loads release from this material should be taken into account. [ABSTRACT FROM AUTHOR]

Abstract: Cropland derived nitrate leaching was a major reason for groundwater pollution. The objective of this study was to on-farm investigate the behavior of nitrate leaching affected by N fertilization rates, rainfall, and temperature in a rainfed winter wheat field in Taihu watershed. The experiment had five urea-N rates (0–360kgNha−1 in 90-kg increments), and nitrate-N in leachate was daily collected by wedge-shaped fiberglass wick lysimeters during four stages (seeding stage, SS; tillering stage, TS; booting stage, BS; harvesting stage, HS). Results showed that: (1) higher potential of leachate would be engendered when the rainfall intensity was over 5.9mmd−1; (2) variations of nitrate concentrations in leachate were well responsed to three split fertilizations, which increased with the increase of urea-N applied rates. A similar variation pattern of nitrate concentrations was observed in −0.3m and −0.6m soil leachate. Besides, the nitrate concentrations in leachate could be raised with the sharply increase of air temperature, especially in the SS and TS stages; (3) the fluxes of nitrate leaching were significantly affected by N rates (P <0.05) with the loss ratio varied from 4.0% to 8.5% for five treatments, and the fluxes in four wheat growing stages followed the order of TS>HS>BS>SS. The N application rate of 180kgNha−1 optimized wheat production, but N application over that rate greatly increased nitrate leaching potential. Therefore, options other than lowering the N application rate need to be considered to reduce environmental impacts while maintain winter wheat production. [Copyright &y& Elsevier]

In Ouro Preto/MG, pyrite was exploited at an old mine from 1930 through 1967. Considered as one of the best resources of pyrite in Brazil, this mine was exploited in order to supply sulfuric acid for explosives manufacturing, at the President Vargas Plant in Piquete/SP. The mine site is abandoned and has slope instability and acid leakage generation as the main environmental liabilities. Lately, the site has been used for illegal deposition of all sorts of urban waste. The Ouro Preto Administration, on its turn, has the intention of using part of the mine site for the disposal of solid residues of civil construction. This paper presents the results of kinetic tests carried out, in leaching columns, to assess the acid mine drainage potential in samples collected from the mine site and to evaluate the possibility of controlling and minimizing acid generation by using solid residues as a covering system. Laboratory results show that cover with solid residues of civil construction was effective in the reducing the acidity, concentration of metals and sulfate. [ABSTRACT FROM AUTHOR]

Abstract: As much as 60% of the nitrate in water in England is thought to derive from agriculture. Legislation aims to improve water quality by limiting nitrate concentration in surface and groundwaters to 50mgl−1. The UK Government responded to the requirements of the EC Nitrate Directive by delineating Nitrate Vulnerable Zones (NVZs) to cover 55% of England in 2002 and increased it to 70% in 2009. In this study we assessed the cost-effectiveness of measures for implementation in livestock systems to mitigate nitrate leaching in the UK. These estimates were prepared for a range of hypothetical farms representative of typical dairy, beef and sheep farms at different locations in England and Wales and for a list of mitigation measures identified to reduce leaching. The NGAUGE and NFixCycle models were used to estimate leaching from these systems. The costs of implementation of the mitigation measures were also assessed in order to evaluate the cost-effectiveness of these measures. In general, the most effective measures to reduce leaching for all systems were the ones that involved a reduction in stocking rates and grazing time, followed by those involving improvements in fertiliser and crop management. Only in the case of the dairy system was effectiveness affected by location of the farm. The costs for implementation in the sheep system were relatively low compared with beef and dairy systems. Implementation of some of the measures with high cost-effectiveness would need to be incentivised financially or with legislation due to the high costs involved. [ABSTRACT FROM AUTHOR]

Abstract: In this contribution we give a first general overview of results of recent studies in Germany which focused on contaminant leaching from various materials and reactive solute transport in the unsaturated soil zone to identify the key factors for groundwater risk assessment. Based on these results we developed new and improved existing methods for groundwater risk assessment which are used to derive a new regulatory concept for the upcoming “Decree for the Requirements of the Use of Alternative Mineral Building Materials in Technical Constructions and for the Amendment of the Federal Soil Protection and Contaminated Sites Ordinance” of the German Federal Ministry of Environment. The new concept aims at a holistic and scientifically sound assessment of the use of mineral recycling materials (e.g., mineral waste, excavated soils, slag and ashes, recycling products, etc.) in technical constructions (e.g., road dams) and permanent applications (e.g., backfilling and landscaping) which is based on a mechanistic understanding of leaching and transport processes. Fundamental for risk assessment are leaching standards for the mineral recycling materials. For each application of mineral recycling materials specific maximum concentrations of a substance in the seepage water at the bottom of an application were calculated. Technical boundary conditions and policy conventions derived from the “German precautionary groundwater and soil protection policy” were accounted to prevent adverse environmental effects on the media soil and groundwater. This includes the concentration decline of highly soluble substances (e.g., chloride and sulphate), retardation or attenuation of solutes, accumulation of contaminants in sub-soils and the hydraulic properties of recycling materials used for specific applications. To decide whether the use of a mineral recycling material is possible in a specific application, the leaching qualities were evaluated based on column percolation tests with various samples and compared with application-specific maximum concentrations. In the upcoming federal decree this simplified concept is realized using detailed tables which classify the leaching quality of mineral recycling materials and demonstrate potential application. A quality assurance system will be mandatory which defines specific testing programs (material properties and limit concentrations to be tested, number and schedule of testing) for the different mineral recycling materials using standardized methods (column percolation test). [Copyright &y& Elsevier]

Abstract: In Sweden, leaching tests with deionized water (D.W.) are utilized in risk assessment of materials entering landfills, but implementation of these results to evaluate the risk of spreading of pollutants in the environment is difficult. One problem is that most leaching procedures only consider heavy metals release, whereas organic pollutants are left out. The aim of the present study was to assess the possible pollutant mitigation in four remediated soils, three with heavy metals and one with polycyclic aromatic hydrocarbons (PAH) contamination. The mitigation was evaluated by standardized batch and column leaching tests utilizing three different leaching solutions: D.W., a weak ionic solution (0.001M CaCl2) and an artificially made soil water (ASW). In general, batch leaching tests implied larger contaminant removal than column leaching test, possibly due to the more rough treatment of the soil particles, and guidelines would at times be exceeded by the batch leaching test but not by column leaching tests. Utilization of CaCl2 was found to release less heavy metal than D.W., whereas the metals mobilized by ASW were removed from solution by the filtration of soil leachates. Low molecular weight PAH was most efficiently mobilized by CaCl2, while D.W. worked better for high molecular weight PAH. Despite very low initial PAH-concentrations, tap- and groundwater criteria were exceeded by all leaching solutions. [ABSTRACT FROM AUTHOR]

Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH), at forests, grasslands, and croplands across Europe. Biogenic contributions to DIC were estimated by means of its δC signature. Leaching of biogenic DIC was 8.3±4.9 g m yr for forests, 24.1±7.2 g m yr for grasslands, and 14.6±4.8 g m yr for croplands. DOC leaching equalled 3.5±1.3 g m yr for forests, 5.3±2.0 g m yr for grasslands, and 4.1±1.3 g m yr for croplands. The average flux of total biogenic carbon across land use systems was 19.4±4.0 g C m yr. Production of DOC in topsoils was positively related to their C/N ratio and DOC retention in subsoils was inversely related to the ratio of organic carbon to iron plus aluminium (hydr)oxides. Partial pressures of CO in soil air and soil pH determined DIC concentrations and fluxes, but soil solutions were often supersaturated with DIC relative to soil air CO. Leaching losses of biogenic carbon (DOC plus biogenic DIC) from grasslands equalled 5-98% (median: 22%) of net ecosystem exchange (NEE) plus carbon inputs with fertilization minus carbon removal with harvest. Carbon leaching increased the net losses from cropland soils by 24-105% (median: 25%). For the majority of forest sites, leaching hardly affected actual net ecosystem carbon balances because of the small solubility of CO in acidic forest soil solutions and large NEE. Leaching of CH proved to be insignificant compared with other fluxes of carbon. Overall, our results show that leaching losses are particularly important for the carbon balance of agricultural systems. [ABSTRACT FROM AUTHOR]

The article discusses nitrogen (N) contamination of surficial aquifers. A brief historical perspective regarding the various ways N has been released into the environment since the end of World War Two (WWII) is presented, including an increased use of fertilizers, fixation by crops, and the mineralization of animal manure. An overview of groundwater's vulnerability for contamination from mobile N compounds, such as nitrate (NO3-), applications for the assessment of NO3- contamination in groundwater, and spatio-temporal patterns of NO3- in groundwater samples is presented.

Purpose: Hexachlorocyclohexane (HCH) isomers (α-, β- and γ- (Lindane)) were recently included as new persistent organic pollutants (POPs) in the Stockholm Convention, and therefore, the legacy of HCH and Lindane production became a contemporary topic of global relevance. This article wants to briefly summarise the outcomes of the Stockholm Convention process and make an estimation of the amount of HCH waste generated and dumped in the former Lindane/HCH-producing countries. Results: In a preliminary assessment, the countries and the respective amount of HCH residues stored and deposited from Lindane production are estimated. Between 4 and 7 million tonnes of wastes of toxic, persistent and bioaccumulative residues (largely consisting of alpha- (approx. 80%) and beta-HCH) are estimated to have been produced and discarded around the globe during 60 years of Lindane production. For approximately 1.9 million tonnes, information is available regarding deposition. Countries are: Austria, Brazil, China, Czech Republic, France, Germany, Hungary, India, Italy, Japan, Macedonia, Nigeria, Poland, Romania, Slovakia, South Africa, Spain, Switzerland, Turkey, The Netherlands, UK, USA, and former USSR. The paper highlights the environmental relevance of deposited HCH wastes and the related POPs' contaminated sites and provides suggestions for further steps to address the challenge of the legacy of HCH/Lindane production. Conclusion: It can be expected that most locations where HCH waste was discarded/stockpiled are not secured and that critical environmental impacts are resulting from leaching and volatilisation. As parties to the Stockholm Convention are legally required to take action to stop further POPs pollution, identification and evaluation of such sites are necessary. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) are advertised as environmentally friendly because they are energy efficient and mercury-free. This study aimed to determine if LEDs engender other forms of environmental and human health impacts, and to characterize variation across different LEDs based on color and intensity. The objectives are as follows: (i) to use standardized leachability tests to examine whether LEDs are to be categorized as hazardous waste under existing United States federal and California state regulations; and (ii) to use material life cycle impact and hazard assessment methods to evaluate resource depletion and toxicity potentials of LEDs based on their metallic constituents. According to federal standards, LEDs are not hazardous except for low-intensity red LEDs, which leached Pb at levels exceeding regulatory limits (186 mg/L; regulatory limit: 5). However, according to California regulations, excessive levels of copper (up to 3892 mg/kg; limit: 2500), Pb (up to 8103 mg/kg; limit: 1000), nickel (up to 4797 mg/kg; limit: 2000), or silver (up to 721 mg/kg; limit: 500) render all except low-intensity yellow LEDs hazardous. The environmental burden associated with resource depletion potentials derives primarily from gold and silver, whereas the burden from toxicity potentials is associated primarily with arsenic, copper, nickel, lead, iron, and silver. Establishing benchmark levels of these substances can help manufacturers implement design for environment through informed materials substitution, can motivate recyclers and waste management teams to recognize resource value and occupational hazards, and can inform policymakers who establish waste management policies for LEDs. [ABSTRACT FROM AUTHOR]

This paper assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. First, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribution, trends, and trend reversals in the groundwater nitrate concentration. Second, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Third, groundwater recharge CFC (chlorofluorocarbon) age determination allows linking of the first two data sets. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded in decreasing the N surplus by 40% since the mid 1980s, while at the same time maintaining crop yields and increasing the animal production of especially pigs. Trend analyses prove that the youngest (0-15 years old) oxic groundwater shows more pronounced significant downward nitrate trends (44%) than the oldest (25-50 years old) oxic groundwater (9%). This amounts to clear evidence of the effect of reduced nitrate leaching on groundwater nitrate concentrations in Denmark. [ABSTRACT FROM AUTHOR]

Variations in wastewater composition in the case of seepage through levees bounding treatment facilities as a function of the composition of dump rock and recirculation water of the concentrating mill. The character and degree of pollutant leaching is established as a function environmental pH. Measures for mitigating the adverse impact of the interaction between disintegrated tailing dumps and rock-forming overburden with the recirculation water of tailing dump on water resources of the area of production activity of the Kovdor Mining-and-Processing Integrated Works (MPIW) [ABSTRACT FROM AUTHOR]

Abstract: Three pilot scale lysimeters were adopted to evaluate the stability pattern and leaching potential of heavy metals from MSW landfills under the E-waste co-disposed condition. One lysimeter served as control and solely filled with MSW, whereas the other two lysimeters were provided with 10% and 25% of E-waste scraps (% by weight), respectively. The reactors were monitored over a period of 280days at ambient settings with continuous leachate recirculation. Stabilization pattern of carbon appears to be more than 50% in all the three lysimeters with irrespective of their operating conditions. Iron and zinc concentrations were high in leachate during bioreactor landfill operation and correlating with the TCLP leachability test results. In contrast, Pb concentration was around <0.6mg/L, but which showed maximum leaching potential under TCLP test conditions. But, no heavy metal accumulation was found with leachate recirculation practices in lysimeters. Mobility of the metal content from the E-waste was found to be amplified with the long term disposal or stabilization within landfills. The results showed that the TCLP test cannot be completely reliable tool for measuring long-term leachability of toxic substances under landfill condition; rather landfill lysimeter studies are necessary to get the real scenario. [ABSTRACT FROM AUTHOR]

Abstract: We investigated an environmentally friendly leaching process for the recovery of cobalt and lithium from the cathode active materials of spent lithium-ion batteries. The easily degradable organic acid DL-malic acid (C4H5O6) was used as a leaching reagent. The structural, morphology of the cathode materials before and after leaching were characterized by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The amount of Co and Li present in the leachate was determined by atomic absorption spectrophotometry (AAS). Conditions for achieving a recovery of more than 90 wt.% Co and nearly 100 wt.% Li were determined experimentally by varying the concentrations of leachant, time and temperature of the reaction as well as the initial solid-to-liquid ratio. We found that hydrogen peroxide in a DL-malic acid solution is an effective reducing agent because it enhances the leaching efficiency. Leaching with 1.5M DL-malic acid, 2.0 vol.% hydrogen peroxide and a S:L of 20gL−1 in a batch extractor results in a highly efficient recovery of the metals within 40min at 90°C. [ABSTRACT FROM AUTHOR]

Atrazine and phenanthrene (Phen) sorption by nonhydrolyzable carbon (NHC), black carbon (BC), humic acid (HA) and whole sediment and soil samples was examined. Atrazine sorption isotherms were nearly linear. The single-point organic carbon (OC)-normalized distribution coefficients (K OC) of atrazine for the isolated HA1, NHC1 and BC1 from sediment 1 (ST1) were 36, 550, and 1470 times greater than that of ST1, respectively, indicating the importance of sediment organic matter, particularly the condensed fractions (NHC and BC). Similar sorption capacity of atrazine and Phen by NHC but different isotherm nonlinearity indicated different sorption domains due to their different structure and hydrophobicity. The positive relationship between (O+N)/C ratios of NHC and atrazine log K OC at low concentration suggests H-bonding interactions. This study shows that sediment is probably a less effective sorbent for atrazine than Phen, implying that atrazine applied in sediments or soils may be likely to leach into groundwater. [Copyright &y& Elsevier]

Abstract: Environmental conditions can have major influences in shaping biophysical properties of leaf surfaces. In moist environments, high leaf water repellency (LWR) is expected because the presence of a water film on leaf surfaces can block stomatal pores, reduce the diffusion of CO2, promote pathogen incidence, colonization of epiphylls and leaching of leaf nutrients. However, LWR can also increase in dry environments as a consequence of higher epicuticular wax deposition induced by high temperatures, high radiation loads and vapor pressure deficits (VPD), which could also lead to a high leaf mass per area (LMA). The aim of this study was to determine how LWR varies among tropical trees with contrasting crown exposures and subjected to distinct vapor pressure deficits at different altitudes in the Atlantic Rain Forest. We hypothesized that (i) LWR will be higher in overstory species because they are more frequently exposed to higher radiation and higher vapor pressure deficit; (ii) In the Montane Forest, LWR will be higher for overstory species in comparison to those in Lowland Forest because radiation and VPD increase with altitude; (iii) Overstory species will also show higher LMA in response to exposure to drier conditions. We measured LWR by observing angles of droplets on adaxial and abaxial leaf surfaces in five species co-occurring at lowland and a montane forest. LWR was positively related to crown exposure and VPD at both sites but not to LMA. LWR was significantly higher in the Montane forest (mean angle 66.25°) than in the Lowland forest (mean angle 61.33°). We suggest that atmospheric conditions associated with contrasting crown exposures may exert important controls over leaf surface properties involved in the repellence or direct absorption of water. [ABSTRACT FROM AUTHOR]

In the evaluation of the risk of pesticide leaching to groundwater, the soil surface is usually assumed to be level, although important crops like potato are grown on ridges. A fraction of the water from rainfall and sprinkler irrigation may flow along the soil surface from the ridges to the furrows, thus bringing about an extra load of water and pesticide on the furrow soil. A survey of the literature reveals that surface-runoff from ridges to furrows is a well-known phenomenon but that hardly any data are available on the quantities of water and pesticide involved. On the basis of a field experiment with additional sprinkler irrigation, computer simulations were carried out with the Pesticide Emission Assessment at Regional and Local scales model for separate ridge and furrow systems in a humic sandy potato field. Breakthrough curves of bromide ion (as a tracer for water flow) and carbofuran (as example pesticide) were calculated for 1-m depth in the field. Bromide ion leached comparatively fast from the furrow system, while leaching from the ridge system was slower showing a maximum concentration of about half of that for the furrow system. Carbofuran breakthrough from the furrow system began about a month after application and increased steadily to substantial concentrations. Because the transport time of carbofuran in the ridge soil was much longer, no breakthrough occurred in the growing season. The maximum concentration of carbofuran leaching from the ridge-furrow field was computed to be a factor of six times as high as that computed for the corresponding level field. The study shows that the risk of leaching of pesticides via the furrow soil can be substantially higher than that via the corresponding level field soil. [ABSTRACT FROM AUTHOR]

Changes in emissions control at U.S. coal-fired power plants will shift metals content from the flue gas to the air pollution control (APC) residues. To determine the potential fate of metals that are captured through use of enhanced APC practices, the leaching behavior of 73 APC residues was characterized following the approach of the Leaching Environmental Assessment Framework. Materials were tested over pH conditions and liquid-solid ratios expected during management via land disposal or beneficial use. Leachate concentrations for most metals were highly variable over a range of coal rank, facility configurations, and APC residue types. Liquid-solid partitioning (equilibrium) as a function of pH showed significantly different leaching behavior for similar residue types and facility configurations. Within a facility, the leaching behavior of blended residues was shown to follow one of four characteristic patterns. Variability in metals leaching was greater than the variability in totals concentrations by several orders of magnitude, inferring that total content is not predictive of leaching behavior. The complex leaching behavior and lack of correlation to total contents indicates that release evaluation under likely field conditions is a better descriptor of environmental performance than totals content or linear partitioning approaches. [ABSTRACT FROM AUTHOR]

The article presents a study on the evaluation of the hydrological models in Bologna, Italy. The study intends to solve the health-related problems derived from the pollutants leaching. The study makes use of the cropping system model in the evaluation of leachates under the different environmental, social and management conditions.

Dissolved organic matter (DOM), produced through leaching from particulate organic matter (POM), is an essential component of the carbon cycle in streams. The present study investigated the instream DOM release from POM, varying in size and chemical quality. We produced large and medium sized fine particulate organic matter (L-FPOM, 250–500 μm; M-FPOM, 100–250 μm) of defined quality by feeding five types of coarse particulate organic matter (CPOM) to shredding amphipods ( Gammarus spp.). Microscopic observations showed that L-FPOM and M-FPOM mainly consisted of the fecal pellets of amphipods, and incompletely eaten plant fragments, respectively. DOM release experiments were conducted by exposing CPOM and M- and L-FPOM fractions in natural stream water over a two week period. For CPOM, the release of dissolved organic carbon (DOC) by leaching was highest during the first 6 h (3.64–23.9 mg C g C h) and decreased rapidly afterwards. For M- and L-FPOM, the DOC release remained low during the entire study period (range: 0.008–0.15 mg C g C h). Two-way ANOVA revealed that the DOC release rate significantly differed with POM source and size fraction, both at day 1 and after a week of exposure. Multiple regression analyses revealed a significant correlation of elemental contents and lignin content to DOC release rate after a week of exposure. Overall, the results indicated that DOC release rate of FPOM, on a carbon basis, is comparable to that of CPOM after leaching, while size and source of POM significantly affect DOC release rate. [ABSTRACT FROM AUTHOR]

Abstract: The chemical states of boron in coal fly ash, which may control its leaching into the environment, were investigated by focused-ion-beam time-of-flight secondary ion mass spectrometry (FIB-TOF-SIMS) and satellite-transition magic angle spinning nuclear magnetic resonance (STMAS NMR) spectroscopy. The distribution of boron on the surface and in the interior of micron-sized fly ash particles was directly observed by FIB-TOF-SIMS. Coordination numbers of boron and its bonding with different atoms from particles of bulk samples were investigated by STMAS NMR. Boron in coal fly ash with relatively poor leaching characteristics appears as trigonal BO3 and coexists with Ca and Fe at the outer layer of every particle and inside CaO–MgO particles. In contrast, boron in coal fly ash with better leaching characteristics appears as CaO- or MgO-trigonal BO3 and tetragonal BO4, and it is distributed only on the outer surface of each ash particle without showing any correlation with a particular element. [Copyright &y& Elsevier]

In vitro bioaccessibility (IVBA) studies were carried out on samples of mercury (Hg) mine-waste calcine (roasted Hg ore) by leaching with simulated human body fluids. The objective was to estimate potential human exposure to Hg due to inhalation of airborne calcine particulates and hand-to-mouth ingestion of Hg-bearing calcines. Mine waste calcines collected from Hg mines at Almadn, Spain, and Terlingua, Texas, contain Hg sulfide, elemental Hg, and soluble Hg compounds, which constitute primary ore or compounds formed during Hg retorting. Elevated leachate Hg concentrations were found during calcine leaching using a simulated gastric fluid (as much as 6200 μg of Hg leached/g sample). Elevated Hg concentrations were also found in calcine leachates using a simulated lung fluid (as much as 9200 μg of Hg leached/g), serum-based fluid (as much as 1600 μg of Hg leached/g), and water of pH 5 (as much as 880 μg of Hg leached/g). The leaching capacity of Hg is controlled by calcine mineralogy; thus, calcines containing soluble Hg compounds contain higher leachate Hg concentrations. Results indicate that ingestion or inhalation of Hg mine-waste calcine may lead to increased Hg concentrations in the human body, especially through the ingestion pathway. [ABSTRACT FROM AUTHOR]

In order to test the possibility for recycling use of aged refuse as sward soil, the study determined the responses of Lolium perenne L. (perennial ryegrass), Festuca arundinacea (tall fescue), and Poa annua (annual bluegrass) to its leaching. The growth of three seedlings was significantly inhibited after treatment, especially for longer treatment duration and higher concentration leaching; however, with the better growth and chlorophyll content for shorter time and lower concentration, tall fescue was more tolerant to the stress. Afterwards, several physiological responses of tall fescue were determined. For shorter treatment duration, antioxidant enzyme activities remained unchanged, and no obvious oxidative damage was observed. Prolonging exposure time, lipid peroxidation and protein oxidation occurred after treatment of higher concentration leaching, accompanying by changes of antioxidant status. It implicates that it is possible for using aged refuse as sward soil, and the critical point focused on selecting tolerant grass and controlling exposure condition. [Copyright &y& Elsevier]

ABSTRACT: Geochemical analysis of soils using partial extractions, purported to detect only a fraction of elements mobilized during dispersion, represents a useful exploration tool. Interpretation of partial extraction data is, however, subject to uncertainty because the effects of changing soil or sediment properties on extraction are poorly defined. In particular, soil properties which are known to affect the retention of metal ions (e.g. clay content, organic carbon content, pH) may provide useful parameters against which to calculate adjusted total and partial assay values and thereby enhance anomaly contrast in geochemical exploration. Bulk cyanide leach (BCL), a commonly-used weak partial extraction technique, reduces the nugget effect for Au and can provide higher anomaly contrast than total elemental analyses. For a range of elements (Ag, Au, Cd, Co, Cu, Mo, Ni, Pd and Zn), we conducted BCL determinations, measured the same elements by NAA, XRF or aqua regia digest, and determined a range of soil chemical properties for traverses at 10 exploration prospects in Australia and Namibia. Raw total and BCL data were compared with (i) concentration : soil parameter ratios, and (ii) adjusted BCL values based on a simple model of trace element speciation in soils. Anomaly contrasts for raw and normalized or adjusted data were compared using an estimate of anomalism based on both quantitative and heuristic criteria. At prospects with soils containing detectable carbonate, normalization of total and BCL assays to carbonate content significantly improved multi-element anomaly contrast. Normalization to amorphous Fe or Mn oxide content, or total Al, K or Mg also significantly improved anomaly contrast at fewer prospects. Adjusting BCL values using a simple adsorption model also showed limited success in improving anomaly contrast, and represents a useful framework for interpreting weak partial extraction data. [ABSTRACT FROM AUTHOR]

Abstract: Char residues produced in the co-pyrolysis of different wastes (plastics, pine biomass and used tyres) were characterized using chemical and toxicity assays. One part of the solid chars was submitted to extraction with dichloromethane (DCM) in order to reduce the toxicity of the char residues by removing organic contaminants. The different volatility fractions present in the extracted char (Char A) and in the raw char (Char B) were determined by progressive weight loss combustion. A selected group of heavy metals (Cd, Pb, Zn, Cu, Hg and As) was determined in both chars. The chars were subjected to the leaching test and the resulting eluates were further characterized by determining a group of inorganic parameters (pH, conductivity, Cd, Pb, Zn, Cu, Hg and As contents) and the concentrations of several organic contaminants (volatile aromatic hydrocarbons and alkyl phenols). An ecotoxicological characterization was also performed by using the bio-indicator Vibrio fischeri. The chemical and ecotoxicological results were analyzed according to the Council Decision 2003/33/CE and the criteria on the evaluation methods of waste ecotoxicity (CEMWE). The results obtained in this work indicated that the extraction with DCM is an effective method for the removal of organic contaminants of high to medium volatility from pyrolysis solid residues, thus decreasing their toxicity potential. Zn can be leached from the chars even after the DCM extraction treatment and can contribute to the ecotoxicity of the eluates obtained from chars. Both chars (treated and non treated with DCM) were classified as hazardous and ecotoxic wastes. [Copyright &y& Elsevier]

The relationships developed between soil properties and phytotoxicity threshold values for copper require validation in a wide range of soils with different properties and climate characteristics before they can be applied for regulatory purposes in countries throughout the world. Seventeen soils, which are representative of the major soil types and properties in China, were spiked with Cu chloride. A subset of the Cu-spiked soils was leached with artificial rain water to compare toxicity with that in unleached soils. Barley root elongation tests were performed under controlled environmental conditions. The concentrations of added Cu causing a 50% inhibitory effect (EC50) ranged from 67 to 1,129 mg/kg in unleached soils and from 88 to 1,255 mg/kg in leached soil. Compared with the unleached toxicity thresholds, the leached EC10 (10% inhibition) and EC50 were higher by an average of 1.43- and 1.15-fold, respectively. Soil leaching significantly (p ≤ 0.05) decreased the toxicity of Cu in approximately 35% of the soils. In this study, no single soil property was found to explain over 35% of the variance in (log transformed) EC50. However, stepwise multiple regressions using soil pH, organic carbon (OC) content, and effective cation exchange capacity (eCEC) were found to explain over 80% of the variance in Cu toxicity across soils. The model developed for Chinese soils based on these factors was found to predict significantly (r2, 0.90) the phytotoxicity of Cu in European soils. These quantitative relationships between Cu toxicity and soil properties are helpful for developing soil-specific guidance on Cu toxicity thresholds. Environ. Toxicol. Chem. 2010;29:835–842. © 2009 SETAC [ABSTRACT FROM AUTHOR]

Abstract: There is increasing interest in the stabilization of heavy metals in road-derived sediments (RDS), to enable environmentally responsible reuse applications and circumvent the need for costly landfill disposal. To reduce the mobility of heavy metals (i.e. Cu, Pb and Zn) the effectiveness of amendments using phosphate, compost and fly ash addition were investigated using batch leaching experiments. In general, phosphate amendments of RDS were found to be ineffective at stabilizing heavy metals, despite being used successfully in soils. Phosphate amendment resulted in enhanced concentrations of dissolved organic carbon (DOC), which increased the solubilisation of heavy metals via complexation. Amendment with humified organic matter (compost) successfully stabilized Cu and Pb in high DOC leaching RDS with an optimum loading of 15–20% (w/w). Compost, however, was ineffective at stabilizing Zn. Increasing the pH by amending RDS/compost blends with 2.5–15% (w/w) coal fly ash resulted in the stabilization of Zn, Cu and Pb. However, above a pH of ∼7.5 and 8 enhanced leaching of organic matter resulted in an increase in leached Cu and Pb, respectively. Accordingly, the optimum level of fly ash amendment for the RDS/compost blends was estimated to be ca. 10%. Boosted regression trees analysis (BRT) of the data revealed that DOC accounted for 56% and 65% of the Cu and Pb leaching, respectively, whereas pH only accounted for ca. 18% of Cu and Pb leaching. RDS sample characteristics (i.e. metal concentrations, size fractionation and organic matter content) were more important at reconciling the leaching concentrations of copper Cu (27%) than Pb (16%). The most important parameter explaining Zn leaching was pH. Overall, the choice of a suitable stabilization agent/s depends on the composition of RDS with respect to the amount of organic matter present, and the sorption chemistry of the heavy metal of interest. [Copyright &y& Elsevier]

Abstract: The use of dispersants to treat oil spills in calm seas is discouraged because there is insufficient ‘mixing energy’ to cause immediate dispersion of the oil. However, dispersants might be applied while the seas are calm, in the expectation that they would work later when sea states increase. The present study examined the persistence of dispersants in treated oil slicks on calm water in a large outdoor wave tank. Test slicks, pre-mixed with dispersant, were allowed to stand on static and flowing water for up to six days, after which their dispersibility was tested by exposing them to breaking waves. Results showed that thicker slicks exposed to calm water for up to six days dispersed completely with the addition of breaking waves. Thinner slicks and slicks exposed to water movement became less dispersible within two days. The loss of dispersibility was caused by dispersant loss rather than by oil weathering. [Copyright &y& Elsevier]

Leaching of Cu and Zn from a composite of discarded antifouling paint residues ([Cu] = 288 mg g−1; [Zn] = 96 mg g−1) into natural sea water has been studied over a period of 75 h. Total Cu and Zn were released according to a pseudo first-order reaction, with rate constants on the order of 0.3 and 2.5 (mg L−1)−1 h−1, respectively, and final concentrations equivalent to the dissolution of about 8 and 2% of respective concentrations in the composite. Time-distributions of hydrophobic metals, determined by solid phase extraction-methanol elution, were more complex. Net release of hydrophobic Cu was greater in the absence of light than under a sequence of light–dark cycles; however, hydrophobic Zn release was not detected under the former conditions but contributed up to 50% of total aqueous Zn when light was present. These observations are interpreted in terms of the relative thermodynamic and photolytic stabilities of biocidal pyrithione complexes. [Copyright &y& Elsevier]

Concrete is usually the preferred material for construction of structures in contact with water during their service life. Early age exposure to water is beneficial for curing of concrete structures. However, the pollution of water from freshly cast concrete in contact with water has not been investigated in detail. A significant increase in the alkalinity has recently been observed in a stream in contact with freshly installed concrete culverts. High alkalinity has caused distress to fresh water fish in the stream. A preliminary laboratory study was commenced to explore the effect of leaching of alkali into water from freshly placed concrete. Freshly cast concrete specimens were exposed to fresh water, covering a range of conditions observed in the field such as volume of concrete/volume of water, age of exposure and cement content. Analysis of the results indicated that early age contact with fresh concrete can lead to an increase in the pH levels of water up to 11, similar to the levels of pH observed in pore water inside freshly cast concrete. It was noted that until an age of 4 days from casting of concrete, the age of exposure does not significantly affect the changes in the peak pH levels of water. Continuous monitoring of water in contact with concrete also indicated that the pH levels diminish with time, which is attributed to the possible reaction of calcium hydroxide with atmospheric carbon. The paper will present the experimental study, the results, analysis and outcomes as well as planning of a more comprehensive study to observe possible ways of reducing the leaching of alkali from freshly placed concrete. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study on Phragmites australis leaf litter decomposition was conducted in the estuarine environment, Ria de Aveiro, Western Portugal, using the leaf-bag technique, with fine- (1mm) and coarse-mesh (5mm) bags. The leaf bags were placed in the field sites at day 0, covering a complete salinity gradient, and replicates were collected over time, at days 3 (leaching), 7, 15, 30 and 60. The biomass loss through the leaching phase, about 20% of the initial leaf mass, was independent of both the salinity and the bag mesh size. The biomass decay pattern along the salinity gradient varied through time and presented strong similarities between the two mesh sizes, with the remaining biomass always lower in the 5mm mesh-size bags. At days 7 and 15, the lowest remaining biomass was observed at the head of the estuary, the preferential distribution area of P. australis. At day 30, the remaining biomass was higher in the marine area and diminished under a direct relationship with salinity, reaching the lowest value in the freshwater environment, with values ranging from 66% to 44% of the initial weight in 5mm bags, and from 79% to 51% in 1mm bags. The largest heterogeneity in the remaining biomass among the study areas positioned along the salinity gradient was found close to days 30 (5mm) and 40 (1mm). The overall results indicate that the relationship between leaf decay rate and salinity depends on the decay time considered (k 15, k 30 or k 60) and, for the later stages (k 60), also on the leaf-bag mesh size. This implies that the use of leaf litter decay rates as a functional indicator in transitional waters will need to take into consideration the factor location in the salinity gradient and leaf litter stage at which the decay rate is determined. The differences between the decay rates with the mesh size acted mainly at the level of the absolute k value and not at the level of the pattern along the salinity gradient. Even so, the data obtained at the mouth of the estuary, in the area closest to a fully marine environment, indicated that after the initial biomass loss through leaching, P. australis decayed either very slowly, in the 5mm, or not at all, in the 1mm mesh bags. [Copyright &y& Elsevier]

Abstract: The paper aimed to study the influence of the aeration rate on nitrogen dynamics during the composting of Blackwater sludge with sawdust. The increased aeration was responsible for an increase in ammonia emissions and for the decrease in nitrogen losses through leaching. At high aeration rates, losses of nitrogen in leachates and as ammonia in exhaust gas accounted for 90.99%of the nitrogen removed fromthe material. At low aeration rates, those accounted for 47.85%of the nitrogen removed fromthe material. The nitrification rate was found to be proportional to the mean content of NH4 +/NH3 in the material, i.e., initial NH4 +/NH3 plus NH4 +/NH3 released by ammonification minus the losses in leachates and in exhaust gas. The aeration rate was shown to be a main parameter affecting nitrogen dynamics during composting, since it controlled the ammonification, the ammonia emission and the nitrification processes. [Copyright &y& Elsevier]

Abstract: A dynamic leaching test (DLT) was developed and used to evaluate the leaching of toxic substances for electronic waste in the environment. The major components in personal computers (PCs) including motherboards, hard disc drives, floppy disc drives, and compact disc drives were tested. The tests lasted for 2 years for motherboards and 1.5 year for the disc drives. The extraction fluids for the standard toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) were used as the DLT leaching solutions. A total of 18 elements including Ag, Al, As, Au, Ba, Be, Cd, Cr, Cu, Fe, Ga, Ni, Pd, Pb, Sb, Se, Sn, and Zn were analyzed in the DLT leachates. Only Al, Cu, Fe, Ni, Pb, and Zn were commonly found in the DLT leachates of the PC components. Their leaching levels were much higher in TCLP extraction fluid than in SPLP extraction fluid. The toxic heavy metal Pb was found to continuously leach out of the components over the entire test periods. The cumulative amounts of Pb leached out of the motherboards in TCLP extraction fluid reached 2.0g per motherboard over the 2-year test period, and that in SPLP extraction fluid were 75–90% less. The leaching rates or levels of Pb were largely affected by the content of galvanized steel in the PC components. The higher was the steel content, the lower the Pb leaching rate would be. The findings suggest that the obsolete PCs disposed of in landfills or discarded in the environment continuously release Pb for years when subjected to landfill leachate or rains. [Copyright &y& Elsevier]

Abstract: Leaching studies using spent petroleum catalyst containing Ni, V and Mo were carried out using two different acidophiles, iron oxidizing (IOB) and sulfur oxidizing (SOB) bacteria. XRD analysis proved the existence of V in oxide form, Ni in sulfide form, Mo both in oxide and sulfide forms, and sulfur in elemental state. Both bacteria showed similar leaching kinetics at the same leaching parameters, such as pH, nutrient concentration, pulp density, particle size and temperature. The dissolution kinetics for Ni and V was much higher than Mo. Bioleaching kinetics was observed to follow dual rates, initially faster followed by a slower rate. So, dissolution mechanism was based on surface- and pore-diffusion rate. The dissolution process was found to follow 1st order kinetics. Unified dissolution rate kinetics equations were developed using 1st order rate kinetics. Various thermodynamic parameters were also calculated. Rate determining step for both the bacteria were evaluated and the average D 1 (surface) and D 2 (pore) values were found to be around 7×10−9 and 1×10−10 cm2 respectively. The lower value of D 2 suggested that the pore diffusion is the rate determining step during bioleaching process. [Copyright &y& Elsevier]

Abstract: Precipitation and throughfall fluxes of major ions, nutrients (C, N, P), and metals (Al, Fe, Mn), and the chemical composition of litter fall and living plant tissue in Norway spruce stands (the Bohemian Forest; Czech Republic), were used to evaluate how microbial processes and decay of plant tissue in canopies influence canopy leaching (CL) of elements. Proton exchange for Mg2+, Ca2+, and K+ in decaying biomass and co-transport of Ca2+ and K+ out of plant cells with organic acid anions were the most likely processes contributing to CL of base cations. The CL of total P and N (and also NO3 −) was minor. Important proportions of the N and P mineral forms were transformed to organic forms by microbial processes (primary and bacterial production), with the respective CL of −13.9 and 16.4 mmol m−2 yr−1 for NH4 + and organic N, and −0.33 and 0.22 mmol m−2 yr−1 for dissolved reactive P (DRP) and organic P. Most of particulate P and N in throughfall (∼90%) originated from microbial DRP and NH4 + transformations, but particulate C mostly came from the fragmentation of plant tissue (58%). Among metals, CL was not observed for Al, was small for Fe (0.3 mmol m−2 yr−1), and greatest for Mn (0.9 mmol m−2 yr−1) due to leaching from decaying tissue by acidic precipitation. [Copyright &y& Elsevier]

This study investigated VOC emissions from the largest petrochemical industrial district in Taiwan and recommended some control measures to reduce VOC emissions. In addition to the petrochemical industry, the district encompasses a chemical and fiber industry, a plastics industry and a harbor, which together produce more than 95% of the VOC emissions in the area. The sequence of VOC emission was as follows: components (e.g., valves, flanges, and pumps) (47%) > tanks (29%) > stacks (15%) > wastewater treatment facility (6%) > loading (2%) > flares (1%). Other plants producing high-density polyethylene (HDPE), styrene, ethylene glycol (EG), gas oil, and iso-nonyl-alchol (INA) were measured to determine the VOC leaching in the district. The VOC emissions of these 35 plants (90% of all plants) were less than 100 tons/year. About 74% of the tanks were fixed-roof tanks that leached more VOCs than the other types of tanks. To reduce leaching, the components should be checked periodically, and companies should be required to follow the Taiwan EPA regulations. A VOC emission management system was developed in state implementation plans (SIPs) to inspect and reduce emissions in the industrial district. [ABSTRACT FROM AUTHOR]

Abstract: Direct and indirect nitrous oxide (N2O) emissions and leaching losses from an intensively managed grazed pasture in the Ythan catchment, Aberdeenshire, UK, were measured and compared over a 17-month period. Simultaneous measurements of farm-wide leaching losses of N2O were also made and catchment-wide fluxes were estimated from existing N leaching data. The relative importance of direct and indirect N2O fluxes at the field, farm and catchment scale was then assessed. At the field scale we found that direct N2O emissions were low (1.2kgNha−1 year−1, 0.6% of N input) with indirect N2O emissions via drainage waters comprising a significant proportion (25%) of total N2O emissions. At the whole-farm scale, the N2O-N emission factor (0.003) for leached NO3-N (EF5-g) was in line with the IPCC''s recent downward revision. At the catchment scale, a direct N2O flux of 1.9kgNha−1 year−1 and an indirect flux of 0.06kgN2O-Nha−1 year−1 were estimated. This study lends further support to the recent downward revision of the IPCC emission factor for N2O arising from leached N in surface and ground waters (EF5-g) and highlights the need for multiple point sampling to ensure that the importance of indirect N2O losses via drainage waters is not misrepresented at the farm and catchment scales. [Copyright &y& Elsevier]

Continuous-monitoring applications are an important class of wireless sensor network (WSN) applications. These applications require periodic refreshed data information at the sink nodes. To date, this entails the need for the sensor nodes to continuously transmit in a periodic fashion to the sink nodes, which may lead to excessive energy consumption. In this paper, we show that continuous monitoring does not necessarily imply continuous reporting. Instead, we demonstrate that we can achieve continuous monitoring using an event-driven reporting approach. Building on this idea, we propose two new mechanisms that enable energy conservation in continuous-monitoring WSNs. The first mechanism can augment any existing protocol, whereas the second mechanism is conceived for cluster-based WSNs. With both mechanisms, sensor nodes only transmit information whenever they sense relevant data. To evaluate the efficiency of our proposals, the basic unscheduled transmission model and three well-known cluster-based protocols are used as baseline examples. In particular, new analytical models for conventional cluster-based systems and for our approach-enabled systems are complemented by simulations to present a quantified perspective of the potential benefits of the proposed reporting technique. We prove that significant energy conservation can be achieved using our reporting approach. [ABSTRACT FROM AUTHOR]

Abstract: The toxic glycoalkaloids produced by the potato plant (Solanum tuberosum L.) have previously been found in upper soil from a potato field during several months. Further insight into the fate of the glycoalkaloids is needed, as only little information about their degradation in soil is available. Degradation of the glycoalkaloid, α-solanine, has been followed for 42d in three agricultural soils with common texture and carbon contents. A similar degradation pattern was found in all soils, and the kinetics was well described by a sum of two first-order equations. Overall, degradation rates for the initial first reaction were in the range 0.22–1.64d−1. Estimated half-lives were in the range 1.8–4.1d for the three top soils at 15°C; the fastest degradation was observed in the sandy soil. The major proportion of α-solanine in the sandy soil was degraded by the fast process, while the proportion was lower for the two other soils. Fast degradation appeared to be related to the presence of low amount of sorbents. Additionally, degradation was followed at 5°C in A- and C-horizon soil from the sandy location, and for both horizons the half-lives were of similar length (4.7–8.7d). For the slow process, degradation rates were in the range 0.000–0.123d−1, and residuals were still present in all soils and all temperatures at the end of the experiment (d 42). Overall, fast degradation was found in both top- and subsoil even at low temperatures, and the risk for α-solanine leaching to the groundwater appears to be low. [Copyright &y& Elsevier]

The performance of a multisurface sorption model approach, composed of well-accepted surface complexation models in combination with published "generic" parameter sets, is evaluated for its possible use in risk assessment. For that purpose, the leaching of a broad range of potential soil contaminants (Ni, Cu, Zn, Cd, Pb, Ba, Cr, Co, Mo, V, Sn, Sb, S, An, Se) from eight diffusely and industrially contaminated soils is predicted simultaneously without any parameter optimization. The model approach includes aqueous speciation in combination with sorption to organic matter (NICA-Donnan model), Fe/Al-(hydr)oxides (Generalized Two-Layer Model), and clay (Donnan model). Independent date generated by pH-static leaching experiments, performed with individual subsamples over a wide pH range (pH 0.4-12), provide a sensitive evaluation of the model performance. Root-mean-squared error values between predicted and measured log concentrations over the entire pH range. RMSElog, are <0.5 for Cu, Ni, Cd, Co, S, and Se, and RMSElog <1 for Zn, Ba, Cr, Pb, Sn, Mo, Sn and As. The approach without parameter optimization has led to recommendations for further research with particular emphasis on identification of leaching mechanisms for Pb, Mo, Sb, and V and further expansion of the data sets to reduce the uncertainty of the available generic sorption parameters for Sn, Sb, Ba, Cr, and V. [ABSTRACT FROM AUTHOR]

Leachate metal pollutant concentrations produced from different asphalt and concrete pavement surfacing materials were measured under controlled laboratory conditions. The results showed that, in general, the concentrations of most metal pollutants were below the reporting limits. However, dissolved chromium was detected in leachate from concrete (but not asphalt) specimens and more strongly in the early-time leachate samples. As the leaching continued, the concentration of Cr decreased to below or close to the reporting limit. The source of the chromium in concrete pavement was found to be cement. The concentration of total Cr produced from leachate of different cement coming from different sources that was purchased from retail distributors ranged from 124 to 641μg/L. This result indicates that the potential leachability of dissolved Cr from concrete pavement materials can be reduced through source control. The results also showed that the leachability of dissolved Cr in hardened pavement materials was substantially reduced. For example, the concentration of dissolved Cr measured in actual highway runoff was found to be much lower than the Cr concentration produced from leachate of both open and dense graded concrete pavement specimens under controlled laboratory study. It was concluded that pavement materials are not the source of pollutants of concern in roadway runoff; rather most pollutants in roadway surface runoff are generated from other road-use or land-use sources, or from (wet or dry) atmospheric deposition. [Copyright &y& Elsevier]

Diuron is frequently detected in some drinking water reservoirs under the Burgundy vineyards, where organic amendments are applied. The environmental effect of these amendments on pesticide transport is ambiguous: on the one hand it could enhance their retention by increasing soil organic carbon content; on the other hand, dissolved organic matter (DOM) could facilitate their transport. Elutions were performed using columns packed with glass beads in order to investigate DOM¿diuron interactions, and the possible co-transport of diuron and DOM. Four organic amendments (A, B, C and D) were tested; C and D were sampled at fresh (F) and mature (M) stages. An increase in diuron leaching was observed only for A and DF amendments (up to 16% compared to the DOM-free blank samples), suggesting a DOM effect on diuron transport. These results could be explained by the higher DOM leaching for A and DF compared to B, CF, CM and DM increasing diuron¿DOM interactions. These interactions seem to be related to the aromatic and aliphatic content of the DOM, determining formation of hydrogen and non-covalent bonds. The degree of organic matter maturity does not seem to have any effect with amendment C, while a reduction in diuron leaching is observed between DF and DM. After equilibrium dialysis measurement of diuron¿DOM complexes, it appeared that less than 3% of the diuron applied corresponded to complexes with a molecular weight >1000 Da. Complexes <1000 Da could also take part in this facilitated transport. [Copyright &y& Elsevier]

The uptake and persistence behaviour of the insecticide imidacloprid in tomato plants treated by (i) foliar spray application and (ii) soil irrigation was studied using two plant uptake models. In addition to a pesticide deposition model, a dynamic root uptake and translocation model was developed, and both models predict residual concentrations of pesticides in or on fruits. The model results were experimentally validated. The fraction of imidacloprid ingested by the human population is on average 10−2 to 10−6, depending on the time between pesticide application and ingestion, the processing step, and the application method. Model and experimentally derived intake fractions deviated by less than a factor of 2 for both application techniques. Total imidacloprid residues were up to five times higher in plants treated by foliar spray application than by soil irrigation. However, peeling tomatoes treated by spray application reduces the human intake fraction by up to three orders of magnitude. Model calculations suggest that drip-irrigation in a closed hydroponic system minimizes worker and consumer exposure to pesticides and prevents runoff of pesticide by spray drift and leaching into the environment. [Copyright &y& Elsevier]

Pesticide degradation models are compared which simulate the response of biofilters for treatment of pesticide-contaminated waste water to time-irregular pesticide supply in which the pesticide is used for growth and mineralized. Biofilter microcosms containing a mixture of straw, peat and soil and harboring micropopulations which uses the herbicide linuron for growth, were irrigated with linuron for 28weeks with a stop in its supply between week 12 and 17. Matrix samples were regularly taken to assay linuron mineralization. A first-order approximation of the Monod model was used to simulate the observed mineralization data, while an inverse modeling framework combining a sensitivity analysis (Morris Sensitivity Analysis) with an inverse modeling approach (Shuffled Complex Evolution Metropolis) adopted to parameterize the model. Lag times in linuron mineralization decreased during the initial weeks of linuron irrigation but increased after supply of linuron ceased. The model well-simulated the lag time dynamics which were related to the dynamics of the predicted linuron-degrading population size in the microcosms. It was predicted that the population size decreased at a rate of 0.031d−1 after pesticide supply ceased to reach its initial population size after 25weeks. We conclude that modeling pesticide degradation in biofilters should incorporate biomass dynamics in case the pesticide is used as C-source. First-order approaches without incorporating biomass dynamics could lead to underestimation of the risk of pesticide leaching. [Copyright &y& Elsevier]

In terms of resource recovery and environmental impact, melting furnace fly ash (MFA) is attracting much attention in Japan due to its high metal content. The study aims to obtain fundamental information on using a water extraction method not only to concentrate valuable rare metals but also to remove undesirable substances such as chlorine for their recovery from MFA. The composition and leaching characteristics of MFA was investigated. The results revealed that the metal content in MFA is nearly equal to raw ore quality. The content of Ag, In, Pd, Pb, and Zn is, in fact, higher than the content of raw ore. As for leaching behavior, Ag, Bi, In, Ga, Ge, Sb, Sn, and Te showed the lowest release at a neutral pH range. Pd was leached constantly regardless of pH, but its concentration was quite low. On the other hand, most of the Tl was easily leached, revealing that water extraction is not appropriate for Tl recovery from MFA. Major elements Cl, Ca, Na, and K, occupying about 70% of MFA, were mostly leached regardless of pH. Base metal elements Cu, Pb, and Zn showed minimum solubility at a neutral pH. The leaching ratio of target rare metal elements and base metal elements suggests that the optimal pH for water extraction is 8–10, at which the leaching concentration is minimized. The water extraction process removed most of the Cl, Ca, Na, and K, and the concentration of rare metals and base metals increased by four or five times. [Copyright &y& Elsevier]

The article discusses research that quantified the leaching of turkey litter constituents from uncovered stockpiles into soils. Poultry are fed trace elements such as arsenic that can infiltrate the soil and contaminate shallow groundwater. The stockpiles examined in this study were located on Orangeburg loamy sand. Soil samples were analyzed for pH, electrical conductivity, total carbon, and dissolved organic compounds. Trace elements, including arsenic, copper, and zinc, were also quantified. It was discovered that groundwater used for drinking purpose that is obtained from farms with a history of litter stockpiling on bare soil should be monitored for contamination.