Preindustrial (1850s) and future (2060) streamwater chemistry of an anthropogenically acidified small catchment was estimated using the MAGIC model for three different scenarios for dissolved organic carbon (DOC) concentrations and sources. The highest modeled pH = 5.7 for 1850s as well as for 2060 (pH = 4.4) was simulated given the assumption that streamwater DOC concentration was constant at the 1993 level. A scenario accounting for an increase of DOC as an inverse function of ionic strength (IS) of soilwater and streamwater resulted in much lower preindustrial (pH = 4.9) and future recovery to (pH = 4.1) if the stream riparian zone was assumed to be the only DOC source. If upland soilwater (where significant DOC increase was observed at −5 and −15 cm) was also included, DOC was partly neutralized within the soil and higher preindustrial pH = 5.3 and future pH = 4.2 were estimated. The observed DOC stream flux was 2–4 times higher than the potential carbon production of the riparian zone, implying that this is unlikely to be the sole DOC source. Modeling based on the assumption that stream DOC changes are solely attributable to changes in the riparian zone appears likely to underestimate preindustrial pH.

This paper presents a comprehensive analysis of the pollutant emissions and intensity from Canada’s power stations. An analysis of National Pollutant Release Inventory (NPRI) and site generation data shows significant variability with the dominant emissions pathway being point-source air emissions. In general, power stations are a very small fraction of Canada’s direct facility and estimated diffuse emissions, as well as showing significant variability of pollutant intensities per megawatt or megawatt hour of capacity or generation. The evidence also suggests that increased scale does not lead to a lower pollutant intensity, and that transfers and disposal pollutant loads are substantial, often representing most of the total reported pollutants. Overall, this study provides a valuable insight into the current status of pollutant intensities from Canada’s power stations, possible improvements to the NPRI and a valuable benchmark for future studies and international comparisons.

The sulfate input and the occurrence of dryout and rewetting may promote the production of toxic methylmercury (MeHg) in a constructed wetland, Stormwater Treatment Area 2 (STA-2) in South Florida. Therefore, the aim of this study was to investigate the influences of inflow water quality, especially inflow sulfate, and the dryout and rewetting cycle on the mercury (Hg) methylation in three independent cells of STA-2 from 2000 to 2007. Because the majority of the total Hg (THg) bioaccumulated in fish is in MeHg form, THg concentration in mosquitofish was used to present the MeHg production in STA-2. Mosquitofish THg in Cells 1 and 2 (with median values of 0.101 and 0.02 mg/kg, respectively) were significantly higher than in Cell 3 and inflow (both with a median value of 0.01 mg/kg). The difference in mosquitofish THg among the three cells was likely a result of the drying and rewetting cycles occurred in Cells 1 and 2, which promoted the Hg methylation. Inflow sulfate, inorganic Hg, and chloride exhibited a significant correlation with mosquitofish THg in cells, suggesting that these inflow variables played important roles on the Hg methylation. The results indicate that inflow sulfate may likely stimulate sulfate-reducing bacteria and subsequently lead to produce MeHg in the three cells. Our findings in this study indicate that preventing the occurrence of dryout in wetland will help to decline the Hg methylation, and sulfate input is a key factor to influence the Hg methylation in wetland.

We have developed a decision support system that prompts the user for site and contaminant characteristics from petroleum extraction and transportation processes and filters out those technologies that are most adequate for site remediation from the categories of remedial methods in its database. The computerized rule-based structure facilitates the evaluation and selection of the most applicable and feasible treatment technology for petroleum-contaminated soil on a site polluted from pipeline deterioration, which this paper presents as a case study. The technology-screening feature is a useful tool in the early evaluation phase of the soil remediation process and can assist specialists in the simulation of various scenarios. The system has accurately estimated pollutant migration and extent for preliminary soil investigations and provided recommendations in accordance with the current remedial actions taken at these petroleum-contaminated sites. The decision elaboration is close to the situations often encountered in real life.

In agricultural areas, pesticides can enter receiving waterbodies by means of agricultural runoff and pollute these systems. Constructed wetlands are capable of removing several pollutants including pesticides. Unfortunately, few studies are from South America, and therefore, information is urgently needed on pesticide mitigation in agricultural runoff by native plants. To this aim, an experimental setup of polypropylene tubs was used, which were planted with two types of native plants (Nymphaea amazonum and Eleocharis mutata). Mesocosms were exposed to low (10 μg/l) and high (30 μg/l) target concentrations of lambda-cyhalothrin, while for imidacloprid, a low (60 μg/l), high (180 μg/l), and an extra high (1,000 μg/l) dose, were applied using batch experiments of 2 weeks each. Removal efficiencies for lambda-cyhalothrin from the water phase showed 100 % removal at 72 h for both low and high target concentrations for N. amazonum mesocosms, while for E. mutata mesocosms, a 100 % removal was observed at 48 h for mesocosms exposed to low target concentrations and for high target concentrations at 72 h. For imidacloprid, a 100 % removal was observed for E. mutata and 86 % for N. amazonum mesocosms exposed to low target concentrations (60 μg/l) at 216 h. For the highest dose (1,000 μg/l), the removal efficiency was on average 72 % at 216 h for both types of mesocosms. Statistical two-way ANOVA analysis (α = 0.05) showed that the removal of lambda-cyhalothrin was independent of the dose applied and the plant type, while for imidacloprid, removal was dependent on the dose applied and independent of the plant type. After the experimental period, analyses of the plants and sediment showed that 48.5 % of the applied amount of lambda-cyhalothrin was detected in the sediment and 0.4 % in plant material (shoots and leaves), while the amount in roots was below the limit of detection for N. amazonum mesocosms. For E. mutata mesocosms, 44.6 % of lambda-cyhalothrin was detected in sediment and 0.5 % in roots. For N. amazonum mesocosms, 78.9 % of the applied amount of imidacloprid was retained in plants (plant material and roots) and 17.31 % in sediment, while for E. mutata mesocosms only 0.5 % of imidacloprid was detected in plant material and roots. In this experiment, the DT₅₀of lambda-cyhalothrin in the water phase of both types of mesocosms was on average 1 day, while for imidacloprid, this was calculated to be around 1–10 days. The results obtained provide necessary information for the construction of a field scale wetland capable of efficient removal of pesticides in agricultural runoff.

We present the study of atrazine, the pesticide separation using the typical thin film composite (TFC) membranes, made up of polyamide formation between m-phenylenediamine (MPDA) and trimesoyl chloride (TMC) on the polysulfone membrane matrix. The unreacted acyl moieties in TFC membranes are chiefly responsible for the preferential rejection of bivalent counter ion (SO₄ ⁼) due to their residual charges compared to monovalent (Cl⁻) ion. These two low-pressure-driven membranes show the similar trend as salt and organic markers. Changing the feed matrix is also an interesting direction to improve the performance apart from choosing the membrane. This approach sheds light on the separation behaviour with the addition of biosurfactant. Biosurfactant-mediated filtration showed better performance of the membranes, though it depends on the nature of membranes. The membranes having more porous (in terms of organic markers) structure showed improvement in separation of atrazine. The increase in separation 20.29 % is observed for 200 mg/L biosurfactant for Memb-I, whereas 13.81 % increase is observed for Memb-II.

Soils that are exposed to floodwaters because of shallow groundwater and periodical wetlands are, to a large extent, exposed to contamination by organic and inorganic compounds. These are mainly compounds that have drifted along with the inflow of heavily laden floodwater and are produced within the soil profile by the anaerobic transformation of organic matter. Heavy metals and polycyclic aromatic hydrocarbon (PAH) compounds are absorbed by the soil of the floodwaters, and moving in the soil profile, they pose a threat to groundwater. What is more, after a flood, they may be absorbed by the crops. This paper focuses on the effects of Odra River (Poland) floods, heavy metals, and PAHs on soil and the possibilities of the migration of these pollutants into the soil profile. In the tested sludge samples of floodwater and soil, there were no abnormal concentrations of heavy metals, but the flooding time positively affected the amount listed in the test samples. Concentrations of PAHs increased, but they also exceeded the standards for arable soils in the case of single compounds.

In this study, the concentration-dependent joint action of chromium (Cr) and salt (NaCl), two important environmental stressors, was examined in aquatic plants. Ceratophyllum demersum L. plants were exposed to Cr (0–10 mM) for 5 days in the presence and absence of NaCl (0–500 mM). The effect of Cr, Na, and Cl accumulations on certain biological parameters (water content, ion leakage, relative growth rate, photosynthetic pigments, and protein and proline contents) was determined. Furthermore, the interactive effects of NaCl and Cr were evaluated using a mathematical model developed on the basis of the theory of probabilities. The highest Cr accumulation (0.42 mmol g⁻¹) was found in plants treated with 10 mM Cr + 125 mM NaCl. Treatment with 125 mM NaCl resulted in an increase in Cr accumulation compared with that in the control. However, 250 and 500 mM NaCl concentrations decreased Cr accumulation. Proline and water contents were not affected by increasing Cr concentration. However, NaCl did have a significant effect on any of the studied parameters. Furthermore, the interactive effects of Cr and NaCl on all studied parameters except for proline and water contents were determined. Except for photosynthetic pigments and proline content, effect of NaCl was higher than Cr on all studied parameters. The interactive effects were mostly antagonistic or additive. However, the mode of action for ion leakage was synergistic or additive. These results suggest that the coexistence of NaCl and Cr in aquatic ecosystems does not pose an additional ecological risk for aquatic plants.

Chemical stabilization is a cost-effective, environmentally friendly, in situ remediation technology based on the application of organic and/or inorganic amendments to reduce soil metal bioavailability. Our objective was to assess the early short-term effects of organic amendments (sheep manure—SHEEP, poultry litter—POULTRY, cow slurry—COW, paper mill sludge mixed with poultry litter—PAPER), in sterilized and non-sterilized form, on the microbial and chemical properties, as well as on the phytotoxicity, of a Cd, Pb and Zn contaminated soil. Our results provide useful information regarding (1) the effectiveness of amendments for chemical stabilization of mine soil and (2) the impact of microbial populations present in the amendments on soil native microbial communities. Microbial populations present in the amendments did not substantially modify soil microbial functional diversity, as reflected by Biolog EcoPlates™ data, except for PAPER-amended soils. We observed a good correlation between lettuce root elongation (phytotoxicity bioassay) and Cd, Pb, and Zn CaCl₂-extractable concentrations in soil. SHEEP and PAPER amendments were particularly effective at increasing soil pH and reducing metal bioavailability and phytotoxicity, while POULTRY and COW led to higher values of soil microbial properties (respiration and functional diversity). Beneficial effects observed under POULTRY at the beginning of the experiment, due to the presence of easily degradable organic matter, were partially lost over time. Our results emphasize the importance of the early monitoring of soil properties (microbial and chemical) and phytotoxicity to properly identify bottlenecks during amendment selection for chemical stabilization, in terms of reduction in metal bioavailability and improvement in soil health.

The adsorption of microcystin-LR (MCLR) by biochar has never been well understood. For the first time, the unconventional adsorption of hydrophilic MCLR on wood-based biochars was comprehensively investigated as a function of biochar properties, environmental temperature, solution pH, coexisting dissolved organic matter (DOM), and polar organic competitors. High-temperature-prepared biochar from 700 °C (BC-700) and low-temperature-prepared biochar from 300 °C (BC-300) were characterized with significantly different surface areas but similar alkaline nature. Despite a very low surface area, BC-300 exhibited very high adsorption capacity, which implies the important contribution of surface groups to biochar. MCLR adsorption on biochars was pH dependent and was strongly reduced by macromolecular DOM. Polycarboxylic aliphatic acids and 2-(2-hydroxyethyl) guanidinium cation, which are similar to specific structural groups in MCLR, exhibited an evident competitive effect. The results indicated that both carboxylic and guanidino groups of MCLR serve significant functions in MCLR adsorption to biochar. The adsorption mechanisms may be primarily related to the columbic attractions and the hydrogen bonding interactions between MCLR and biochar surface. In particular, the irreversible adsorption enhancement of MCLR was observed on BC-700, which suggests that biochar amendment can aid in immobilizing MCLR from water to sediment, thereby prolonging MCLR environmental fate in biochar-amended sediment.