Identifying the relative importance of stressors is critical for effectively managing and conserving freshwater aquatic ecosystems. However, variability in natural ecosystems and the potential for multiple stressors make understanding the effects of stressors challenging in the field. To address these challenges, we assessed four common stressors in the northeastern USA including acidification (pH), climate change (water temperature), salinization (Na and Cl), and nutrient addition using laboratory mesocosms. Each stressor was evaluated independently, with ten mesocosms assigned across a gradient of concentrations for each stressor (total N = 40). We then monitored the effects of the stressors on a model community consisting of periphyton, zooplankton, Northern watermilfoil (Myriophyllum sibericum), American ribbed fluke snail (Pseudosuccinea columella), and larval American bullfrogs (Lithobates catesbeianus). Aquatic stressors varied in the strength of their effects on community structure: Nutrient addition was the least influential stressor, with no significant effects. Acidification influenced periphyton biomass, but not higher trophic levels. Water temperature influenced primary productivity and survival of amphibian larvae, but not intermediate trophic levels. Finally, road salt led to decreases in productivity for all trophic levels included in our model systems. Our results support the findings of prior research, although the effects of acidification and nutrient addition were less pronounced in our study. Importantly, we found that road salt had the most far-reaching effects on a model aquatic community. Given that road salt is the most easily managed of the stressors we compared, our results indicate that improving the condition of freshwater aquatic ecosystems in the northeastern USA may be a feasible objective.

Artemisinin, an antimalarial compound derivated from the cultivated plant Artemisia annua L., is produced in situ through cultivation of A. annua under different climatic conditions. The bioactive compound artemisinin has been observed to spread to the surroundings as well as to leach to surface- and groundwater. To make better risk assessments of A. annua which is cultivated under varying climatic conditions, the temperature-dependent toxicity of artemisinin toward the green algae Pseudokirchneriella subcapitata and the macrophyte Lemna minor was evaluated at temperatures ranging from 10 to 30 °C. To include a possible effect of temperature on the degradation rate of artemisinin, artemisinin concentrations were measured during the experiment and toxicity was related to the time-weighted averages of exposure concentrations. The toxicity of artemisinin toward the macrophyte L. minor and the algae P. subcapitata increased with increasing growth rates, and we conclude that bioavailability plays a minor role in the observed relation between temperature and toxicity of artemisinin. The obtained results are important for possible future risk assessment of A. annua cultivation.

To remove phosphate from solution, a new class of sorbent based on chitosan bead (CB) was prepared using copper ion (Cu(II)) with/without a traditional crosslinking agent (glutaraldehyde [GLA]); these materials are referred to as CB-G-Cu and CB-Cu, respectively. Copper ions play a key role in the CB synthesis; these species crosslink each polymer chain, and during phosphate removal, they are the active functional group. Overall, 2.5 % (w/w) of chitosan is necessary to maintain the physical properties of the bead. In the FTIR spectra, adding GLA decreased the intensity of the amino group in chitosan, lowering the amount of copper in the CB. The maximum phosphate uptake (Q) for CB-Cu was 53.6 mg g⁻¹when calculated with the Langmuir isotherm, and the phosphate equilibrium was achieved in 12 h. Although the solution pH was not strongly affected, values below 7 are optimal for phosphate removal. The CB-Cu can be feasibly applied during a fixed column test, revealing that the phosphate breakthrough was 1.5 times higher than with CB-G-Cu.

Green Infrastructure (GI) practices have been identified as a sustainable method of managing stormwater over the years. Due to the increasing popularity of GI as an integrated urban water management strategy, most of the current catchment modeling tools incorporate these practices, as built-in modules. GI practices are also viewed as economically viable methods of stormwater management when compared to conventional approaches. Therefore, cost-benefit analysis or economics of GI are also emerging as obligatory components of modeling tools. Since these tools are regularly upgraded with latest advancements in the field, an assessment of tools for modeling stormwater management and economic aspects of GI practices is vital to developing them into more sophisticated tools. This review has undergone a three-phase process starting with 20 identified modeling tools available in the literature followed by a detailed review of a selection of ten most recent and popular modeling tools, based on their accessibility. The last phase of the review process is a comparison of the ten modeling tools along with their different attributes. The major aim of this review is to provide readers with the fundamental knowledge of different modeling tools currently available in the field, which will assist them with screening for a model, according to their requirements from the number of tools available. A secondary aim is to provide future research directions on developing more comprehensive tools for GI modeling, and recommendations have been presented.

Methane (CH₄) formation in wastewater treatment is linked to long residence times under anaerobic conditions such as those in sewers and primary treatment units. Emissions of this methane to the atmosphere can occur under turbulent flows and, potentially, during aeration in an activated sludge plant. An online, 8-week monitoring campaign of CH₄emissions and operational conditions was conducted to study emissions from a full-scale nitrifying activated sludge plant (ASP). Significant emissions were found throughout the aerated lane, with the highest values observed two thirds down the lane. Emissions had high diurnal and spatial variability, with values ranging from 0.3 to 24 g CH₄/h. No significant correlations were found between dissolved oxygen, aeration or influent loads. The results suggest that emissions are linked to upstream process conditions, with potential for methane generation in-lane due periods of limited oxygen availability. The dynamic oxygen profile observed suggests that aerobic and anoxic conditions coexist in the lane, leading to limited oxygen diffusion from the bulk liquid to the inner regions of the floc where anoxic/anaerobic layers may allow methanogenic microorganisms to survive. The average emission factor was 0.07 % of removed chemical oxygen demand, giving a total of 668 kg CH₄/year and 14,000 CO₂equivalents/year. The operational carbon associated with the energy requirements of the ASP increased by 5 %. With emerging legislation requiring the reporting of greenhouse gas emissions, the carbon impact may be significant, particularly as the industry moves towards a carbon-reducing future. Therefore, an adequate profiling of full-scale emissions is critical for future proofing existing treatment technologies.

Pharmaceutical agents, like diclofenac and acetaminophen, are sold without prescription leading to excessive use. These agents may reach water bodies through various routes and attain significant concentrations, posing a risk to hydrobiont health. Diverse studies have shown that during the biotransformation of these compounds, reactive metabolites and reactive oxygen species are produced which induce oxidative stress and damage to diverse biomolecules. However, toxicity studies that assess the effects of a mixture of contaminants are scarce, being very important as this is how they are actually in the environment. The present study aimed to evaluate the oxidative stress induced by mixture of diclofenac and acetaminophen on Cyprinus carpio and compare with the effect produced by these pharmaceuticals in isolation. A 96-h sublethal toxicity assay of the tested pharmaceuticals (isolated and in mixture) was performed and the following biomarkers were evaluated: lipid peroxidation, protein carbonyl content, and activity of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. The pharmaceuticals evaluated induce oxidative stress on C. carpio in isolated form and as a mixture, but the level of damage being dependent on the organ evaluated as well as the type of toxicant and form of exposure (in isolation or as a mixture).

A wide variety of semi-volatile organic chemicals (SVOCs) are still in use in agricultural practices. A proper understanding of the environmental fate and ecotoxicological risk associated with these compounds can aid decision making, particularly regarding product registration and licensing. The aim of this paper is to expand the use of a previously developed Multimedia Agricultural Fate and Risk Assessment Model (MAFRAM) to SVOCs by adopting the fugacity concept as a second criterion to the existing MAFRAM partitioning criterion (i.e., aquivalence). Volatilization processes from surface compartments into the atmosphere were also included. For example, the application of the generalized model was illustrated using an average annual application rate of 4.48 kg/ha of chlorpyrifos over a typical homogeneous region. Chlorpyrifos emissions were assumed to take place in three environmental compartments (i.e., soil, air, and aboveground plants) with fractions of 0.1, 0.3, and 0.6, respectively. The trends seen in the modeling results were in good agreement with the existing experimental data. Validation issues in MAFRAM were also discussed. Comprehensive experimental validation is unattainable because of the large scale of the areas covered, the lack of boundaries for the system considered, and the uncertainty in the input parameters.

Tungsten (W) concentrations were measured along with arsenic (As) in groundwaters from the Murshidabad district of West Bengal, India. Tungsten concentrations range from 0.8 to ~8 nmol kg⁻¹(0.15–1.5 μg kg⁻¹) in the circumneutral pH (average pH ~ 7.3) Murshidabad groundwaters, and attain concentrations as high as 14 nmol kg⁻¹(2.5 μg kg⁻¹) in local ponds (n = 2). Total dissolved As concentrations (AsT) range from 0.013 to 53.9 μmol kg⁻¹(<1 to 4,032 μg kg⁻¹), and As(III) predominates in Murshidabad groundwaters accounting for 70 %, on average, of As in solution. Tungsten concentrations in Murshidabad groundwaters are low compared to alkaline groundwaters (pH > 8) from the Carson Desert in Western Nevada, USA, where W concentrations are reported to reach as high as 4,036 nmol kg⁻¹(742 μg kg⁻¹). Although W is positively correlated with As in groundwaters from the Carson Desert, it is not correlated with AsTor As(III) in Murshidabad groundwaters, but does exhibit a weak relationship with As(V) in these groundwaters. Surface complexation modeling indicates that pH related adsorption/desorption can explain the geochemical behavior of W in Murshidabad groundwaters. However, the model does not predict the high As concentrations observed in Murshidabad groundwaters. The high As and low W concentrations measured in Murshidabad groundwaters indicate that either As and W originate from different sources or are mobilized by different biogeochemical processes within the Murshidabad aquifers. Mobilization of As in Murshidabad groundwaters is presumed to reflect reductive dissolution of Fe(III) oxides/oxyhydroxides and release of sorbed and/or coprecipitated As to the groundwaters. Multivariate statistical analysis of groundwater composition data indicate that W is associated with Mn and Cl⁻, which may point to a Mn oxide/oxyhydroxide, clay mineral, and/or apatite source for W in the Murshidabad sediments.

During this study, the effect of applying several types of treated domestic wastewater on the translocation and accumulation of organic and inorganic micropollutants in soil and radish plants (Raphanus sativus L.) was examined. Primary (PTW), secondary (STW) and tertiary (TTW) treated wastewater as well as tap water (TW) were used for the irrigation of radish plants for a period (transplantating and harvesting) of 67 days. Higher concentrations of polycyclic aromatic hydrocarbons (PAHs) were observed in soils irrigated with PTW. The concentration of PAHs in radish roots ranged between 107.6 ± 12.1 μg/kg for plants irrigated with TTW and 124.1 ± 17.7 μg/kg for plants irrigated with PTW. The root concentration factors (RCFs) expressed as the ratio of PAH concentration in the root mass (dry weight) to the residual concentration in the soil varied from 1.6 to 1.9 indicating a higher accumulation of PAHs in the edible part of radishes than soil. Heavy metals were not detected in the wastewaters utilised and, as a result, no accumulation was found in either the soil or plants in comparison with tap water. RCFs for heavy metals were calculated between 0.91 and 0.99, 0.49 and 0.66, 0.004 and 0.005 for Cu, Zn and Ni, respectively. The results showed that radishes have the ability to concentrate PAHs when they are present in the wastewater and this could have associated health risks.

This work focuses on the effects of two commercial formulations of dispersants on juvenile turbot after 48 h of contamination and 15 days of recovery. Oxidative stress, gill, and immune functions were assessed in seven conditions: exposition to the water-soluble fraction of an oil, mechanical dispersion, two dispersants alone, two types of chemical dispersion and a control group. In the contaminated groups, nominal concentrations of oil and dispersants were 66 and 3.3 mg L⁻¹, respectively. Dispersants alone had weak effects; the soluble fraction induced leucopenia and gill alteration. Chemical and mechanical dispersion induced similar effects. After contamination, a principal component analysis showed two distinct areas: the first one included the control and dispersants groups, the second one dispersion of the oil. After the 15-day recovery period, it was not possible to differentiate the groups. This study shows that, in the experimental conditions tested, the dispersion, either chemical or mechanical, enhances the consequences of exposure to crude oil without long-lasting consequences.