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.

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).

Soil pollution with trace elements is a growing problem with serious environmental impacts and developing strategies to reduce those impacts is a high priority. The objectives of this study were to assess the role of sulfur (S) in reducing the phytotoxic effects of copper (Cu) and the appearance of oxidative stress due to excess Cu in the growth medium and to assess the potential of guinea grass for Cu phytoremediation. The experiment was carried out in a greenhouse, where the forage grass Panicum maximum cv. Tanzânia was grown with a nutrient solution containing combinations of three S concentrations (0.1, 2, and 4 mmol L⁻¹) and four Cu concentrations (0.3, 100, 500, and 1,000 μmol L⁻¹) using a 3 × 4 factorial design in complete randomized blocks with four replicates. The following variables were measured: shoot and root dry mass production, leaf and tiller number, S and Cu concentrations in diagnostic leaves and roots, H₂O₂, lipid peroxidation, and proline levels in the diagnostic leaves. Very high Cu availability (1,000 μmol L⁻¹) that resulted in Cu concentration higher than 60 mg kg⁻¹in diagnostic leaves caused more than 50 % reduction in shoot and root dry mass production about 30–40 % in the number of leaves and tillers around 20 % increase in lipid peroxidation and more than 10 times increase in proline production. Plants properly fed with S showed mitigation to Cu toxicity. Guinea grass showed promise as an agent in the phytoremediation of Cu-polluted areas.

A novel method of acid orange 7 (AO7) removal has been developed via the deposition of plasma-polymerized allylamine (ppAA) films on quartz particles. ppAA films were deposited at a power of 25 W, allylamine flow rate of 4.4 sccm and polymerization time of 5 to 60 min. Polymerization time had a significant effect on surface chemistry where the XPS nitrogen concentration, XPS C-O, C-N concentration, isoelectric point and the number of positively charged groups per nm²all increased with increasing polymerization time. Increasing polymerization time increased AO7 adsorption due to greater concentrations of positively charged amine groups on the surface. The pH and initial AO7 concentration were varied to investigate their effect on AO7 adsorption. Increasing the initial AO7 concentration increased adsorption for all polymerization times. pH had a significant effect on AO7 adsorption with maximum adsorption at pH 3 and significantly less at pH values of 5–9. Regeneration of ppAA-coated quartz particles for up to 4 cycles using pH 12 Milli-Q water resulted in only slight losses in adsorption capacities. ppAA-coated particles have shown to successfully remove AO7 dye from solution and therefore demonstrate potential for use in the treatment of industrial dye wastestreams.

The effects of radiation pollution on the population diversities and metabolic characteristics in soil microorganisms from radiation pollution areas were investigated. Microbial diversities were determined by using methods of cultured isolates and carbon source utilization on Biolog EcoPlate™. The results showed that radiation changed soil microbial community structure and function. With the increasing of radiation pollution, the number of bacteria and actinomycetes declined gradually. Carbon utilizations of microbial community were significant ly different from each other (ρ < 0.05). Microbial activity decreased gradually; Simpson index and McIntosh index increased, but Shannon-Wiener index was not significant different; the major utilized substrates indicated that microbes more tend to use carboxylic acids and polymers as carbon sources, instead of carbohydrates. In conclusion, the community composition of microorganisms as well as population diversity in soils was impacted obviously by radiation pollution.

The medium most directly affected by anthropic contamination is soil and, hence, groundwater (saturated and unsaturated zones). In the phytoremediation process, the direct absorption of soil contaminants through the roots is a surprising pollutant removal mechanism. Plants can act as a natural filter of shallow groundwater contamination, controlling and reducing the vertical percolation of contaminants into the soil, and after reaching the level of the water table, the roots can absorb contaminants dissolved in the water, thus reducing the size of the plume and protecting receptor sites (water supply wells, rivers, lakes) from possible contamination. In the first phase of the research, assays were performed to evaluate the tolerance of plant species to the direct injection of a benzene solution into the roots. Subsequent experiments involved direct absorption and spraying. The aim of this study was to evaluate the potential for tolerance and reaction to high levels of benzene. Three plant species were used, an herbaceous ornamental plant (Impatiens walleriana), a fern (Pteris vittata), and forage grass (Brachiaria brizantha). At the end of the study, the surface changes caused by VOCs (aerial structures) of benzene were evaluated, using an environmental scanning electron microscope (ESEM) to identify possible mechanisms of resistance of the plant to air pollution, i.e., hydrocarbon pollution. The plant material used here was young plant species selected for study. For the analysis by gas chromatography (GC), the plant material was separated into aerial (stem, leaves, and flowers) and underground parts (roots). A comparison of the benzene content in different parts of the plant indicated a higher concentration in the stem + leaves, followed by the roots, which is justified by its translocation inside the plant. P. vittata showed low uptake (5.88 %) mainly in the root and (<2 %) in the leaves, which was also observed in the tolerance experiment, in which visual symptoms of toxicity were not observed. I. walleriana showed benzene removal rates of approximately 18.7 % (injection into the soil) as a result of direct absorption through the roots. After the treatment was suspended, I. walleriana gradually reacted to the detoxification process by recovering its stem stiffness and normal color. B. brizantha showed intermediate behavior and did not react to the detoxification process.

Biochar produced from malt spent rootlets was employed for the removal of Hg(II) from pure aqueous solutions. Batch experiments were conducted at 25 °C. The optimum pH value for Hg(II) sorption onto biochar was 5. Biomass dose and contact time were examined to determine sorption kinetics and equilibrium capacity constants. The increase of biochar dose resulted in higher sorption efficiency. After a 24-h contact time at biochar concentrations of 0.3 and 1 g/L, the Hg(II) removal was 71 and 100 %, respectively. Based on the sorption kinetic data, the biochar sorption capacity for mercury reached its maximum after 2 h; 33 % of Hg(II) was removed within the first 5 min. Based on the isotherm data, the maximum biochar sorption capacity for Hg(II) was 103 mg/g. Finally, HCl, EDTA, NaCl, HNO₃, H₂SO₄, and distilled water leaching solutions were tested for Hg(II) desorption with HCl being the most effective.

A simple, rapid, sensitive, and inexpensive dispersive liquid–liquid microextraction method was developed for the determination of trace amounts of copper by flame atomic absorption spectrometry (FAAS). N,N′-bis-(2-hydroxy-5-bromobenzyl)-2-hydroxy-1,3-diiminopropane was used as the chelating ligand. Several analytical parameters affecting the microextraction efficiency such as, sample pH, volume of extraction solvent (carbon tetrachloride), concentrations of the chelating ligand and NaCl, and sample volume were investigated and optimized. The effect of the interfering ions on the recovery of copper was also examined. Under the optimum conditions, the detection limit (3σ) was 0.75 μg L⁻¹for copper with a sample volume of 10 mL, and a preconcentration factor of 20 was achieved. The relative standard deviation (R.S.D) for ten independent determinations of a 10 μg L⁻¹solution of Cu(II) was 2.3 %. In order to verify the accuracy of the developed method, different certified reference materials (SLRS-5, QCS-19, Rice flour unpolished high level of Cd NIES 10c) were analyzed and the results obtained were in good agreement with the certified values. The proposed method was applied to tap water, river water, seawater, rice flour, and wheat flour samples. The percentage recovery values for spiked water samples were between 95.4 and 108.4.

Laoyingshan town lead zinc mine is one of the important zinc production centers in Guizhou province, China. The cadmium (Cd) is one of the mineral resources associated of lead zinc mine. The exploitation and uses of lead zinc mine would lead to Cd pollution to the environment. Soil Cd concentrations in this area are elevated by 30–50 times compared to the national background value in soil which is 0.279 mg kg⁻¹. In situ air Cd concentrations air/soil Cd fluxes were measured at 26 sampling sites in Laoyingshan town by moss bag from Jan. to Sep. 2005. The results showed that the average Cd concentration of total suspended particulates (TSP) and soil were 5.3 and 4.6 times higher than those measured at downwind direction 10 km due to a large amount of Cd emission from traditional melting. The results showed a clear decreasing trend along with the distance increasing from the pollution source for all the study parameters, namely cadmium contents in soil and TSP and deposition rate determined using moss-bag method. The results are consistent with the studied results previously. The correlations between Cd fluxes and soil show the relationship between the content in atmospheric TSP and spatial distribution of deposited heavy metal. The authors found that air spread is the major route of Cd pollution.