Suspended sediments can decrease the apparent bio-concentration factor of organic pollutants through adsorption. However, whether this process also weakens the toxicity of organic pollutants to non-target aquatic organisms is not clear. Therefore, natural sediments were chosen as suspended sediment examples in this research applying atrazine as the target pollutant and Brachydanio rerio (more recently, Danio rerio (Zebrafish)) as the target organism to conduct acute toxicity experiments. The concentration of atrazine in aqueous solution was measured as a time series. Results show that without suspended sediments, the 96-h LC₅₀of atrazine to Brachydanio rerio is 29.06 mg/l at 95 % confidence interval (24.41 to 40.70 mg/l). For suspended sediments of 7500 and 15,000 mg/l, the LC₅₀(i.e., concentration resulting in 50 % mortality) equates to 30.74 and 39.51 mg/l, respectively, and the corresponding confidence intervals are between 27.17 and 40.91 mg/l and between 30.43 and 126.93 mg/l in that order. Probit analysis, which is a type of regression used to analyze binomial response variables, was applied using the Statistical Package for the Social Sciences. For the series of no suspended solids (SS), 7500 and 15,000 mg/l SS, the so-called no-observed-effective concentrations were 3, 9, and 15 mg/l, correspondingly. The uptake quantity and uptake rate of atrazine by B. rerio according to atrazine concentrations in the aqueous solution were computed. The research indicates that suspended sediments can decrease the absorbed rate of atrazine by B. rerio. Thus, suspended sediments weaken the acute toxicity of atrazine to B. rerio.

Degradation and fate of sulfamethazine (SMZ) were determined under aerobic and anaerobic conditions in soil with and without swine manure amendment. For both aerobic and anaerobic conditions, SMZ disappeared rapidly during the first 7 days followed by slow disappearance which may indicate that SMZ had become more persistent and less available. For soils receiving 100 mg/kg of SMZ, the percent of SMZ remaining in the soil after 63 days were between 25 and 60 %. Depending on the initial SMZ concentration, estimated half-lives for aerobic and anaerobic incubations ranged from 1.2 to 6.6 and 2.3 days to more than 63 days, respectively. Addition of manure (0.054 g/g soil) did not significantly affect the half-lives of SMZ. Inhibitory effects of SMZ on anaerobic microbial respiration were observed in unamended soil at concentrations of 50 mg/kg or higher, but only transient inhibitory effects were found in aerobic soil. Five to 22 % of the¹⁴C[phenyl]-SMZ added were extracted at the end of the incubations while 70 to 91 % of the¹⁴C were converted to bound (non-extractable) forms in both manure amended and unamended soil. Only 0.1 to 1.5 % of¹⁴C-SMZ was mineralized to¹⁴CO₂. Disappearance of SMZ in sterilized soil was not completely halted indicating possible contribution of abiotic processes to the disappearance of SMZ in soil.

As rice paddies are widespread sources of water pollution in the agricultural regions of the Asian monsoon area, a mechanistic understanding of nutrient loss from paddies is critical for water quality management. A 2-year experiment was conducted in a typical monsoon-affected rice field to improve our understanding of the impacts of rainfall and agricultural management practice on nitrogen (N) and phosphorus (P) loss. Samples of paddy drainage water were collected during rainfall events (n = 25) and analyzed for total N (T-N) and total P (T-P) concentrations. The impacts of rainfall (amount, duration, and intensity) and agricultural management practice (transplanting and fertilization) on the event mean concentration (EMC) and loss of nutrient were assessed using regression analyses. The results showed that T-N and T-P concentrations were affected by agricultural practice; meanwhile, loss of T-N and T-P was correlated with rainfall characteristics. Specifically, the EMC of T-N but T-P was negatively (p < 0.001) correlated with the number of days after agricultural practice in both years, which likely represents a decrease in nutrient availability in paddy water over time. Loss of T-N and T-P was positively (p < 0.01) correlated with rainfall amount, and this suggests that the rainfall-runoff process is a key driver of nutrient loss in the study area. Our results suggest that rainfall amount and days after transplanting need to be taken into account when estimating nutrient loss from rice paddies in monsoon regions.

Many studies have been conducted regarding the degradation of PAHs. One of the technologies that has been widely used is bioremediation due to its relatively low cost and greater efficiency for those compounds with structural complexity. Biotechnology has been used in several countries for many years and consists in the use of microorganisms (bacteria and fungi) to transform contaminants into inert substances, which is a result of the microbial activity from biochemical processes. This study aimed to develop a bioremediation methodology for the pollutant benzo[a]pyrene (B[a]P), which belongs to the group of PAHs. The potential use of a microbial consortium with Pseudomonas aeruginosa, Candida albicans, Aspergillus flavus, and Fusarium sp. for bioremediation was assessed. To confirm the pollutant reduction, quantifications of the samples were performed via gas chromatography–mass spectrometry (GC-MS). The contamination was prepared with a soil previously contaminated with B[a]P at the concentration of 3.74 mg kg⁻¹. The microbial consortium was added (16 μL g⁻¹), and samples were incubated for 42 days in an oven at 35 °C. The microbial growth curves showed representative differences between the samples in the presence and absence of the pollutant, demonstrating the possibility of bioremediation process. The final quantification of soil showed a mean concentration of 1.29 mg kg⁻¹, showed that 65.51 ± 0.95 % of the pollutant was degraded, which is an important and representative performance.

The development of nanotechnology has increased the amount of nanoparticles in the environment inducing pollution. In view of increasing amounts, their toxicity assessment becomes important. Aluminum oxide nanoparticles (Al₂O₃ NPs) have a wide range of applications in industry. The present study aims to reveal the time-dependent (24, 48, 72, 96 h) and dose-dependent (0, 5, 25, 50 mg/ml) effects of 13-nm-sized Al₂O₃ NPs on an agronomic plant wheat (Triticum aestivum L.) roots correlating with the appearance of various cellular stress responses. Al₂O₃ NPs reduced the root elongation by 40.2 % in 5 mg/ml, 50.6 % in 25 mg/ml, and 54.5 % in 50 mg/ml after 96 h. Histochemical analysis revealed lignin accumulation, callose deposition, and cellular damage in root cortex cells correlating the root elongation inhibition. Although the nanoparticle application decreased the total protein content with respect to control after 96 h, the peroxidase activity increased significantly which is considered to be one of the oxidative stress factors. Moreover, agarose gel results revealed that Al₂O₃ NPs induced DNA fragmentation being one of the important markers of programmed cell death. In conclusion, direct exposure to Al₂O₃ NPs leads to phytotoxicity significantly in wheat roots culminating in morphological, cellular, and molecular alterations.

Since the last century, humanity has sought ways to minimize the impact of the industrial growth in the environment. The textile industry, as one of the major contributors to water pollution, has been dumping coloured effluents which cause great impact in water bodies. The electrolytic process not only degrades the colour of the effluent but also transforms recalcitrant substances by direct or indirect oxidation. The ecotoxicological tests are used nowadays as a way to verify the toxicity degree of water bodies polluted by industrial and farming activities. The ecotoxicological tests consist in exposing determined organisms to the samples with the intention to evaluate their toxicity by observing the organisms’ responses. This study had the objective to degrade, by electrolytic process, a simulated textile effluent containing a mixture of Acid Blue 40 and Acid Red 151 dyes and the toxicity evaluation of the treated effluent by ecotoxicological tests. The bioassays used were tests with seeds of Lactuca sativa (lettuce), Eruca sativa (rocket), and Cucumis sativus (cucumber). Tests with the micro crustaceous Artemia salina and the yeast Saccharomyces cerevisiae were also conducted. The electrolytic treatment degraded the initial colour of the textile effluent, and the ecotoxicological tests indicated low toxicity to the treatment.

Groundwater samples collected from an unconfined shallow aquifer were analysed for major and trace element (TE) concentrations with the aim to investigate small-scale variations possibly linked to fertilizer residual products applied until 2004. The field site, located near Ferrara (Northern Italy), covers an area of 200 m²and was a former agricultural field then converted into a park and equipped with a grid of 13 monitoring wells. Three monitoring campaigns were carried out in June 2007, March and June 2009 in order to detect spatial and temporal variations in water quality. Groundwater nitrate, chloride, bromide and sulphate concentrations decreased with time indicating that the fertilizer plume was slowly replaced by unpolluted groundwater. However, the groundwater composition showed values of TEs (Fe, Mn, Al, As and Hg) above the recommended international and national guideline values. Dissolved TE concentrations varied randomly in the three campaigns, while TEs in the solid matrix did not show particular enrichment factors induced by fertilizer use. The data indicated that the dominant factor involved in determining small-scale spatial variability of TE concentrations in this shallow aquifer was the sediment-water interaction, while the temporal variation of TEs was driven by the organic matter leaching from the topsoil and by water table oscillations, which in turn drove the groundwater redox status. This study emphasizes the need of small-scale TE spatial resolution to discriminate between anthropogenic non-point sources of pollution (like fertilizers) and background concentrations.

In this paper, we compared the costs and benefits of reducing premature mortality caused by exposure to surface ozone and particulate matter with an aerodynamic diameter <2.5 μm (PM₂.₅) in East Asia in 2020. The cost of ozone and PM₂.₅emission reduction is estimated using the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS)-China model. The benefit of reducing premature mortality caused by exposure to corresponding ozone and PM₂.₅emission is valued by the value of statistical life (VSL). The costs and benefits are evaluated for two emission reduction policies in 2020 with varying stringency in China: Case FS (the strict policy implementation case in China) and Case FR (the less strict policy implementation case in China). For ozone, the emission reduction cost and the benefit of life saving are 33,000 and 8200, 36,600–99,700 and 22,200–60,700 (million int. $, 2005), for Case FS and Case FR, respectively. The corresponding cost and benefit for PM₂.₅are 3580 and 523, 292,000–797,000 and 194,000–530,000 (million int. $, 2005), respectively. In total (ozone and PM₂.₅), the respective values are 36,400 and 8720, 329,000–897,000 and 217,000–591,000 (million int. $, 2005). Owing to these large benefits and also relatively low PM control costs, the benefits of controlling PM₂.₅surpass control costs significantly. The benefit/cost ratio is especially high for PM₂.₅for both policies and highlight the priority of controlling aerosol emissions in East Asia.

A kind of volcanic tephra (VT) as abundant natural mineral in China was studied for phosphate (P) removal from rural micro-polluted wastewater. Physical and chemical properties of VT were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD), UV-visible diffuse reflectance spectrometry, and Fourier transform infrared spectroscopy (FT-IR). The uptake of P decreased with the increase of the initial solution pH, and the optimum solution pH required for maximum P removal rate was 2.0. Zeta potential analyses were carried out to vividly describe the surface charges at different solution pH. The equilibrium data were both fitted well for Langmuir and Freundlich isotherm models. Thermodynamic parameters including changes in standard enthalpy (ΔH⁰), standard entropy (ΔS⁰), and standard Gibbs free energy (ΔG⁰) were calculated. The removal of P was predominantly based on ion-exchange process when the initial solution pH in the range of 2.0–6.0. A given dose of VT can be recycled for eight times. VT minerals were attempted for P removal from rural micro-polluted wastewater collected in Shanghai, China containing 50 mg L⁻¹P, and the removal rate was determined to be nearly 100 % with the capacity of 0.5 mg P/g VT minerals. All our results indicated that VT could be a promising choice for P removal from micro-polluted wastewater in rural area with the distinct advantages of being low cost and environmentally benign.

Dairy soiled water (DSW) is water from concreted areas, hard stand areas and holding areas for livestock that has become contaminated by livestock faeces or urine, chemical fertilisers and parlour washings. Losses of DSW occur as point (e.g. storage, pivot irrigators) and diffuse losses (e.g. during or shortly after land application). The concept of a permeable reactive interceptor (PRI), comprising a denitrifying bioreactor woodchip cell to convert nitrate (NO₃⁻) to dinitrogen (N₂) gas and an adsorptive media cell for phosphorus (P) and ammonium (NH₄⁺) mitigation, attempts to simultaneously treat mixed pollutants. This study is the first attempt to test this concept at laboratory-scale. Washing of woodchip media prior to PRI operation produced low NO₃⁻but high NH₄⁺, dissolved reactive P (DRP) and dissolved organic carbon losses. Dairy soiled water was then treated in replicated PRIs containing woodchip in combination with zeolite or gravel compartments. In general, all PRIs were highly efficient at reducing NO₃⁻, NH₄⁺, DRP, dissolved unreactive phosphorus (DUP) and dissolved organic nitrogen (DON) from an influent water replicating DSW. Longitudinal and hydrochemical PRI profiles, as well as zeolite batch experiments, showed that woodchip can both enhance NO₃⁻reduction and adsorb nutrients. Since woodchip is likely to become saturated, it is important to place the reactive media cell further into the sequence of treatment. Even though the majority of the dissolved nutrients were mitigated, the PRIs also emitted greenhouse gases, which would need further remediation sequences.