In the present study, the endocrine activity of the antiepileptic pharmaceutical carbamazepine (CBZ) in the crustacean Daphnia magna was assessed. To assess the hormonal activity of the drug, we exposed maternal daphnids and embryos to environmental relevant concentrations of CBZ (ranging from 10 to 200 μg/L) and to mixtures of CBZ with fenoxycarb (FEN; 1 μg/L). Chronic exposure to CBZ significantly decreased the reproductive output and the number of molts of D. magna at 200 μg/L. This compound induced the production of male offspring (12 ± 1.7 %), in a non-concentration-dependent manner, acting as a weak juvenile hormone analog. Results showed that this substance, at tested concentrations, did not antagonize the juvenoid action of FEN. Further, CBZ has shown to be toxic to daphnid embryos through maternal exposure interfering with their normal gastrulation and organogenesis stages but not producing direct embryo toxicity. These findings suggest that CBZ could act as an endocrine disruptor in D. magna as it decreases the reproductive output, interferes with sex determination, and causes development abnormality in offspring. Therefore, CBZ could directly affect the population sustainability.

Geothermal energy is known to be a clean and renewable energy resource. However, geothermal fluid has significant impacts on surface water quality when disposed in an uncontrolled manner due to the high concentrations of numerous dissolved constituents and the elevated thermal content. The geothermal fluid in western Anatolia typically contains high concentrations of arsenic, boron, and lithium that are toxic to human and plant life. A river system in western Anatolia, Turkey, receives uncontrolled waste geothermal fluid discharge from three fields and is thermally and chemically contaminated. A one-dimensional water quality model is developed to assess the extent and strength of geothermal pollution in the river system. The calibrated and verified model results revealed that although both the point and nonpoint sources of contamination are influential in the water quality degradation, point discharges of waste geothermal fluid were responsible for dramatic increases in the contaminant concentrations and water temperature in the river. The model was later used to analyze the potential measures to improve the degraded water quality and compare the effectiveness of structural and non-structural mitigation scenarios.

The drastic desiccation of the Aral Sea has led to severe desertification of the former lake areas. Dust storms occur frequently, causing regional environmental degradation of the Aral basin and a serious ecological disaster. Knowledge of the temporal variability in dust emissions and the potential diffusion characteristics of dust aerosol originating from the Aral Sea basin in recent years are, however, lacking. To address this knowledge gap, we studied the interannual and intraannual changes in dust aerosol from the Aral Sea basin and its potentially seasonal diffusion characteristics from 2005 to 2013 using Ozone Monitoring Instrument (OMI) aerosol data (2005–2013) and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Results show that the OMI aerosol index (AI) annual mean, standard deviation, median, and maximum values exhibit a strong increasing trend because of the continuous decrease in the water level since 2005. The annually mean OMI AI increases to 1.47 by 2013. Peak AI values are recorded in spring (March–May) and early winter (November–January of the following year), indicating notifying seasonal differences. The potential distance and height of air parcel trajectories to the northeast are greater than those to the west and south, whereas the air parcel trajectory proportion of the former is lower than that of the latter. The potential transport distance of dust aerosol to the northeast is greatest in spring and winter. This transport distance is less in autumn, with the minimum observed in summer. Dust transport distance to the west and south in different seasons is not significantly different. The present results may help in further understanding the emission, long-range transport, and deposition of dust from the dry lake bed of the Aral Sea as well as providing a motivation for the sensible use and protection of these tail-end lakes.

Ecological ditches have demonstrated the ability to filter and control nutrient transport to rivers. Few studies, however, have examined the internal loading of nitrogen (N) and phosphorus (P) in these systems due to vegetation decomposition. Most often, this concept is overlooked during evaluation of the nutrient removal rate of the ditches. Thus, the litter bag technique was used to analyze nutrient release to surface water during these processes. Mesocosm and field experiments were conducted to assess the growth characteristics and consequent nutrient accumulation by six ditch plant species. Of the six, Canna indica had the highest aboveground accumulation of N and P. About 85–95 % increase in the aboveground biomass was recorded at the end of the experimental period. The removal efficiencies of TN, TP, and NH₄-N from the sewage reached up to 72–99.4, 64–98.7, and 75 %–100, respectively. Complete removal of all NO₃-N was achieved. The amounts of N and P uptake by plant species were closely related to the biomass of plants. During the decaying process, N and P concentrations in the aboveground biomass decreased. These lost nutrients were eventually shifted to the system, which led to a deterioration of the water quality. Therefore, harvesting of aboveground biomass from inside the ditch is an appropriate intervention to prevent the release of N and P in the dormant season. The finding is important for planning an efficient eco-ditch system and predicting the influence of nutrient loading in the eco-ditches upon senescence of ditch plants.

Seven full-scale wastewater treatment plants were investigated to highlight the effectiveness of each treatment stage on removing Escherichia coli. The primary sedimentation achieved an average E. coli removal efficiency of 30.5% which was much lower than the suspended solids (58%), thus, revealing the absence of a linear relationship between the two parameters. Biological processes proved to be very important in the removal of E. coli through adsorption inside the sludge flocs and complex decay (mortality). In biological processes with a long retention time, such as activated sludge denitrification-nitrification, the decay was very important, whereas in the more traditional activated sludge process, without nitrification, the contribution of adsorption and mortality was quite balanced. Overall, the mechanical-biological treatment achieved a removal efficiency of 91.8–96.5% depending on the process. Additional removal can be achieved by disinfection. The effectiveness of E. coli removal with sodium hypochlorite was strictly depended on the product of residual chlorine (C R) with the contact time (t). The experimental curve fitted the Collins model well, with a standard deviation of less than 7%.

This research investigated the efficiency of South African sands and a type of zero-valent iron (ZVI) to remove nitrate from contaminated water. Batch experiments were carried out using soils widely available in the region of Kwazulu-Natal in South Africa (Berea red Sand (BRS) and Umgeni Sand (US), a type of ZVI and two mixes of BRS-ZVI (75–25 and 50–50 % w/w). The experiments were conducted in semi-anoxic conditions to investigate the nitrate removal potentials of the substrates. Batch tests revealed 100 % of nitrate removal by ZVI at lower concentrations (10–25 mg/L), while at higher concentrations (up to 100 mg/L), the removal efficiency decreased. The BRS, as sole material, showed the highest removal (70 %) at 25-mg/L nitrate solution, while at higher concentrations (50 and 100 mg/L), the nitrate removal was 36.7 and 42.9 %, respectively. The ZVI-BRS 50 % mix showed the best performance in terms of both rates and percentage of removal for most of the nitrate concentrations investigated indicating that a higher amount of BRS in the mixes improves the adsorption capacity. Both Langmuir and Freundlich isotherm models were applied to experimental data, and Langmuir described better the nitrate removal process. According with our findings, the BRS could represent a viable alternative to the ZVI to reduce the cost of the treatment and to increase the nitrate removal capacity.

Triclosan (TCS) is an antimicrobial agent that is extensively used in personal care products (PCPs), and its residue is frequently reported in aquatic environments. In this study, we investigated the reaction behavior of TCS during enzyme-catalyzed oxidative coupling reactions (ECOCRs) by laccase from Pleurotus ostreatus and determined how the presence of natural organic matter (NOM) influenced the formation of the products. Results indicated that the optimum pH for TCS transformation was 6.0 in laccase-mediated ECOCRs. At pH values below 5.0 and above 7.0, the pseudo first-order kinetic rate constants (k) of TCS transformation declined significantly. Moreover, the k values of TCS transformation increased as the laccase activity increased (0.1179–0.5757 h⁻¹). A total of four product peaks were generated, and they were more hydrophobic than TCS. High-resolution mass spectrometry (HRMS) analysis indicated that these products could be the oligomers resulting from TCS self-coupling reactions. The relative peak areas of these oligomers displayed strong linear correlations with the different initial TCS concentrations, and the saturation point of laccase (3.0 U mL⁻¹), when the binding with TCS was 40 μmol L⁻¹. In the presence of NOM (i.e., humates and fulvates), humates in particular strongly inhibited TCS transformation and lowered the extent of its self-coupling, which likely resulted from the cross-coupling between TCS and NOM. Our study improves a better understanding of the reaction behavior of TCS in the natural aquatic environment during laccase-mediated ECOCRs.

An in situ post tsunami study was conducted to assess the effect of water management and rainfalls in soil properties and water quality at a low-lying coastal area of central Chile affected by Mw8.8 Earthquake Tsunami the night of 27 February 2010. Soil samples were taken at two depths (0 to 20 and 20 to 40 cm) during 2010 and late 2012. Water quality in a local shallow well was also monitored in 2010 and 2012. High soil salinity was recorded 2 months later than tsunami occurs, closely associated to water-soluble chloride and cations (Cl⁻ > > Na⁺ > > Ca²⁺ > Mg²⁺ > K⁺), ionic toxicities, and vegetal inhibition (Vasconcellea pubescens) by less available water to plants. An initial reduction in soil pH due to ionic strength and coarse-textured class of soil was observed and the sodium adsorption ratio (SAR) in soil varied between 5.7 and 11.2 (mmol L⁻¹)⁰.⁵ showing to be saline. Although SARw values are very high (>18 (mmol L⁻¹)⁰.⁵), it does not exist risks of reduction on soil infiltration rates according to ECw (>5 dS m⁻¹) obtained. After 2 years, soil salinity was drastically reduced in the affected areas due to high soil permeability and natural attenuation (rainfalls and leaching effects), with sulfate and bicarbonate concentrations showing excessive values. Further, irrigation water quality returned to pre-tsunami situation, with only levels of sodium slightly exceeding desirable range from health point of view. Finally, it is suggested a proper design of irrigation systems before implementing other management practices.

In this study, the genotoxic and histopathological effects of olive-mill wastewater (OMW) on the tissue cells of Lepomis gibbosus were investigated. The fish were caught from Topçam dam lake (Çine/Aydın) and were exposed to the wastewater in 50-L aquariums which contained 0.5 % OMW for 3–5 and 7 days. In genotoxic investigations, a statistically significant increase was observed in the frequency of micronuclei in the L. gibbosus in experimental groups. As a result of the exposure to OMW, histopathological findings which showed a parallel increase with the amount of exposure in the gill, liver and muscle tissues were determined. In the gills, disruption of lamellae shape, shortening and breakage of primary and secondary lamellae, fusion and branching, separation in the secondary lamellae epithelium, ballooning dilation, hyperplasia in support cells and increase in mucus cells were observed. In the parenchyma of the liver, a difference in local staining, focal necrosis, haemorrhaging in necrotic areas, oedema of blood vessels, expansion in sinusoids, congestion and dilation in portal veins, deterioration of vessel walls, cytoplasmic vacuolization in hepatocytes, pyknotic nuclei, decrease in glycogen storage in hepatocytes near the central vein and aggregates of melanomacrophages were also observed. The necrosis in muscle bundles, widespread oedema between myofibrils, degeneration and separation in some muscle groups, decrease in glycogen content, intramuscular oedema and atrophy in the myofibers were determined in the experimental groups.

A hazard assessment was conducted of contaminants found at inflow and outflow monitoring stations of the Water Conservation Areas (WCAs) in South Florida. WCAs (1, 2A, 2B 3A, 3B) lie north of Everglades National Park (ENP) and southeast of Lake Okeechobee, span almost 1400 mi², and serve a number of water resource functions which include food control for three major counties, delivering water to ENP, and water storage during dry downs and for recharging groundwater. Measured concentrations of contaminants in sediment and water were evaluated at 13 monitoring stations in the WCAs using a screening benchmark approach. Chemicals of potential ecological concern (COPECs) included herbicides, organochlorine pesticides, organochlorine industrial chemicals, and heavy metals. Of the stations, total cadmium was a COPEC at nine of them. Most sites had maximum detected concentrations of cadmium that exceeded state of Florida (USA) water quality criteria standards. Beryllium, copper, mercury, methylmercury, and zinc (measured as total metal concentration) also exceeded surface water criteria at several sites. Several organochlorine chemicals in sediment were COPECs; chlordane, polychlorinated biphenyls, and p,p′-DDT with its metabolites (p,p′-DDD and p,p′-DDE) had more than 200 sediment benchmark exceedences. Mercury in fish tissue was a COPEC at S5A when compared to a no-effect residue value for survival. Greater potential hazards were observed at northern monitoring sites than southern sites around the WCAs. The hazard assessment approach for screening water quality data described in this article can help focus higher tier risk assessment work, including laboratory, field, and data analysis studies, on contaminants with greater potential for adverse biological effects.