Explore the vast range of titles available.

Apart from anthropogenic pollution, nitrate contamination is prevalent in practically all developing countries as a result of increased natural activities. The accumulation of nitrates in water bodies causes cumulative effects on living species, environmental receptors, and human vitality by accumulation along the food chain. Nitrates have recently piqued the interest of academics due to their widespread pollution of surface and groundwater systems. The presence of nitrate in high amounts in surface and groundwater causes a variety of health issues, including methemoglobinemia, diabetes, the emergence of infectious diseases, and a negative impact on aquatic organisms. Sensing nitrate is an alternative method for measuring the distribution of nitrate in various bodies of water. The nitrate-laden wastes from agricultural run-off, industrial discharges, and livestock and poultry farms contaminate resources. Nitrate toxicity shows swimming alteration, growth retardation, and eventually death among aquatic organisms. In fishes, it causes histopathological alteration of gills, esophagus, and brain. Therefore, this present review discusses the toxic concentration of nitrates, its adverse effects on the aquatic animals and the assessment of the safe limit of nitrate that is crucial to prevent chronic toxicity among invertebrates and fish.

On the 7 th of April, the Singaporean government enforced strict lockdown measures with the aim of reducing the transmission chain of the coronavirus disease 2019. This had a significant impact on the movement of people within the country. Our study aims to quantify the impact that these measures had on outdoor air pollution levels. We obtained air quality and weather data from April 2016 to May 2020, satellite data for 2019 and 2020 and mobility data for 2020 from Apple, Google, and the Singaporean Housing & Development Board. We determined that outdoor air pollution during the lockdown significantly decreased when compared with the same period in the previous four years even if we included corrections for long time trends in the analysis. The concentrations of the following pollutants PM 10 , PM 2.5 , NO 2 , CO, and SO 2 decreased by 23, 29, 54, 6, and 52%, respectively, whilst that of O 3 increased by 18%. The Pollutant Standard Index decreased by 19%. The trends of PM 2.5 and NO 2 were significantly correlated with mobility data. The NO 2 and SO 2 tropospheric concentrations and the total aerosol optical depth at 550 nm obtained from satellite data during the lockdown in 2020 were also lower than during the same period in 2019. Our results can be used to evaluate possible mitigation strategies for outdoor air quality in a longer term beyond this lockdown.

The main objective of this study is to examine the evolution and sensitivity of groundwater in the Ghiss-Nekor aquifer, looking at geology, hydrochemistry and water quality. The Ghiss-Nekor aquifer is located in the Rif region, where the geology is made up of limestone, marl and alluvial rocks. The impact of these rocks on groundwater recharge and circulation is significant, such as Mineralization. To achieve our objectives in this study, we began with determining the chemical composition of the groundwater through an in-depth analysis of hydrochemical parameters. The main ions analyzed are cations (Ca 2+ , Mg 2+ , Na + , K + ) and anions (HCO − 3 , SO 2− 4 , Cl − , NO − ) 3 . These analyzes enable us to determine the origin of the water and, through various statistical tests such as K-means, PCA, HAC, and Piper's facies diagram we obtain two facies' groups and two factors influencing the nature and quality of the groundwater, we can identify the origin and quality of the groundwater in this aquifer. The groundwater quality was evaluated in compliance with national and international standards. Test results highlighted significant differences in ion concentrations, particularly elevated levels concentration of chloride 828,16 mg/L and sulfate 814,101 mg/L, as well as certain pollutants like nitrate concentration 498,044 mg/L. There is also evidence of contamination from marine intrusion. The sources of pollutants include agricultural activities due to the excessive use of fertilizers and pesticides, industrial and domestic emissions, and the infiltration of untreated wastewater. These sources contribute to the degradation of groundwater quality. To protect the aquifer, various solutions have been proposed to combat pollution and preserve groundwater quality, including the implementation of sustainable agricultural practices and regular monitoring of water quality.

Studies on the consequences of urbanization often examine the effects of light, noise, and heat pollution independently on isolated species providing a limited understanding of how these combined stressors affect species interactions. Here, we investigate how these factors interact to affect parasitic frog-biting midges (Corethrella spp.) and their túngara frog (Engystomops pustulosus) hosts. A survey of túngara frog calling sites revealed that frog abundance was not significantly correlated with urbanization, light, noise, or temperature. In contrast, frog-biting midges were sensitive to light pollution and noise pollution. Increased light intensity significantly reduced midge abundance at low noise levels. At high noise intensity, there were no midges regardless of light level. Two field experiments controlling light and noise levels to examine attraction of the midges to their host and their feeding behavior confirmed the causality of these field patterns. These findings demonstrate that both light and noise pollution disrupt this host–parasite interaction and highlight the importance of considering interactions among species and types of pollutants to accurately assess the impacts of urbanization on ecological communities.

BackgroundBiomarkers have become a valuable tool in environmental assessment, since they contribute to predicting contaminants in monitoring programmes. This study aimed to investigate the toxicity of heavy metal pollution in Lake Qarun using a multibiomarker approach (morphological, oxidative stress, genotoxicity, stress proteins) in Solea aegyptiaca fish. During the winter and summer seasons, water and fish samples were collected from different locations along Lake Qarun; western and northern sectors were away from any source of pollution, while southern and eastern sectors were exposed to effluents discharged from El-Wadi and El-Bats drains, respectively. The environmental quality, as well as the accumulation of metals (Fe, Cu, Zn, Cd, Pb, Ni) in fish gills, liver, and muscles were assessed. Data were integrated using the integrated biomarker response index (IBRv2) for biomarker response interpretation.ResultsWater quality and bioaccumulation of heavy metals revealed a highly significant difference between samples collected from polluted sectors and those collected far from drainage water, and, seasonal differences were detected. Growth indices revealed a significant difference between sites and seasons. Fish from the western sector had the highest total antioxidant capacity in their gills, liver, and muscles, with no seasonal differences detected. However, the maximum value of malondialdehyde, protein carbonyl, 8-hydroxy-2′deoxyguanosine, metallothionein, heat shock protein 70, and DNA strand breaks in gills, liver, and muscles was detected in the polluting sectors. It revealed a significant difference between seasons, with the highest value during the winter season. According to IBRv2 results, the most effective biomarkers in this study were malondialdehyde and 8-hydroxy-2′deoxyguanosine in gills, protein carbonyl and metallothionein in the liver, heat shock protein 70 in gills and liver, and DNA strand break in gills, liver, and muscles.ConclusionsThis multibiomarker approach contributes to distinguishing between locations with varying levels of anthropogenic pollution, identifying the drainage water-exposed sectors as the most stressed and the winter season as the most critical time for Solea aegyptiaca owing to spawning. The biomarkers chosen are effective indicators in Solea aegyptiaca under stress, indicating the potential for environmental monitoring.

Abstract Antibiotic resistance genes (ARGs) are abundant in aquatic ecosystems affected by human activities. Understanding the fate of ARGs across different ecosystems is essential because of the significant role aquatic environments play in the cycle of antibiotic resistance. We quantified selected ARGs in Lake Maggiore, its main tributaries, and the effluent of the main wastewater treatment plant (WWTP) discharging directly into the lake. We linked their dynamics to the different anthropogenic impacts in each tributary's watershed. The dynamics of tetA in the lake were influenced by those of the rivers and the WWTP effluent, and by the concentration of N-NH4, related to anthropogenic pollution, while sul2 abundance in the lake was not influenced by any water inflow. The dynamics of the different ARGs varied across the different rivers. Rivers with watersheds characterized by high population density, touristic activities, and secondary industries released more ARGs, while ermB correlated with higher numbers of primary industries. This study suggests a limited contribution of treated wastewater in the spread of ARGs, indicating as prevalent origin other sources of pollution, calling for a reconsideration on what are considered the major sources of ARGs into the environment. Treated wastewaters can have a limited contribution to the spread of antimicrobial resistance genes in anthropogeneically impacted aquatic ecosystems.

The quantitative and qualitative stress on groundwater resources has been witnessed across the globe. The current study assesses the groundwater quality of Tirunelveli district which faces the hazard of groundwater contamination through seepage of toxins, considering the open dumping of huge volumes of solid waste. The findings from this study confirmed the presence of more than 20% samples in the \"poor to very poor\" quality with high concentrations of TDS, Cl , and NO , unfit for drinking, and other domestic purposes. The spatial distribution of TDS and NO highlighted the potential impact of solid waste dumping in the nearby landfill sites. K-means hierarchical clustering and multivariate analysis suggested that salinization and nitrate pollution was highly influenced by anthropogenic sources in comparison to geogenic sources. Rock water interaction and evaporation processes emerged as the two major dominant natural mechanisms controlling the groundwater chemistry. Four hydro-chemical facies were identified in the order of Ca-HCO  > Ca-Mg-Cl > Na-Cl > mixed Ca-Na-HCO . Thus, this study creates an urgent need of mitigation measures towards curbing and management of solid waste disposal and hence, the potential hazard of contaminant seepage into the groundwater.