Clean-soil Air Water最新文献

In Unare and Píritu Coastal Lagoons, a study was carried out to assess the effect of C, N, and P load contributions on the capability of the sediments to immobilize phosphates. To achieve the later, the geochemical data of the sediments were coupled to the P-sorption index of Bache and Williams (IBW). In both lagoons, the sediments showed a pH > 7 because of calcareous sedimentation. The inorganic carbon values in the lagoons displayed a spatial distribution with higher concentrations toward the shores, that is defined by the carbonate lithology. On the contrary, the inner part of the lagoons was characterized by the presence of organic materials associated to the clay. The phosphorus content in the Unare Lagoon ranged from 290 to 625 mg kg⁻¹, whereas in the Píritu Lagoon the values fluctuated between 213 and 1013 mg kg⁻¹. The highest concentrations of phosphorus in both lagoons could be linked to sewage and runoff input from agricultural and livestock activities around the lagoon systems. The IBW displayed adsorption average values of 21.97 and 27.42 for Unare and Píritu Lagoon, respectively, corresponding to a rather low P sorption. In Unare Lagoon, the IBW showed positive correlations with C, N and Fe_labile but negative with P. However, in the Píritu Lagoon, despite the analogous lithology of the lagoons, a slightly positive non-significative correlation between IBW and IC was only found. Although the sediments adsorb P with a rather low capacity, they can mitigate the eutrophication process in the studied lagoons.

The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater and its potential as an airborne transmission source require extensive investigation, particularly in wastewater treatment plants (WWTPs), where few studies have been conducted. The aim of this study was to investigate the presence of SARS-CoV-2 and norovirus (NoV) RNA in wastewater and air samples collected from a municipal WWTP. In addition, the study assessed the potential risk of viral exposure among WWTP employees. In both the summer and winter campaigns of this study, SARS-CoV-2 and NoV RNA were quantified in wastewater/sludge samples other than effluent. Viral RNA was not detected in any of the air samples collected. The exposure risk assessment with the SARS-CoV-2 RNA concentrations in the influent pumping station of this study shows a lower risk than the calculation with the historical data provided by AquaVall, but both show a low-to-medium exposure risk for the WWTP workers. The sensitivity analysis shows that the result of the model is strongly influenced by the SARS-CoV-2 RNA quantification in the wastewater. This study underscores the need for extensive investigations into the presence and viability of SARS-CoV-2 in wastewater, especially as a potential airborne transmission source within WWTPs.

This study investigates the potential health risks associated with ion concentrations in fountains used for drinking water in the Antalya/Konyaaltı tourism center region. A total of 32 fountain samples commonly used during the summer were analyzed to determine the anion and cation concentrations using ion chromatography equipped with a conductivity detector. The results showed high accuracy and reliability, with R² values ranging between 0.998 and 0.999 and recovery values between 97% and 110% at low and high concentrations. The method detection limit and method quantification limit were determined as 0.004 and 0.276, respectively, whereas the pH values ranged from 6.71 to 7.69. When examining the average fluoride and nitrate levels in different age groups, the nitrate daily acceptable intake (total hardness index) values were found to be 0.175, 0.091, and 0.076 µg kg⁻¹ body weight per day for children, adolescents, and adults, respectively. Overall, the study suggests that children have the highest exposure levels due to their lower body weight, and exposure levels decrease with increasing age.

Above-permissible levels of arsenic (As) in irrigation water lead to toxic levels in wheat grains, increasing health risks for humans. In this study, two zinc (Zn)-biofortified wheat (Triticum aestivum L.) cultivars (Akbar-2019 and Zincol-2016) were grown in pots with two Zn application rates (0 and 8 mg Zn kg⁻¹) and three levels of As in irrigation water (distilled-water control, 100 and 1000 µg As L⁻¹). Irrigation with As-contaminated water decreased dry matter yields, concentrations of grain phosphorus (P) and Zn, and estimated daily intake (EDI) of Zn. Conversely, it increased grain As concentration and As EDI. Soil Zn application mitigated the negative effects of As on dry matter yields of both cultivars while simultaneously enhancing grain Zn concentration and Zn EDI. On average, Zn application increased grain Zn concentration by 114% compared to no Zn application. Additionally, Zn application decreased grain As concentration at all As levels. In conclusion, this study suggests that applying Zn to Zn-biofortified wheat irrigated with As-contaminated water can mitigate the toxic effects of As on wheat. It increase Zn concentration and decrease As concentration in wheat grains, which is vital for enhancing grain quality for human consumption.

River ecosystems in Central Asia face significant stress from environmental changes and pollution. This study assesses temporal and spatial variations in water quality parameters within the Zarafshan River Basin using retrospective data and field measurements. Water quality indicators, including electrical conductivity (EC), total suspended solids (TSS), ammonium nitrogen (N-NH₄), nitrite nitrogen (N-NO₂), nitrate nitrogen (N-NO₃), temperature (T), chemical oxygen demand (COD), dissolved oxygen (DO), and discharge, were analyzed using the Pearson's correlation coefficient and ANOVA, with the Mann–Kendall (MK) test detecting trends over time. Obtained results indicate significant seasonal effects with elevated TSS during summer, increasing sediment load and changing aquatic habitats. The strong inverse correlation (–0.89) between DO and N-NH₄ signifies ecological challenges particularly in low DO concentrations during summer (3.25 mg L^–1). Long-term analysis identifies Navoiazot chemical factory as a major pollution hotspot. Spatial analyses based on extended sampling have revealed the Siab and Dargom canals and Samarkand City as major pollution sources of elevated N-NO₂ and COD, respectively. Trends at various gauging stations (MK-test) show increasing EC (τ = 0.72) and N-NH₄ (τ = 0.46) levels, with decreasing TSS, N-NO₃, T, and COD levels over time. Recommendations include targeted measures to reduce pollution at the Navoiazot factory and downstream, introducing sustainable agriculture practices, increasing public awareness for environmental conservation, and improving urban wastewater treatment to meet water quality requirements for different users.

The prevalence of nitrates (NO₃⁻) in groundwater due to the extensive application of fertilizers and anthropogenic sources pollutes the groundwater. Machine learning (ML) techniques are now being increasingly deployed to achieve high precision in predicting water quality. This study assesses the efficacy of nine distinct ML algorithms, namely, linear regression, polynomial regression, decision tree, random forest (RF), support vector machine, multilayer perceptron regressor, eXtreme gradient boosting (XGB), light gradient boosting (LGB), and K-nearest neighbors to predict nitrate concentration in the groundwater in Thiruvannamalai District, Tamil Nadu. Overall, 360 water samples for 1 year and 14 groundwater variables were determined to predict nitrate. Performance evaluation metrics such as root mean square error (RMSE), moving average error (MAE), and correlation coefficient (R²) were evaluated for pre-monsoon, monsoon, and post-monsoon seasons. For all three seasons, RF predicted the nitrate concentration with low values of RMSE, MAE, and higher values of R². The results show values for RF with: RSME: 0.49, MAE: 1.30, and R²: 0.94, which has a higher prediction tailed by LGB and XGB and is true for all the seasons. The results from the study will aid the policymakers in planning the strategy for remediation.

This study aims to examine the nitrogen removal characteristics and microbial community variation at low hydraulic retention time (HRT) in a shallow constructed wetland (SCW) using iron–carbon (Fe–C) porous filter material (PFM) as substrate. Effects of influent nitrogen forms and chemical oxygen demand (COD)/N ratio on nitrogen removal performance at HRT of 1 day were investigated. Results showed that total nitrogen (TN) removal declined with the decrease of influent NH₄⁺-N-to-NO₃⁻-N ratio. When the influent NH₄⁺-N/NO₃⁻-N ratio was 0.1, TN removal decreased by 15.4% compared with that at ratio of 2.0. The increase of influent COD/N ratio enhanced NO₃⁻-N reduction, and TN removal reached 74.5% at influent COD/N ratio 7.0. The microbial community was analyzed for the biofilm samples on Fe–C PFM at front (WF), middle (WM), and back (WB) of SCW. Proteobacteria, Bacteroidetes, Chloroflexi, and Firmicutes were dominant bacteria phyla. The relative abundance of genera involved in the nitrification and denitrification decreased with the influent flow. The iron autotrophic denitrifying and macromolecular organics degrading bacteria were abundant in the middle and back of SCW. Microbial nitrification and denitrification, plant uptake, and plant synergism contributed to 86.3%, 7.41%, and 19.9% of N removal, respectively. These results demonstrated that the SCW with Fe–C PFM as substrate was efficient in nitrogen removal at low HRT.

The former Lepanto landfill in the Santiago Metropolitan Region in Central Chile ceased operations in 2002 after 24 years. Currently, a biogas recovery center operates on this site. The objective of this pilot study was to evaluate the atmospheric concentrations of two polycyclic aromatic hydrocarbons (PAHs, i.e., phenanthrene and fluoranthene) at three points downwind from the former Lepanto landfill using passive air samplers and polyurethane foam disks to provide 3-month average concentrations of contaminants during winter months. The results showed concentrations ranging between 2 and 65 ng m⁻³ and decreasing with distance from the former landfill. Given that the distance to other potential sources was similar in all sampling sites, the evidence found suggested that the former Lepanto landfill may contribute to the local PAH inventory. Thus, we suggest that former landfills are potential candidates for long-term monitoring as they can represent a less-known environmental liability for residents. Additionally, we provide insights on how the Chilean environmental protection system can establish reclamation steps for their management after closure.