Search Results (392)

Heavy metal pollution from human activities is an increasing environmental concern. This study investigates the concentrations of Cu, Pb, Zn, Cd, Hg, and As in the coastal seawater offshore of Beihai, Guangxi, in April 2021, and explores their relationships with dissolved inorganic nitrogen, phosphate, and salinity. Our results reveal higher heavy metal concentrations in the northern nearshore waters and lower levels in southern offshore areas, with surface waters generally exhibiting greater enrichment than bottom waters. Surface concentrations show a decreasing trend from the northeast to the southwest, likely influenced by prevailing northeast monsoon winds. While bottom water concentrations decline from the northwest to the southeast, which indicates the influence of riverine runoff, particularly from the Qinzhou Bay estuary. Heavy metal levels in southern Beihai waters are comparable to those in the Beibu Gulf, except for Hg and Zn, which are significantly higher in the water of the Beibu Gulf. Notably, heavy metal concentrations in both Beihai and Beibu Gulf remain considerably lower than those observed in the coastal waters of Guangdong. Overall, Beihai’s coastal seawater meets China’s Class I quality standards. Nonetheless, continued monitoring is essential, especially of the potential ecological impacts of Hg and Zn on marine life. Full article

Conventional tillage and monocropping are common practices employed for cotton production in the Southern Great Plains (SGP) region, but they can be detrimental to soil health, crop yield, and water resources when improperly managed. Regenerative practices such as cover crops and conservation tillage have been suggested as an alternative. The proposed shift in management practices originates from the need to make agriculture resilient to extreme weather events including intense rainfall and drought. The objective of this study is to test the effects of these regenerative practices in an environment with limited rainfall. Runoff volume, nutrient and sediment concentrations and loadings, and surface soil moisture levels were compared on twelve half-acre (0.2 hectare) cotton plots that employed different cotton seeding rates and variable winter wheat cover crop presence. A winter cover implemented on plots with a high cotton seeding rate significantly reduced runoff when compared to other treatments (p = 0.032). Cover cropped treatments did not show significant effects on nutrient or sediment loadings, although slight reductions were observed in the concentrations and loadings of total Kjeldahl nitrogen, total phosphorus, total solids, and Escherichia coli. The limitations of this study included a short timeframe, mechanical failures, and drought. These factors potentially reduced the statistical differences in several findings. More efficient methods of crop production must continue to be developed for agriculture in the SGP to conserve soil and water resources, improve soil health and crop yields, and enhance resiliency to climate change. Full article

This study aimed to evaluate the agronomic performance and environmental impact of controlled-release coated fertilizers (CRCFs) in upland maize systems. Specifically, we sought to determine the optimal nitrogen (N) application rate that maximizes nitrogen use efficiency (NUE) and minimizes nutrient runoff, while maintaining yield comparable to conventional fertilization practices. A two-year field experiment (2017–2018) was conducted to assess CRCF formulations composed of urea, MAP, and potassium sulfate encapsulated in LDPE/EVA coatings with talc, humic acid, and starch additives. Treatments included various nitrogen application rates (33–90 kg N ha⁻¹) using CRCF and a conventional NPK fertilizer (150 kg N ha⁻¹). Measurements included fresh ear yield, aboveground biomass, NUE, and concentrations of total N (TN), nitrate N (NO₃⁻–N), and total P (TP) in surface runoff. Statistical analyses were performed using linear and quadratic regression models to determine yield responses and agronomic optimal N rate. CRCF treatments produced yields comparable to or exceeding those of conventional fertilization while using less than half the recommended N input. The modeled agronomic optimum N rate was 88.4 kg N ha⁻¹, which closely matched the maximum observed yield. CRCF application significantly reduced TN, NO₃⁻–N, and TP runoff in 2017 and improved NUE up to 71.2%. Subsurface placement and sigmoidal nutrient release contributed to reduced nutrient losses. CRCFs can maintain maize yield while reducing N input by approximately 40%, aligning with climate-smart agriculture principles. This strategy enhances NUE, reduces environmental risks, and offers economic benefits by enabling single basal application. Further multi-site studies are recommended to validate these findings under diverse agroecological conditions. Full article

The pollution of water bodies has deteriorated the quality of freshwater and the health of the natural ecosystem. In the present study, the water quality index (WQI) was used to evaluate the spatial and temporal contamination levels in Lake Yuriria, Guanajuato, Mexico. Water quality was monitored at 27 different locations (monitoring points) in the dry season (April) and after the rainy season (November), measuring 21 physicochemical water parameters, 2 biological parameters, and 19 metal concentrations. The data analysis revealed that Yuriria Lake is a eutrophic water body. Six monitoring points exhibited a poor WQI (25–50) in April, and seven monitoring sites were classified as having poor water quality in November. The remaining monitoring points showed a WQI categorized as fair (51–70) in both periods. The present study analyzes an extensive distribution of monitoring points over the lake’s surface in two periods, showing a significant spatial and temporal representation of water quality. In addition, the major pollution sources identified include agricultural runoff and effluents from a nearby waterway and freshwater river. Finally, the key physicochemical parameters that determined the water quality were identified. BOD₅, NH₄⁺, P, orthophosphates, DO, conductivity, TSS, and color were linked to anthropogenic pollution sources, and Li, Ni, Zn, Cd, Ba, and Pb concentrations were linked to natural contamination sources. This study demonstrates the utility and versatility of these methodologies in water quality research, and it is the first spatial and temporal WQI analysis of Yuriria Lake. Full article

To clarify the current state of heavy metal contamination in the sediments of lakes in China, the data on six heavy metals derived from the sediment samples of 71 lakes across China from 2003 to 2022 are collected in this study through meta-analysis. Uncertainty analysis is conducted using the Monte Carlo method to evaluate the heavy metals against cumulative characteristics, potential ecological risk, and toxicity indicators. The following conclusions are reached. (1) There is severe pollution in lake sediments in China. The concentrations of Cu, Pb, Zn, Ni, and Cd in lakes exceed their corresponding soil background values. Cr heavy metal contamination exceeded the soil background values in 54.5% of lakes. (2) Cd is the major pollutant in lake sediments across China, followed by Cu, Zn, Pb, Ni, and Cr in descending order. Lakes with higher ecological risk are predominantly concentrated in quadrants 2 and 3, indicating an overall high ecological risk status for Chinese lakes and significant potential ecological hazards. Pb and Cr are identified as the most toxic elements in lake sediments, with the lakes of higher toxicity mainly concentrated in quadrants 3 and 4. (3) Heavy metal pollution shows a significant trend of variation by region. The sources of heavy metals in lake sediments differ between the southern, central, and northern regions of China. In the lakes located in northern China, pollution is largely attributed to mining and industrial emissions, with agriculture as a less significant factor. In the central region, surface runoff and domestic sewage are the main contributors, while industrial and agricultural emissions play a minor role. In the south, industrial emission is the major source of pollution, with agricultural emission and natural factors being less significant. Full article

This investigation examined the physicochemical characteristics and heavy metal contamination within the surface sediments and aquatic environments of Pattani Bay, Thailand, throughout both wet and dry seasons. The sediments were primarily composed of fine-grained materials, specifically silt and clay, and exhibited greater propensity to absorb heavy metals from water. Notably elevated concentrations of Cd and Pb were detected, particularly within riverine sediment deposits. This indicates that riverine inputs are significant pathways of the contamination and potentially associated with historical mining activities. Seasonal fluctuations affected physicochemical parameters as well as metal concentrations. The heightened levels of Cd and Pb during the wet season were attributed to runoff phenomena. Pollution indices including the Contamination Factor (CF), pollution load index (PLI), and geoaccumulation index (Igeo) demonstrated moderate to extremely high contamination levels of Cd and Pb in certain areas. The Principal Component Analysis (PCA) suggested possible similar sources for multiple metals including Cd, Cu, Pb, and Zn. The results showed that the heavy metal pollution present is serious, especially for Cd and Pb. These could lead to high ecological health risks and so it is necessary to focus on implementing environmental management strategies for Pattani Bay. Full article

Climate change and anthropogenic alterations in biogeochemical cycles are intensifying the frequency, duration, and potential toxicity of harmful algal blooms (HABs) in marine ecosystems. However, these effects are highly variable and depend on species identity, strain-specific traits, and local environmental conditions. Key drivers include rising sea surface temperatures, changes in salinity resulting from altered precipitation patterns and runoff, and elevated CO₂ levels leading to ocean acidification. Heterosigma akashiwo, a euryhaline raphidophyte responsible for the widespread killing of fish, is particularly responsive to these changes. This study investigated the combined effects of temperature, salinity, and CO₂ concentration on the growth, yield, and cell membrane permeability of H. akashiwo using a Design of Experiment (DOE) approach. DOE facilitates a detailed and systematic analysis of multifactorial interactions, enabling a deeper understanding of complex relationships while maximizing efficiency and minimizing the use of experimental resources. The results revealed that growth and yield were maximized at higher temperatures and salinities, whereas cell permeability increased under cooler, less saline, and lower CO₂ conditions. These findings suggest that projected future ocean conditions may enhance biomass production while potentially reducing cellular permeability and, by extension, toxicity. This study highlights the value of the DOE framework in identifying key interactions among environmental drivers of HABs, offering a practical foundation for future predictive modeling under climate change scenarios. Full article

Pharmaceuticals and microplastics are persistent emerging contaminants that pose significant risks to aquatic ecosystems and ecological health. Although extensively reviewed individually, a comprehensive, integrated assessment of their environmental pathways, bioaccumulation dynamics, and toxicological impacts remains limited. This review synthesizes current research on the environmental fate and impact of pharmaceuticals and microplastics, emphasizing their combined influence on aquatic organisms and ecosystems. This review provides a thorough and comprehensive examination of their predominant pathways, sources, and distribution, highlighting wastewater disposal, agricultural runoff, and atmospheric deposition. Studies indicate that pharmaceuticals, such as antibiotics and painkillers, are detected in concentrations ranging from ng/L to μg/L in surface waters, while MPs are found in densities up to 106 particles/m³ in some marine and freshwater systems. The toxicological effects of these pollutants on aquatic organisms, particularly fish, are discussed, with emphasis on bioaccumulation and biomagnification in the food chain, physiological effects including effects on growth, reproduction, immune system performance, and behavioral changes. The ecological consequences, including disruptions to trophic dynamics and ecosystem stability, are also addressed. Although valuable efforts, mitigation and remediation strategies remain inadequate, and further research is needed because they do not capture the scale and complexity of these hazards. This review highlights the urgent need to advance treatment technologies, establish comprehensive regulatory frameworks, and organize intensive research on long-term ecological impacts to address the environmental threats posed by pharmaceuticals and microplastics. Full article

Extreme precipitation events are one of the common hazards in eastern Texas, generating a large amount of storm water. Water running off urban areas may carry non-point source (NPS) pollution to natural resources such as rivers and lakes. Urbanization exacerbates this issue by increasing impervious surfaces that prevent natural infiltration. This study evaluated the efficacy of rain gardens, a nature-based best management practice (BMP), in mitigating NPS pollution from urban stormwater runoff. Stormwater samples were collected at inflow and outflow points of three rain gardens and analyzed for various water quality parameters, including pH, electrical conductivity, fluoride, chloride, nitrate, nitrite, phosphate, sulfate, salts, carbonates, bicarbonates, sodium, potassium, aluminum, boron, calcium, mercury, arsenic, copper iron lead magnesium, manganese and zinc. Removal efficiencies for nitrate, phosphate, and zinc exceeded 70%, while heavy metals such as lead achieved reductions up to 80%. However, certain parameters, such as calcium, magnesium and conductivity, showed increased outflow concentrations, attributed to substrate leaching. These increases resulted in a higher outflow pH. Overall, the pollutants were removed with an efficiency exceeding 50%. These findings demonstrate that rain gardens are an effective and sustainable solution for managing urban stormwater runoff and mitigating NPS pollution in eastern Texas, particularly in regions vulnerable to extreme precipitation events. Full article

Nitrate (NO₃⁻) pollution resulting from anthropogenic activities represents one of the most prevalent environmental issues in karst spring catchments of northern China. In June 2021, a comprehensive study was conducted in the Jinan Spring Catchment (JSC), where 30 groundwater and surface water samples were collected. The sources and spatial distribution of nitrate pollution were systematically investigated through hydrochemical analysis combined with dual-isotope tracing techniques (δ¹⁵N_NO3 and δ¹⁸O_NO3). Analytical results revealed that the predominant anion and cation sequences were HCO₃⁻ > SO₄²⁻ > Cl⁻ > NO₃⁻ and Ca²⁺ > Na⁺ > Mg²⁺ > K⁺, respectively, with HCO₃·SO₄-Ca identified as the primary hydrochemical type. Notably, the average NO₃⁻ concentration in groundwater (46.62 mg/L) significantly exceeded that in surface water (4.96 mg/L). Among the water samples, 11 locations exhibited substantial nitrate pollution, demonstrating an exceedance rate of 42%. Particularly, the NO₃⁻-N concentrations in both the upstream recharge area and downstream drainage area were markedly higher than those in the runoff area. The spatial distribution of NO₃⁻ concentrations was primarily influenced by mixing processes, with no significant evidence of denitrification observed. The isotopic compositions ranged from −1.42‰ to 12.79‰ for δ¹⁵N_NO3 and 0.50‰ to 15.63‰ for δ¹⁸O_NO3. Bayesian isotope mixing model (MixSIAR) analysis indicated that domestic sewage and manure constituted the principal nitrate sources, contributing 37.1% and 56.9% to groundwater and surface water, respectively. Secondary sources included soil organic nitrogen, rainfall and fertilizer NH₄⁺, and chemical fertilizers, while atmospheric deposition showed the lowest contribution rate. Additionally, potential mixing of soil organic nitrogen with chemical fertilizer was identified. Full article

This study evaluated the allocation of residential detention tanks in the Alto da Boa Vista Condominium, Federal District, Brazil, using hydrological and hydraulic modeling using the PCSWMM software (version 7.6.3610). The objective was to investigate the impact of urbanization on local hydrology, considering the occurrence of erosive processes in the area. Critical points in the infrastructure and regions susceptible to flooding were identified. The methodology involved implementing residential detention tanks in different allocation scenarios, including the use of isochrones. Isochrones, which represent lines of equal concentration time in the drainage network, were employed to segment the basin into three main regions: upstream (ISO 1+2), central (ISO 3+4), and downstream (ISO 5+6). The isochrone-based scenarios enabled the assessment of the impact of concentrating residential detention tanks in these specific zones. Additionally, two other scenarios were analyzed: one with the residential detention tanks uniformly distributed throughout the basin and another without the presence of these devices. Finally, a scenario with a random distribution of residential detention tanks was tested, encompassing a total of 54 distinct configurations, to investigate the influence of different spatial arrangements on the basin’s hydraulic performance. The results indicated that the number of residential detention tanks installed is the main determinant for peak flow attenuation at the basin’s outlet. It was observed that, regardless of the distribution of the devices, whether in concentrated scenarios (upstream, central, and downstream, as defined by the isochrones) or in randomly distributed configurations, the results were similar. In all cases, installing residential detention tanks in more than 30% of the basin area resulted in an approximately 5% reduction in peak flow at the outlet. It is concluded that implementing residential detention tanks is an effective and feasible solution for sustainable stormwater management, significantly contributing to surface runoff control and peak flow mitigation in urbanized areas. Full article

Polychlorinated biphenyls (PCBs) are synthetic organic compounds that were widely used in industrial applications throughout the 20th century. Due to their chemical stability, resistance to degradation and ability to bioaccumulate and biomagnify through food chains, PCBs pose long-term environmental and health risks. Due to these characteristics, PCBs have been globally regulated as persistent organic pollutants (POPs), despite being banned from production in most countries decades ago. This study investigates temporal trends in PCB contamination in urban soils of Bucharest over a 20-year period (2002–2022), focusing on six principal congeners (PCB 28, 52, 101, 138, 153, and 180) sampled from 13 locations, including roadsides and urban parks. Gas chromatography and spatial analysis using inverse distance weighting (IDW) revealed a marked reduction in Σ6PCB concentrations, declining from 0.0159 mg/kg in 2002 to 0.0065 mg/kg in 2022, with statistically significant differences confirmed by Kruskal–Wallis analysis (p < 0.05). This decline is primarily attributed to reduced emissions, source control measures, and natural attenuation. However, the persistence of PCBs in localized hotspots is influenced by secondary dispersion mechanisms, such as atmospheric deposition and surface runoff, which redistribute contaminants rather than eliminate them. Health risk assessments via ingestion, dermal absorption, and inhalation routes confirmed negligible carcinogenic risk for both adults and children. Although measurable progress has been achieved, the persistence of localized contamination underscores the need for targeted remediation strategies and sustained environmental monitoring to protect vulnerable urban areas from recontamination. Full article

Rain gardens are efficient nature-based solutions (NBSs) for the sustainable management of surface run-off in urban areas. The functionality of a rain garden in an urban environment depends on the resistance of plant and soil components to anthropogenic stressors. In temperate climates, the negative effects of de-icing chemicals applied in wintertime are one of the major anthropogenic stressors for the rain gardens’ ecosystem. The research aimed to study the effect of a NaCl-based de-icer in the mesocosm experiment, where materials of soil mixtures (seven parts by volume of quartz or carbonate sand and three parts by volume of loam or peat), plants (Hemerocallis hybrida), de-icer dose (529 mg L⁻¹ for Cl⁻ and 472 mg L⁻¹ for Na⁺ concentrations), and irrigation period simulated typical conditions for the Moscow city—the largest world megapolis with permanent snow cover during the wintertime. For all soil mixtures, a short-term negative impact of salinization on soil health included a decrease in microbial biomass (4–7-times) and basal respiration (2–3.6-times). After six months, soil health indicators recovered by 80–90% in the peat and carbonate sand mixture, whereas the negative effects on the quartz sand and loam mixtures remained irreversible (1.3 and 3 times lower than the control, respectively). The chlorophyll content of the plants on all soil mixtures was reduced compared to the control plants (37.1 ± 4.1 vs. 39.9 ± 1.2 SPAD units). The worst plat condition was observed for soil mixtures based on quartz sand. In this variant, the negative effect of salinization coincided with low nutrient content. In our results, the ash content was up to three times less compared to the initial state, as well as to the other materials. Plants grown in mixtures based on loam were more resistant to salinization due to higher nutrient content than peat. Overall, based on soil Na uptake, plant biomass, and recovery of soil microbiota, soil mixtures based on peat, loam, and carbonate sand will be the most resistant to NaCl-based de-icers and could be recommended for the creation of rain gardens in cities with permanent snow cover in winter. Full article

Nitrogen (N) and phosphorus (P) losses from sloping agricultural lands through runoff are a significant environmental concern, yet their transport mechanisms across different slope gradients are not well understood. Therefore, we built an experimental site in a subtropical hilly region of China to explore the patterns of nitrogen and phosphorus loss in tea plantations under typical slopes. We set two slope gradients of 20° and 30°, with three plots for each gradient. We quantified the loss of nitrogen (N) and phosphorus (P) through surface flow and interflow on these two slope gradients. We also collected meteorological data through the meteorological station we built. A total of 17 rainfall events were recorded. Results showed that total nitrogen (TN) and phosphorus (TP) concentrations in surface flow on the 30° slope were 8.9% and 31.6% higher, respectively, than on the 20° slope. In interflow, the differences were even more pronounced, with TN and TP concentrations 68.5% and 218.1% higher on the 30° slope. Overall nutrient loss loads (combining surface and interflow pathways) were significantly greater on the steeper slope, with TN and TP loss loads being 2.58 and 3.43 times higher on the 30° slope than on the 20° slope. The composition analysis revealed that dissolved nitrogen (DN) dominated nitrogen transport, accounting for 68.6% of TN in surface flow and 97.8% in interflow, while dissolved phosphorus (DP) represented 35.0% of TP in surface flow and 57.0% in interflow. Initially, TN and TP concentrations in surface flow were high and decreased as runoff generation time increased. Correlation analysis showed that higher temperatures increased TN and TP concentrations in surface flow. On the 30° slope, increased soil moisture promoted higher concentrations of soluble P. Instantaneous rainfall intensity was significantly correlated with TN and TP concentrations in surface flow under both slope gradients. This study revealed N and P loss patterns in tea gardens on steeper slopes, offering guidance for controlling nutrient loss in sloping farmland. Full article

Riverine heavy metal (HM) pollution, a critical global environmental issue, severely affects water quality, ecosystem health, and human well-being. The Huaihe River, once among China’s most polluted, has seen water quality improvements due to strict pollution controls, yet the extent of HM pollution reduction remains uncertain. Here, we investigated the distribution, sources, and potential ecological and health risks of nine typical HMs (Cr, Mn, Ni, Cu, Zn, As, Cd, Pb, and Hg) in surface water and sediment in the Anhui section of the river. Seasonal variations in HM concentrations were observed, with most values below drinking water safety limits, except for Mn and Cd at specific sites and seasons. Indices including the HPI, HEI, HQ, and HI showed low contamination and health risks, yet children are more vulnerable to non-carcinogenic hazards, notably from Cd and As. Sediment HMs trends decreased as Mn > Zn > Cr > Pb > Ni > Cu > As > Cd > Hg, with moderate pollution from Cd, Mn, and Pb based on CF, EF, and I_geo assessments. PLI and NPI suggested moderate ecological risks in midstream areas due to HM accumulation. The correlation analysis and PCA revealed that HMs in uncontaminated sediments were mainly of geogenic origin, while contaminated sediments were largely influenced by anthropogenic activities, including agricultural runoff, industrial waste, and domestic sewage discharge. Overall, our findings highlight that control of anthropogenic activities within the Huaihe River basin is essential for reducing HM pollution in the river. Full article