Potential Ecological Risk Index Research Articles

Sources Analysis and Health Risk Assessment of Heavy Metals in Street Dust from Urban Core of Zhengzhou, China

Fifty-one street dust samples were systematically collected from the urban core of Zhengzhou, China, and analyzed for potentially toxic metals. The concentrations of vanadium (V), manganese (Mn), copper (Cu), zinc (Zn), arsenic (As), lead (Pb), and nickel (Ni) in the samples surpassed the background values of the local soil, indicating a notable potential for contamination. Spatially, the traffic area was the most polluted with a total heavy metal concentration of Cu, Zn, As, Pb, and Ni, while the pollution levels were lower in the culture and education area and commercial area with total concentrations of V and Mn. Seasonal variations were discerned in the concentrations of heavy metals, with V, Cu, Zn, and As exhibiting heightened levels during the fall and winter, while Mn, Ni, and Pb reached peaks in the spring season. Zn exhibited the highest mean geo-accumulation index (Igeo) value at 2.247, followed by Cu at 2.019, Pb at 0.961, As at 0.590, Ni at 0.126, Mn at −0.178, and V at −0.359. The potential ecological risk index (RI) in the traffic-intensive area markedly exceeded other functional areas. Health risk assessments showed that children were more vulnerable to heavy metal exposure than adults, particularly through the ingestion pathway. Correlation analysis, principal component analysis (PCA), and cluster analysis (CA) were applied in conjunction with the spatial–temporal concentration patterns across various functional areas to ascertain the plausible sources of heavy metal pollutants. The results indicated that heavy metals in the urban street dust of Zhengzhou were multifaceted, stemming from natural processes and diverse anthropogenic activities such as coal burning, industrial emissions, traffic, and construction operations.

Heavy metals distribution and their ecological risk in the surface sediments of Haizhou Bay, China

A comprehensive analysis of heavy metal concentrations, sources, and pollution status was conducted on thirty surface sediment samples collected from Haizhou Bay, China in 2020. The spatial distributions of Cu, Pb, Zn, Cr, Cd, and total organic carbon (TOC) were found to be analogous. Noteworthy, sporadic pollution effects from Cu, Cr, and As were detected, although heavy metal concentrations remained below the probable effect level (PEL). A suite of analytical methods, including Pearson's correlation coefficient, geoaccumulation index, sediment quality guidelines, potential ecological risk index, and principal component analysis, was employed to elucidate the sources and assess the pollution risks. The results indicated that Hg emerged as the predominant heavy metal pollutant in Haizhou Bay sediments, with several stations showing high pollution levels that require attention. Other heavy metals were mainly of natural origin, indicating no significant pollution in the study area.

Determination and contamination status of mercury and other heavy metals in artisanal and small-scale gold mining at Banyumas region, Central Java, Indonesia, using ICP-OES

ABSTRACT The determination of mercury and other heavy metals (As, Cd, Cr, Ni, and Pb) has been carried out as toxic metals for the human body. Sample preparation was carried out by the microwave digested assist. The determination of heavy metals was carried out using the ICP-OES. The validation parameters used were linearity, Limit of Detection (LoD), Limit of Quantitation (LoQ), precision, and accuracy. Mercury, Arsen, Cadmium, Chromium, Nickel, and Lead average content in sediment gold ore processing waste was 1617.64, 5525.09, 20.24, 484.96, 259.67, and 1210.27 μg/kg, respectively. Linearity used a standard solution of 10–1000 μg/kg, and it produced a regression equation with r2 > 0.9992. The Limit of Detection (LoD) and the Limit of Quantitation (LoQ) was below 1.56 μg/kg and 6.27 μg/kg, respectively. The precision was calculated by the repeatability method, with a result of %RSD below 2.30%. Accuracy was obtained by recovering a spiked standard. The recovery value was found to be between 83% and 118%. Geoaccumulation Index (Igeo), Metal Pollution Index (MPI), Degree of Contamination (Cdeg), and Potential Ecological Risk Index (PERI) in this study was −8.62–1.43, 0.02–5.33, 8.80, and 168.59, respectively. The waste processing site at Artisanal and Small-Scale Gold Mining is generally contaminated by mercury and other heavy metals. All the validation parameters of the method are in the acceptability range, so the method can be used as a routine method for determining mercury and other heavy metals (As, Cd, Cr, Ni, and Pb) levels in gold ore processing waste.

Ecological risk assessment of heavy metals in surface sediments and their impact on macrobenthos in Asan Bay, South Korea

Bay ecosystems with unique economic and ecological value are more vulnerable to heavy metal pollution than other marine ecosystems. In South Korea, rapid economic development has exacerbated heavy metal pollution in bay environments. This study analyzed concentrations of seven heavy metals and the structure of macrobenthic community in Asan Bay. Five heavy metal indices (PLI, Pn, RI, TRI, and MERMQ) were used to assess ecological risk. Additionally, spearman correlation, biota–environment matching (BIO-ENV), and redundancy analysis (RDA) were utilized to determine the influence of heavy metals on macrobenthic communities. Although average concentrations of seven heavy metals were below sediment quality guidelines (SQGs), the average concentration of Cd was close to the threshold effects level (TEL). The nemerow pollution index (Pn) and the potential ecological risk index (RI) indicated that Cd was the primary heavy metal contributing to ecological risk. Spearman correlation, BIO-ENV, and RDA indicated that heavy metals were the main environmental factors influencing macrobenthic communities in Asan Bay. However, five heavy metal indices (PLI, Pn, RI, TRI, and MERMQ) did not show a response to the macrobenthic communities. Overall, low concentrations of heavy metals have a certain negative impact on macrobenthic communities in Asan Bay. This study can serve as an important reference for marine environmental protection and policy-making in Asan Bay.

Ecological and health risk assessments of heavy metals in surface water sediments from Ifite Ogwari community in Southeastern Nigeria

The hydrosphere becomes contaminated secondarily by accumulated heavy metals in sediments which may be released into the aquatic environment, thereby increasing the risks to human health. To evaluate the pollution characteristics of heavy metals in surface water sediments of Ifite Ogwari, nine sediment samples were collected from surface water sources used by the residents for drinking and other household activities. The concentrations of eight heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), Iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) were analyzed using Atomic Absorption Spectroscopy (AAS). Enrichment Factor (EF), Contamination Factor (CF), Geoaccumulation index (Igeo), Potential Ecological Risk Index (PERI) and Risk Assessment Code (RAC) were conducted. Results of heavy metal concentration indicated that Cu < Cr < Ni < Pb < Cd < Zn < Mn < Fe based on the average metal concentration. Human health assessment showed high cancer risk for children and adults in a ratio of 1 in 10000 population. PERI indicated that sediment samples from Iyiutu and Ahala streams have low potential ecological risk while samples from Ube, Tabasi and Ogbu showed moderate ecological risk whereas samples from Isiachala, Nabaloku and Atammele streams as well as Omambala river sediments were high. RAC shows no ecological risk by Zn, Pb, Ni, Cu and Mn but in Omambala river, Cr and Cd contributed to ecological risk while Fe contributed to ecological risk in all the samples. Consequently, there is need for proper monitoring from health base evaluation and conscious effort to live in a clean environment devoid of any kind of exposure.

Distribution and risk assessment of nutrients and heavy metals from sediments in the world-class water transfer projects

South-to-North Water Diversion Project, a globally renowned engineering feat, aims to address water supply issues. The sediments within reservoirs play a pivotal role in natural ecosystems, not only as habitats for diverse biota but also as repositories of heavy metals, organic matter, and other contaminants. These sediments serve as a critical interface between sediment and water bodies. This comprehensive analysis focused on the spatial patterns of nutrients, organic matter, and heavy metals in the surface layer and profiles of reservoirs, exploring their interconnectedness. Leveraging the integrated pollution index, organic pollution index, potential ecological risk index, and geo-accumulation index, an ecological risk assessment was performed. The key findings are as follows: (i) Along the Middle Route of the South-to-North Diversion Project, the nutrient and organic matter contents in sediments tends to rise with distance from the Danjiangkou Reservoir, with the TN and TC contents increasing by 2.35- and 3.05-fold, respectively. (ii) As the sediment depth increases, the carbon, nitrogen, phosphorus, and organic matter contents exhibit varying degrees of decline, with average decreases of 62.38%, 67.47%, 17.56%, and 41.83% for TN, TC, TP, and OM, respectively. (iii) Among the eight heavy metals, only manganese (Mn) and zinc (Zn) in the Yahekou Reservoir showed moderate pollution levels, according to the geo-accumulation index. The Mn content within the surface sediments of the six reservoirs ranges from 550 to 1837 mg/kg (average, 1019.5 ± 548.3 mg/kg), whereas the Zn content ranges from 89 to 360 mg/kg (average, 156.5 ± 101.6 mg/kg). (vi) Total phosphorus (TP) and total nitrogen (TN) emerged as the primary pollutants in surface sediments. Comprehensive nitrogen and phosphorus pollution assessment revealed that the surface sediment of Danjiangkou Reservoir is mildly polluted, while Baiguishan and Jiangang Reservoirs are moderately polluted, and the rest are heavily contaminated. For the Yahekou and Chaohe Reservoirs, the average pollutant content indicates moderate pollution, while the remaining reservoirs show mild pollution levels.Graphical

Soil quality and heavy metal contamination in an open dumpsite in Navrongo, Ghana.

The increasing proximity of the Dudumbia dumpsite, an open dumpsite in Navrongo, Ghana, to human settlements necessitates an investigation of the soil quality to safeguard the environment from heavy metal toxicity. This study examined the impact of waste dumping activities on the physicochemical properties of the soil, as well as the level of heavy metal (Pb, Cd, Ni, Cr, As, Hg, Cu, Mn, and Zn) contamination and associated risks. Various contamination and risk assessment tools were used, including the geoaccumulation index (Igeo), pollution load index (PLI), potential ecological risk (Er), and potential ecological risk index (PERI). The study found significant improvements in notable soil attributes such as phosphorus (P), organic carbon (C), total nitrogen (N), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), and effective cation exchange capacity, with percentage increases ranging from 50.8 to 2078.3%. Igeo values ranged from 2.07 to 6.20, indicating contamination levels from moderate to extreme. The PLI and PERI values were 16.241 and 1810, respectively. The Er values for the heavy metals ranged from 36 to 607, indicating ecological risk levels from low to very high, with Cd and Hg posing very high risks. These results suggest that while the dumpsite soil shows improvements in some characteristics favourable for plant cultivation, waste dumping significantly contributes to heavy metal contamination. The soil at the dumpsite is deteriorated and poses significant health risks, particularly due to Cd and Hg. Therefore, remediation efforts should prioritise mitigating the risks posed by Cd and Hg.

Assessing the abundance, sources, and potential ecological risk assessment of microplastics using their particle and mass units in Uiam Lake, South Korea

Microplastics (MPs) enter lakes through various pathways, including effluents from wastewater treatment plants (WWTPs), surface runoff, and improperly disposed of plastic waste. In this study, the extent of MPs pollution in Uiam Lake in fall of 2022 and spring of 2023 was assessed by determining both the number (n/m3) and mass concentrations (μg/m3) of MPs. Moreover, the correlation between water quality parameters and MP properties was analyzed, and an ecological risk assessment was conducted. MPs abundance was higher in spring than in fall, probably due to the lifting of coronavirus disease-19 restrictions, melting of ice, higher rainfall, and faster wind speed. Fragment was the dominant shape of the MPs collected, while polyvinyl chloride (PVC) and polyester/polyethylene terephthalate were the frequently detected polymer types of MPs in fall and spring, respectively. There was a moderate positive correlation between the number concentration of MPs and the total nitrogen, total phosphorus (T-P), and total organic carbon levels; in contrast, there was no significant relationship between the mass concentration of MPs and all water quality parameters. However, the abundance (μg/m3) of PVC and polymethyl methacrylate MPs were positively correlated with T-P and electrical conductivity. The pollution load index, polymer hazard index, and potential ecological risk index (PERI) were generally higher when the mass unit of MPs was used due to the presence of large-sized MPs composed of highly hazardous polymers (e.g., polyurethane, PVC, and alkyd). For instance, the PERI value of the WWTP effluent was at the very high level (>1200) in both seasons, regardless of the abundance unit of MPs. Therefore, WWTP effluents may have increased the ecological toxicity of MPs pollution in Uiam Lake.

Current state, sources, and potential risk of heavy metals in sediments of typical inner lakes in the Dongting Lake Area

The region has been increasingly experiencing environmental issues related to heavy metals (HMs) due to human activities. However, the contamination levels of HMs (Cr, Ni, Cu, Zn, As, Cd, and Pb) in various inner lakes in the Dongting Lake area remain unclear. In this study, surface sediment samples from 9 inner lakes and sediment core samples from 3 typical inner lakes were collected to evaluate the spatial distribution, contamination status, environmental and ecological risks, and possible sources of these HMs. The results showed that all HMs, except Zn, exceeded background values, with particularly high levels observed in aquaculture lakes compared to other lakes. Vertical profiles of HMs from 3 lakes show that the various types of lakes in the study area have different pollution histories. Additionally, results from Sediment quality guidelines (SQGs), Contamination factor (CF), Geo-accumulation index method (Igeo), and Hakanson potential ecological risk index (PERI) indicated that As, Cd, and Pb are the primary pollutants. The multivariate analysis concluded that Ni, Cu, Zn, As, Cd, and Pb had anthropogenic sources, primarily from agricultural, fisheries, industrial, and transportation activities, while Cr was influenced by natural factors. The results of this study enhance our understanding of sedimentary metal content in inner lakes and emphasize the importance of controlling HMs content in these lakes. This information is crucial for developing effective lake management and pollution control strategies.

Distribution, sources, impact factors and ecological risks of sediment heavy metals from typical estuarine wetlands in tropical islands

Heavy metal contamination in the estuarine wetlands of tropical islands is becoming increasingly severe. This study focused on four typical estuarine wetlands of Hainan Island, including the mangrove and seagrass areas in Lingshui County, the mangrove and seagrass areas in Xinying Port, the mangrove area in Sibi Wan, and the seagrass area in Huachang Wan. By analyzing the heavy metal content in the surface sediments of these wetlands, we investigated the distribution characteristics and levels, explored their influencing factors, and assessed ecological risk of heavy metals in these areas. It was found the accumulation of heavy metals was high from obvious sampling sites of human activities, the type of sediment could affect the adsorption of heavy metals, with silty mudflats accumulating more. TOC/TN indicated that the organic sources of mangroves were diverse, included environmental impacts and human interference. According to the soil accumulation index and potential ecological risk index in these areas, almost all heavy metals were unpolluted except for As, which showed moderate pollution levels. The overall ecological risk in these areas was relatively low. The results of principal component analysis and correlation analysis indicated that Pb, Cu, and As were primarily sourced from human activities, while Cr was mainly of natural origin. Moreover, the distribution of heavy metals in the study areas was principally affected by TOC and salinity.

Deciphering integrated soil potential ecological and human health risks attributable to industrial effluents irrigation and wheat consumption.

Iron-steel (IS) and textile (T) are among the major polluting industries worldwide which generate large quantities of effluents containing potentially toxic metals (PTMs). Irrigation application of these effluents due to freshwater shortage is a common practice in developing countries. The current research endeavors to investigate potentially toxic metals in IS and T effluents, contamination status and ecological risk assessment of irrigated soils, PTMs accumulation in grains of diverse wheat germplasm and human health risk appraisal. Soil irrigation with effluents significantly enhanced soil nitrate-nitrogen (T, 285.86mg/kg; IS, 539.70mg/kg), phosphorus (T, 8.35mg/kg; IS, 11.44mg/kg), organic matter (T, 6.05%; IS, 4.48%) and PTMs contents compared to control (C). Enrichment factor and geo-accumulation index revealed substantial contamination trend of PTMs in IS (Ni > Cr > Co > Cd > Pb > Zn > Mn) and T (Co > Cd > Ni > Cu > Cr) treated soils. Potential ecological risk index and modified potential ecological risk index placed T (very high risk) and IS (considerable risk) irrigated soils in respective categories, with highest risk contributions from Cd, Co and Ni. The interactive effects for PTMs accumulation in grains of 30 wheat genotypes were recorded significant. Average PTMs accumulation in grains for the three irrigation treatments was IS > T > C for Zn, Cr, Mn, Pb, Fe, Ni and T > IS > C for Co, Cd, Cu. Multivariate statistical analysis ( principal component analyses) was used to identify the wheat genotypes with higher or lower grain PTMs accumulative potential on effluent irrigation. The genotypes with a lower grain PTMs accumulation and human health risks are recommended for cultivation in agro-systems receiving IS and T effluents, in order to safeguard wheat crop and human health.

Health risk assessment of heavy metals in the dust street of Mehran city, as a busy city in religious times, Iran.

The concentration of various potentially toxic metals (Pb, Cd, As, Ni, Zn, and Cr) in street dust samples collected from Mehran city, Iran, was analyzed. The samples were obtained during normal traffic conditions, NTT, prior to the Arbaeen ceremony, as well as after the pilgrims' return, which corresponds to high traffic time, HTT. Street dust samples were analyzed for HM content using ICP-OES, following acid digestion. The subsequent evaluation of the data involved the application of the geo-accumulation index, enrichment factor, and potential ecological risk index (PER) and health risk assessment. The findings demonstrate a notable increase in the levels of HMs during HTT compared to the NTT. The highest enrichment values for Pb and Cd were observed in Mehran Street dust during the HTT. The mean of PER for all sampling points increased to 138.24, indicating a moderate-potential ecological risk at this time. Based on the health risk assessment, it was found that the hazard index for all samples was below one. The incremental lifetime cancer risk was below 10-6. This indicates that the exposed population is not exposed to substantial health risks. Despite the heavy traffic caused by the Arbaeen ceremony in this area and the high enrichment of HMs, along with potential ecological risks, no significant health risks were observed for individuals exposed to street dust. However, it is important to note that the continuation of this trend, in the absence of proper traffic management, could lead to significant environmental and health problems in the future.

Elemental profiling of agricultural soil in Hoshiarpur utilizing analytical techniques.

Our study aimed to assess the soil quality in Punjab's Hoshiarpur district through a meticulous analysis of nutrient and elemental composition. Using a variety of analytical techniques, including Neutron Activation Analysis (NAA), external Particle-induced Gamma-ray Emission (PIGE) an Ion beam analysis Technique, and energy-dispersive X-ray fluorescence (ED-XRF), we delved into soil characterization for 22 agricultural soil samples in the Punjab region. Within the NAA framework, utilizing the Pneumatic Carrier Facility and the self-serve facility at Dhruva reactor in Mumbai, a brief 1-min irradiation procedure identified pivotal elements-Na, Mg, V, Al, Mn, and K. Conversely, an extended neutron irradiation process of approximately 4h within the self-serve facility enabled the estimation of nearly 12 elements, including Rare Earth Elements (REEs), Transition elements, and other significant elements. The external PIGE technique quantified low Z elements (Na, Mg, Al, and Si), contributing to our analytical arsenal. Rigorously validating both NAA and PIGE methodologies, we compared results meticulously against established geological standard reference materials-specifically USGS RGM-1 and USGS AGV-1.Instrumental in elemental analysis, ED-XRF spectroscopy fortified our investigative endeavors by quick assessment of ten crucial elements. The elemental analysis revealed notable accumulations of Mn and Zn in the soil, surpassing the suggested permissible limits, whereas Co, Cr, and Pb were found to be within the recommended thresholds set by WHO/UNEP. Beyond elemental profiling, our study extended to estimate the accumulation levels of various elements utilizing ecological risk factors such as Contamination Factor, Potential Ecological Risk Index, Pollution Load Index, and Geoaccumulation Factor. Our findings highlighted significant accumulation of REEs including La, Sm and Yb.. This evaluation sheds new light on the interplay between soil composition and environmental health, emphasizing the need for advanced accessible agricultural technologies to prevent and forecast contaminant discharge in arable soil. This commitment aligns with our broader goal of advancing sustainable practices in soil management.

Cumulative characteristics and ecological risk source analysis of soil potentially toxic elements in the northern margin of the Tibetan Plateau.

To understand the soil toxic and hazardous elements content, pollution level, and ecological risk status in the northern margin of the Tibetan Plateau, we collected and analyzed 8273 sets of surface soil samples. Evaluations were conducted using the single-factor pollution index, geo-accumulation, pollution load, and potential ecological risk indices, and source identification correlation and principal component analysis. The results revealed that, compared with the background levels in China, the accumulation of soil arsenic, cadmium, nickel, and chromium was greater in the surface soil of the study area. Additionally, in comparison with Qinghai Province, more mercury accumulated in the surface soil of the study area and owing to the influence of anthropogenic activities. Benchmarking against soil environmental quality standards, the study area exhibited pollution control zones primarily dominated by arsenic and cadmium (3.9%). The spatial distribution revealed distinct zones: a ridge mountain type characterized by arsenic-cadmium-chromium-nickel, a Daban mountain type with solely cadmium presence, and a Longyangxia-Jianzha South type dominated by arsenic. Compared with the Qinghai Province soil background values, evaluations using the Pollution loading index, Geological Cumulative Index, and Potential Ecological Risk Index methods revealed varying degrees of potentially toxic element content exceedance. From an ecological risk perspective, the individual element with the highest potential ecological risk coefficients were mercury, followed by cadmium and arsenic; however, the region's overall ecological risk index was classified as low. Three distinct sources were identified: natural sources leading to high background levels of chromium, nickel, copper, zinc, and mercury; mixed natural and industrial/agricultural sources contributing to elevated cadmium levels; and human activity-related mercury enrichment. Based on the evaluation results, synergistic monitoring of soil and biota in naturally occurring risk zones is recommended to ensure the safety of agricultural and pastoral products. Additionally, ecological impact assessments and pollution source mitigation studies should be conducted in regions influenced by human activities to curb the further degradation of soil ecological quality.

Characteristics, sources and potential ecological risk of atmospheric microplastics in Lhasa city

Atmospheric microplastics are important contributors to environmental contamination in aquatic and terrestrial systems and pose potential ecological risks. However, studies on atmospheric microplastics are still limited in urban regions of the Tibetan Plateau, a sentinel region for climate and environmental change under a warming climate. In this study, the occurrence and potential ecological risk of atmospheric microplastics were investigated in samples of suspended atmospheric microplastics collected in Lhasa city during the Tibetan New Year in February 2023. The results show that the average abundance of atmospheric microplastics in Lhasa was 7.15 ± 2.46 MPs m−3. The sizes of the detected microplastics ranged from 20.34 to 297.18 μm, approximately 87% of which were smaller than 100 μm. Fragmented microplastics (95.76%) were the dominant shape, followed by fibres (3.75%) and pellets (0.49%). The primary polymer chemical components identified were polyamide (68.73%) and polystyrene (16.61%). The analysis of meteorological data and the backwards trajectory model indicated the air mass in Lhasa mainly controlled by westwards, and the atmospheric microplastics mainly originated from long-distance atmospheric transport. The potential ecological risk index assessment revealed that the atmospheric microplastic pollution in Lhasa was relatively low. This study provides valuable insights and a scientific foundation for future research on the prevention and control of atmospheric microplastic pollution in Lhasa and other ecologically sensitive cities.

Analysis of heavy metal and arsenic sources in mangrove surface sediments at Wulishan Port on Leizhou Peninsula, China, using the APCS-MLR model

Mangrove forests are sources and sinks for various pollutants. This study analyzed the current status of heavy metal and arsenic (As) pollution in mangrove surface sediments in rapidly industrializing and urbanizing port cities. Surface sediments of mangroves at Wulishan Port on the Leizhou Peninsula, China, were analyzed using inductively coupled plasma emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) for the presence of Cr, Pb, Ni, Zn, Cd, Cu, As, and Hg. The Pollution load index, Nemerow pollution index, and Potential ecological risk index were employed to evaluate the pollutant. Multivariate statistical methods were applied for the qualitative analysis of pollutant sources, and the APCS-MLR receptor model was used for quantification. This study indicated the following results: (1) The average content of eight pollutants surpassed the local background level but did not exceed the Marine Sediment Quality standard. The pollution levels across the four sampling areas were ranked as Ⅲ > Ⅳ > Ⅰ > Ⅱ. The area Ⅱ exhibited relatively lower pollution levels with the grain size of the sediments dominated by sand, which was not conducive to pollutant adsorption and enrichment. (2) The factor analysis and cluster analyses identified three primary sources of contamination. As, Cr, Ni, and Pb originated from nearby industrial activities and their associated wastewater, suggesting that the primary source was the industrial source. Cd, Cu, and Zn stem from the cement columns utilized in oyster farming, alongside discharges from mariculture and pig farming, establishing a secondary agricultural source. Hg originated from ship exhaust burning oil and vehicle emissions in the vicinity, representing the third traffic source. (3) The APCS-MLR receptor model results demonstrated industrial, agricultural, and traffic sources contributing 47.19 %, 33.13 %, and 13.03 %, respectively, with 6.65 % attributed to unidentified sources.

Quantifying microplastics in sediments of Jinzhou Bay, China: Characterization and ecological risk with a focus on small sizes

Small-sized microplastics (MPs) pose greater ecological toxicity due to their larger surface area, which makes them more likely to act as carriers for other pollutants and to be ingested by aquatic organisms. However, traditional visual analysis often neglects small-sized MPs and their associated ecological risk. This study utilized Laser Direct Infrared (LDIR) spectroscopy and traditional visual analysis to examine MPs in 31 sediment samples from Jinzhou Bay, a typical semi-enclosed bay located at the economic center of Dalian, China. The results showed significant heterogeneity in MP distribution, with averages of 1192 and 2361 items/kg dry weight reported by visual analysis and LDIR spectroscopy, respectively. LDIR spectroscopy identified MPs as small as 10 μm, with the majority of MPs (89.21 %) within the 10–250 μm range, and a significant proportion (46.45 %) between 10 and 50 μm among them. However, visual analysis was limited to detecting MPs >50 μm, and significant portions were identified between 50 and 100 μm (49.36 %) and 100–250 μm (31.01 %), missing a substantial fraction of smaller MPs. The predominant polymers identified were polyamide (PA), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and acrylonitrile butadiene styrene (ABS). LDIR spectroscopy demonstrated a strong positive correlation between MP abundance and clay content, a relationship not observed with traditional visual analysis. The Potential Ecological Risk Index (PERI) indicated that over 87 % of sites posed an extremely high risk according to LDIR spectroscopy, compared to 51 % by traditional visual analysis. These discrepancy underscores the underestimation of ecological risks by traditional methods, particularly for small-sized MPs. High-risk polymers such as polyvinyl chloride (PVC), ABS, and polyurethane (PUR) significantly influenced PERI values. These findings highlight the critical need for precise identification and thorough risk assessment of small-sized MPs in environmental studies and offer insights for understanding of MP vertical migration in aquatic environments, particularly in the context of co-settlement with sediments.

Evaluation of potentially toxic metals in tailings from Busia gold mine fields of eastern Uganda

Busia Gold mines in eastern Uganda generate significant wastes that contribute to environmental and health challenges in the region. This study assessed the extent of 9 potentially toxic metals (PTMs) present in Busia gold mine tailings. The study also evaluated environmental risks for each of the PTMs, using contamination indices. The indices were: index of geo accumulation (Igeo); potential ecological risk index (RI); contamination factor (CF); pollution load index (PLI) and ecological risk factor (ERI). Tailing samples were collected at two distinct depths; surface (0–30 cm) and deep (30–60 cm) from four sites. The samples were analyzed using an Atomic Absorption Spectrometry (AAS). The Igeo results showed that As and Hg recorded extreme pollution levels (Igeo >5) in all 4 sites. The other seven PTMs in all the sites were classified between heavily polluted to unpolluted categories. CF results revealed extreme contamination for Hg at site-A and As at site-M with moderate contamination of Ni, Zn, and Co at sites-C and B. RI findings showed that all the sites recorded RI > 600, with the highest (RI = 80, 407) at site-A, followed by site-C (RI = 74, 536). All the sites had a high level of ecological impact with greater potential for environmental risks in the area. In the case of PLI, all the sites were classified as polluted sites (PLI > 1). Sites-M and C recorded the highest (PLI = 12), followed by sites-B and A, with PLIs of 11 and 9, respectively. ERI findings for all the sites showed significant Hg, As, and Cd contamination, (ERI >320). Site-A recorded the highest Hg contamination (ERI = 78, 825). Site-M recorded elevated levels of As and Cd, with ERI of 1, 323, and 399, respectively. Pb at site-M posed considerable potential ecological risk with an ERI of 108, while Zn, Cu, Co, Ni, and Cr presented low ecological risk across all sites with ERI˂ 40. There is, therefore, need to properly manage tailings in Busia gold fields to minimize ecological contamination to avoid impacts on human, animal, and plant health.

Plant litter as a heavy metal migration strategy following application of sewage sludge to subtropical forest soils

The environmental risks of migration of heavy metals (HMs) following applications of sewage sludge (SS) to forest soils are garnering increased attention. Plant litter at the forest floor may modify HM migration pathways through impacts on soil aggregates and water/soil erosion; however, HM migration responses to plant litter are poorly understood. The aim of this study was to determine the effects of plant litter cover on HMs migration, and water and soil erosion following the application of SS to subtropical forest soils. Effects of addition of SS along and SS plus plant litter at 0.75 or 1.5 kg m−2 on the migration of cadmium, chromium, copper, nickel, lead, and zinc in surface runoff, soil interflow, and sediments were quantified across nine simulated rainfall events in a laboratory experiment and following natural intense rain events in a field experiment. Addition of SS elevated HM concentrations in surface runoff by 38.7 to 98.5 %, in soil interflow by 48.3 to 312.5 %, and in sediment by 28.5 to 149.4 %, and increased the production of sediment aggregates <0.05 mm that led to greater cumulative migrations of HMs in surface runoff and sediment; sediment accounted for 89.5 % of HM migrations. Addition of plant litter reduced cumulative migration of HMs by 87.1–97.27 %; however, the higher rate of plant litter led to a decrease in surface runoff and sediment yield, and an increase in soil interflow. Addition of plant litter shifted the main pathway of HM migration from sediment to surface runoff and soil interflow. The potential ecological HM risk index was “low” for each treatment. We found consistency in HM concentrations and migrations via surface runoff between the field and laboratory experiments. Overall, the addition of plant litter with SS mitigated soil erosion and reduced total migration of HMs, resulting in a 88.7–97.3 % decrease in the ecological risk index of the six HMs. We conclude that the addition of plant litter may provide a management strategy for the mitigation of HM risks to environmental safety for the disposal of SS in subtropical forest systems.

Characteristics of Pollution and Microbial Community Structure in the Antimony Mining Area of Longnan, Gansu Province

Antimony （Sb） is a major pollutant that poses a serious threat to the environment in the mining and processing of nonferrous metals, coexisting with sulfide and oxide of arsenic （As）. Microorganisms play an important role in the migration, transformation, and repair of metals in soil. The ecological effects of bioavailable Sb and As on the microbial community in antimony mining areas（mining and smelting areas）are still poorly understood. The Wenzel method and high-throughput 16S rDNA amplicon were used to characterize soil pollution characteristics in different functional areas, and the relationship between the bacterial community and bioavailable concentrations have been investigated comprehensively. The results showed that： Chemical speciation of Sb and As were amorphous, and poorly crystalline hydrous oxides of Fe and Al （F3） &gt; well-crystallized hydrous oxides of Fe and Al （F4） &gt; residual phases （F5） &gt; specifically adsorbed （F2） &gt; non-specifically adsorbed （F1）. According to the estimation of the potential ecological risk index （RI） and geo-accumulation index （Igeo）, the Sb pollution degree was： smelting area &gt; mining area &gt; contrast area, in which the smelting area showed serious pollution, and the mining area showed moderate to severe pollution. The As pollution degree was： mining area &gt; smelting area &gt; contrast area, in which the mining area and smelting area showed moderate to severe pollution. High-throughput 16S rDNA amplicon showed that Proteobacteria was the most abundant phylum in mining and smelting areas； Kaistobacter, Pseudomonas, Sphingomonas, and Lysobacter were the most abundant microbial genera； Geobacter and Luteolibacter had a high LDA score in mining areas； and Thiobacillus had a high LDA score in antimony-contaminated areas. Spearman correlation analysis, variation partitioning analysis （VPA）, and random forest （RF） analysis showed that Sb, As, bioavailable antimony [Sb （Bio）], and bioavailable arsenic [As （Bio）]were the main factors affecting the microbial community structure in different functional areas of antimony ore. Redundancy analysis （RDA） indicated that Sb and its bioavailable concentrations showed uniformly negative associations with the relative abundance of bacteria Nitrospirae and showed a significant positive correlation with Thiobacillus （P<0.05）. The in-depth research on the ecological effects of bioavailable Sb and As on the bacterial community provides references and new perspectives for environmental monitoring and management.