Comprehensive Pollution Research Articles

Input Flux and the Risk of Heavy Metal(Loid) of Agricultural Soil in China: Based on Spatiotemporal Heterogeneity from 2000 to 2021

Identifying the current status of the heavy metal(loid) input of agricultural soils is vital for the soil ecological environment of agricultural-producing areas. Most previous studies have typically carried been out in small regions with limited sampling sites, which is insufficient to reveal the overall status of China. This study reviewed publications from over the past 20 years and calculated the input fluxes of heavy metal(loid)s in agricultural soil via atmospheric deposition, fertilizer, manure, and irrigation in different regions of China based on spatiotemporal heterogeneity using a meta-analysis, providing more accurate and reliable results. It was found that the heavy metal(loid) input flux of atmospheric deposition in China is large, while that of fertilizer and manure is relatively low compared to Europe. The major sources of As, Cd, Cr, Ni, and Pb entering the soil was atmospheric deposition, which accounted for 12% to 92% of the total input. Manure was responsible for 19% to 75% of the Cu and Zn input. Cd is the element presenting the most significant risk to the environment of agricultural soils in China and its safety limit will be reached within 100 years for most regions. The region we need to be concerned about is Huang-Huai-Hai due to its comprehensive pollution.

Ecological Risk Assessment and Source Apportionment of Heavy Metals in Mineral Resource Base Based on Soil Parent Materials

Mineral resource bases have dual properties, e.g., mineral resources and environmental pollution. The latter could be classified into natural and anthropogenic pollution based on identifying the spatial distribution characteristics and sources of heavy metals in the soil. The Hongqi vanadium titano-magnetite mineral resources base in Luanping County, Luanhe watershed, was taken as the research object. The geo-accumulation index (Igeo), Nemerow comprehensive pollution index (PN), and potential ecological risk (Ei) were utilized to assess the soil heavy metal pollution characteristics, and redundancy analysis (RDA) and positive determinate matrix factorization (PMF) were employed to identify sources of the soil heavy metals. The results revealed that the mean contents of Cr, Cu, and Ni in the parent material of medium-basic hornblende metamorphic rock and medium-basic gneisses metamorphic rock were 1-2 times that in other parent materials in the concentrated area of mineral resources. However, the mean contents of Pb and As were lower. Fluvial alluvial-proluvial parent materials had the highest mean content of Hg, and the mean content of Cd was higher in the parent materials of medium-basic gneisses metamorphic rocks, acid rhyolite volcanic rocks, and fluvial alluvial-proluvial facies. The Igeodecreased in the following order:Cd>Cu>Pb>Ni>Zn>Cr>Hg>As. PN ranged from 0.61 to 18.99, and the sample proportion of moderate and severe pollution reached 10.00% and 8.08% respectively. Pishowed that the contents of Cu, Cd, Cr, and Ni were relatively higher in the parent material of intermediate-basic hornblende metamorphic rocks and intermediate-basic gneiss metamorphic rocks. Ei decreased in the order of Hg(58.06)>Cd(39.72)>As(10.98)>Cu(6.56) >Pb(5.60)>Ni(5.43)>Cr(2.01)>Zn(1.10). Samples whose RI was lower than 150 accounted for 84.27%, showing that the research area was predominantly at a slight potential ecological risk level. The sources of soil heavy metals were dominated by parent material weathering, followed by the mixed sources of agricultural activities and transportation, the exploitation of mining, and fossil burning, which accounted for 41.44%, 31.83%, 22.01%, and 4.73%, respectively. The risks of heavy metal pollution in the mineral resource base were characterized as multi-source instead of the single source from the mining industry. These research results provide the scientific basis for regional green mining development and eco-environmental protection.

Seasonal Variation Characteristics and Pollution Assessment of Heavy Metals in Water and Sediment of Taipu River

Taipu River is a river spanning two provinces and one city in a demonstration area in the Yangtze River Delta on an ecologically friendly developmentand an important water source in the upper reaches of the Huangpu River in Shanghai. To understand the multi-media distribution characteristics, pollution status, and ecological risk of heavy metals in the Taipu River, the contents of heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, and Zn) in the sediments of Taipu River were analyzed, and the pollution status and potential ecological risk were evaluated using the Nemerow comprehensive pollution index, geo-accumulation index, and potential ecological risk index methods. In addition, the health risk assessment model was used to assess the health risk of heavy metals in surface water of Taipu River. The results showed that the concentrations of Cd, Cr, Mn, and Ni in the surface water of Taipu River exceeded the class Ⅲ water limit at the upstream point in spring; the concentrations of Sb exceeded the class Ⅲ water limit at all points in winter; the average value of As exceeded the class Ⅲ water limit in overlying water during the wet season; and the average values of As and Cd exceeded the class Ⅲ water limit in pore water during the wet season. The health risk assessment of surface water implied that both adults and children had higher health risk in spring and lower health risk in other seasons. The health risk of children was significantly higher than that of adults, and it mainly came from chemical carcinogenic heavy metal elements As, Cd, and Cr. The average contents of Co, Mn, Sb, and Zn in Taipu River sediments in the four seasons all exceeded the Shanghai soil baseline; the average contents of As, Cr, and Cu in summer, autumn, and winter exceeded the Shanghai soil baseline; and the average contents of Cd, Ni, and Pb in summer and winter exceeded the Shanghai soil baseline. The evaluation results of the Nemerow comprehensive pollution index and geo-accumulation index showed that the pollution degree of the middle reaches of Taipu River was higher than that of the upper and lower reaches, and the Sb pollution was more serious. The potential ecological risk index method revealed that the Taipu River sediment was at a low risk. Cd had a high contribution in both the wet and dry seasons and could be regarded as the main heavy metal of potential ecological risk in the Taipu River sediment.

A comparative assessment of the lagoons with water quality indexes and based on GIS: A study on the Aegean Sea and Mediterranean Sea

In this study, the current status of water quality in Güllük Lagoon and Köyceğiz-Dalyan Lagoon was examined by comparison using water quality indexes, multivariate statistical analyses and geographical information systems. Water quality parameters comprised of 9 variables i.e., WT, pH, DO, NO2-N, NO3-N, NH4-N, TP, SSM, BOD5 were measured in Güllük Lagoon and Köyceğiz-Dalyan Lagoon. Although there are important activities such as earthen pond fish farms, fish hatcheries, feldsbat and marble quarries, streams carrying domestic wastes, port, secondary residences and agricultural activities in Güllük Lagoon, there are intense tourism and agricultural activities in Köyceğiz-Dalyan Lagoon. The average concentrations of DO, TP, NO2-N results in Güllük Lagoon and DO, TP and NH4-N results in Köyceğiz-Dalyan Lagoon were determined in second class water quality according to surface water quality criteria. While both lagoons were found to be in “Good” quality class as a result of water quality index, Güllük Lagoon was found to be “medium polluted” and Köyceğiz-Dalyan Lagoon was found to be “slightly polluted” quality class as a result of comprehensive pollution index. It was observed that water quality index values of both lagoons decreased in the dry season, while their comprehensive pollution index values increased in the dry season. On the basis of the general averages of water quality index, it was found as Köyceğiz-Dalyan Lagoon (85.0) > Güllük Lagoon (84.05), and on the basis of the general averages of comprehensive pollution index, it was found as Güllük Lagoon (1.34) > Köyceğiz-Dalyan Lagoon (0.79). Relationships between variables were determined by geographical information systems (IDW technique) and statistical analyses (Descriptive statistics, Spearman rho correlation, Kruskal-Wallis test, multiple linear regression and Principal component analysis). As a result of multiple linear regression analysis in measured parameters, it was determined that the most important parameter affecting the water quality index in Güllük Lagoon was NH4-N, and the most important parameter affecting the comprehensive pollution index was SSM. In Köyceğiz-Dalyan Lagoon, it was observed that the water quality index was affected by the WT parameter and the comprehensive pollution index was affected by the SSM parameter. There is no difference in the concentrations of the average water quality parameters measured in both lagoons, and both lagoons are generally in the first and second class surface water quality class. However, Güllük Lagoon, which contains more different pollutant sources than Köyceğiz-Dalyan Lagoon, is shown to be more polluted according to water quality indexes. In addition, it has been determined that SSM is the most important parameter that determines the water quality among the measured water quality parameters of both lagoons.

Assessment of the impact of wastewater from an abattoir in Oyo state on groundwater in Onidundu community, Nigeria

Abstract. This study aimed to assess the composition of wastewater from the Oyo Central Abattoir and its possible impact on the surrounding groundwater (wells) in Onidundu community as users use them for economic and recreational purposes without being fully aware of the hazard the water can cause. For this purpose, wastewater and groundwater were analyzed for seven physicochemical parameters, verified by standard methods and compared with World Health Organization (WHO) standards. All physicochemical parameters evaluated were within acceptable limits, except for biochemical oxygen demand (BOD), dissolved oxygen (DO), total dissolved solids (TDS), total dry matter (TS) and hardness in some of the water sources. Three microorganisms (Escherichia coli, Citrobacter sp. and Klebsiella sp.) were isolated and identified by standard procedures. Water Quality Index (WQI) and Comprehensive Pollution Index (CPI) were applied to assess water quality. The WQI values ranged from 1.06 to 2.30, while the CPI score ranged from 1.02 to 1.82 among the sampled water sources. Those indices classify the waters as moderately polluted and excellent, respectively, but also due to the high numbers (0.86 × 105 CFU/mL to 4.84 × 105 CFU/mL) of pathogenic microorganisms due to microbial pollution, the analyzed water samples are not suitable for drinking, aquaculture and other household activities. Waste treatment in slaughterhouses, well water intended for domestic use, dug deep and away from waste disposal sites, are recommended to prevent possible hazards to the environment and public health.

Monitoring the dynamics of acid mine drainage affected stream surface water hydrochemistry at Jaintia Hills, Meghalaya, India.

Streams are pristine natural life-thriving water sources for people living in the mountainous proximity of NE India, where water scarcity is a common occurrence in most villages and towns. In the last few decades, factors like coal mining had drastically reduced the usability of stream water in the region; as such, an attempt has been made to assess the spatiotemporal variation of stream water chemistry affected by acid mine drainage (AMD) at Jaintia Hills, Meghalaya. The water variables were subjected to a multivariate statistical technique of principal component analysis (PCA) to understand their condition at each sampling point while comprehensive pollution index (CPI) and water quality index (WQI) was incorporated to assess the quality status. Maximum WQI was recorded in S4 (541.14) during summer, while minimum value was estimated in winter at S1 (14.65). Throughout the seasons, the WQI revealed "Good" quality in S1 (unimpacted stream), while the impacted streams (S2, S3, and S4) exhibited a "Very poor" to "Water unsuitable for drinking" status. Similarly, in S1, the CPI showed a ranged value of 0.20 to 0.37, presenting a water quality status of "Clean to Sub-Clean," whereas, CPI of the impacted streams indicated "Severely polluted" status. In addition, PCA bi-plot presented higher affinity of free CO2, Pb, SO42-, EC, Fe, and Zn in AMD-impacted streams than in unimpacted streams. The result demonstrates the environmental issues induced by coal mine waste and in particular, stream water being severely affected by AMD in mining areas of Jaintia Hills. Thus, measures to stabilized the mine repercussions and cumulative effects on the water bodies need to be formulated by the government, as stream water will remain the primary water source for the tribal communities in this region.

Toxicological Evaluation of Contamination by Potentially Toxic Elements (PTEs) and Related Risks in the Surface Waters of Three Tidal Streams of the Niger Delta, Nigeria

This work investigated the physicochemical parameters and potentially toxic elements (PTEs) in the surface water samples collected from three tidal streams (Bonny, Krakrama and Buguma) in the Niger Delta, Nigeria. Potentially toxic elements such as arsenic (As), boron (B), cadmium (Cd), cobalt, (Co), chromium (Cr), lead (Pb), nickel (Ni) and selenium (Se) were analysed using atomic absorption spectrophotometer. Physicochemical parameters were evaluated in situ using portable instruments and also in the laboratory. These parameters and PTEs were used to compute the water quality index, comprehensive pollution index, pollution load index, metal evaluation index, and toxicity load index. The ecological and health risks were also analysed. The PTEs found in the water samples were higher than the acceptable limit by WHO standards and followed the trend of Ni > Pb > Cr > Co > Se > As > Cd > B. Nickel was the most abundant element in water with the maximal concentration of 5510 µg L-1. The calculated contamination indices concluded that the streams were extensively polluted. Based on the permissible toxicity loads, maximum of 99%, 100%, 98%, 98%, 100%, 99%, and 97% of As, Cd, Co, Cr, Pb, Ni and Se respectively should be removed from the surface water of the streams in the Niger Delta to address safety and health. The PTEs in water exerted very high ecological risks. Overall, the estimated lifetime cancer risk of PTEs due to ingestion of water at Bonny, Krakrama and Buguma streams were 5.72 x 10-3, 2.88 x 10-3 and 2.3 x 10-3 respectively. The results guide controlling the PTE pollution and important information on PTEs for the formulation of the necessary remediation policies to improve water quality and protect the human health of dwellers along the Niger Delta.

Biomonitoring trace metal contamination in Guangzhou urban parks using Asian tramp snails (Bradybaena similaris)

Anthropogenic activities have caused environmental metal contamination in urban areas. Biomonitoring using organisms such as invertebrates can evaluate metal pollution, supplementing chemical monitoring, which cannot comprehensively reflect how metals influence organisms in the urban environment. To assess metal contamination in Guangzhou urban parks and its source, Asian tramp snails (Bradybaena similaris) were collected from ten parks in Guangzhou in 2021. The metal concentrations (Al, Cd, Cu, Fe, Mn, Pb, and Zn) were measured by ICP–AES and ICP–MS. We evaluated the metal distribution characteristics and correlations among metals. The probable sources of metals were determined by the positive matrix factorization (PMF) model. The metal pollution levels were analysed using the pollution index and the Nemerow comprehensive pollution index. The mean metal concentrations were ranked Al > Fe > Zn > Cu > Mn > Cd > Pb; metal pollution level in the snails was ranked Al > Mn > CuFe > Cd > Zn > Pb. Pb–Zn–Al–Fe–Mn and Cd–Cu–Zn were positively correlated in all samples. Six major metal sources were identified: an Al–Fe factor corresponding to crustal rock and dust, an Al factor related to Al-containing products, a Pb factor indicative of traffic and industries, a Cu–Zn–Cd factor dominated by the electroplating industry and vehicle sources, an Mn factor reflecting fossil fuel combustion, and a Cd–Zn factor related to agricultural product use. The pollution evaluation suggested heavy Al pollution, moderate Mn pollution, and light Cd, Cu, Fe, Pb, and Zn pollution in the snails. Dafushan Forest Park was heavily polluted; Chentian Garden and Huadu Lake National Wetland Park were not widely contaminated. The results indicated that B. similaris snails can be used as effective biomarkers for monitoring and evaluating environmental metal pollution in megacity urban areas. The findings show that snail biomonitoring provides a valuable understanding of the migration and accumulation pathways of anthropogenic metal pollutants in soil‒plant–snail food chains.

Accumulation characteristics and risk of heavy metals and microbial community composition in bioretention systems: A case study of a university campus

Bioretention systems have proven to be an effective stormwater treatment technology for reducing runoff pollution. However, the accumulation risk of heavy metals and characteristics of the microbial communities in the filter media is still unclear under long-term runoff infiltration. This paper reports on a field study that investigated the ecological impact of common heavy metals and the structures of microbial communities in nine bioretention systems during two seasons. Samples were collected from the filer media to determine the concentrations of heavy metals and the microbial information was obtained by high-throughput sequencing technology. The results indicated that Cr, Ni, Cu, and Zn accumulated significantly in the bioretention system, with mean concentrations 2–3 times higher than the corresponding background values. Heavy metals were mainly trapped in the surface media (0-10 cm) and concentrations varied with season. The comprehensive pollution status of the bioretention systems was at a light to medium level. In particular, Ni accounted for the majority of the potential ecological risk index values, with an ecological hazard of above moderate levels. The results of high-throughput sequencing showed that Actinobacteria (22.51–42.16%) and Proteobacteria (19.67–34.46%) are the dominant phyla in the bioretention media under the long-term pollutants accumulation. Microbial diversity was negatively correlated with the heavy metals content of the media (p < 0.05). Heavy metals inhibited the growth and reduced the diversity of media microorganisms to varying degrees, with Ni contributing the most to microbial community changes. Our findings are expected to help in controlling the heavy metals pollution in the bioretention systems and provide practical guidance regarding the systems operation and media micro-ecosystem maintenance.

Ascertaining priority control pollution sources and target pollutants in toxic metal risk management of a medium-sized industrial city

Re-suspended surface dust (RSD) often poses higher environmental risks due to its specific physical characteristics. To ascertain the priority pollution sources and pollutants for the risk control of toxic metals (TMs) in RSD of medium-sized industrial cities, this study took Baotou City, a representative medium-sized industrial city in North China, as an example to systematically study TMs pollution in RSD. The levels of Cr (242.6 mg kg−1), Pb (65.7 mg kg−1), Co (54.0 mg kg−1), Ba (1032.4 mg kg−1), Cu (31.8 mg kg−1), Zn (81.7 mg kg−1), and Mn (593.8 mg kg−1) in Baotou RSD exceeded their soil background values. Co and Cr exhibited significant enrichment in 94.0 % and 49.4 % of samples, respectively. The comprehensive pollution of TMs in Baotou RSD was very high, mainly caused by Co and Cr. The main sources of TMs in the study area were industrial emissions, construction, and traffic activities, accounting for 32.5, 25.9, and 41.6 % of the total TMs respectively. The overall ecological risk in the study area was low, but 21.5 % of samples exhibited moderate or higher risk. The carcinogenic risks of TMs in the RSD to local residents and their non-carcinogenic risks to children cannot be ignored. Industrial and construction sources were priority pollution sources for eco-health risks, with Cr and Co being the target TMs. The south, north and west of the study area were the priority control areas for TMs pollution. The probabilistic risk assessment method combining of Monte Carlo simulation and source analysis can effectively identify the priority pollution sources and pollutants. These findings provide scientific basis for TMs pollution control in Baotou and constitute a reference for environmental management and protection of residents' health in other similar medium-sized industrial cities.

Distribution and Pollution Assessment of Nutrients in the Surface Sediments of Lake in Huoqiu County

To clarify the spatial distribution and pollution characteristics of nutrients in the surface sediments of Chengxi Lake and Chengdong Lake in Huoqiu County, total nitrogen (TN), total phosphorus (TP), and organic matter (OM) in 30 surface sediment samples of Chengxi Lake and Chengdong Lake were determined, and their pollution levels and sources were analyzed. The results showed that the contents of total nitrogen (TN), total phosphorus (TP), and organic matter (OM) in Chengxi Lake were significantly higher than those in Chengdong Lake, and their average contents were 746.23 mg·kg-1, 538.38 mg·kg-1, and 1.17% and 470.80 mg·kg-1, 492.08 mg·kg-1, and 0.68%, respectively. The spatial distribution in the north and northwest of Chengxi Lake was significantly higher than that in other areas and decreased from north to south. The C/N value indicated that the organic matter in Chengxi Lake and Chengdong Lake mainly came from unbundled plants and phytoplankton. Correlation analysis showed that total nitrogen (TN), total phosphorus (TP), and organic matter (OM) in Chengxi Lake and Chengdong Lake were homologous. The average values of TN and TP single index (STN and STP) of sediments in Chengxi Lake and Chengdong Lake were 0.67 and 1.18 and 0.42 and 1.08, respectively, indicating that TN in the two lakes was clean whereas TP was moderately polluted, and the average comprehensive pollution index (FF) was 1.51 and 1.31, respectively. The evaluation of organic index and organic nitrogen index showed that both Chengxi Lake and Chengdong Lake were clean.

Evaluation of surface water quality near pollution sources in Buriganga River and deciphering their probable emergence, ecological, and health risk aspects

Potentially toxic elements (PTEs) contamination in Buriganga river water, provoked by the point and non-point sources, has recently become a major health concern. Concentration, pollution degree, drinking and irrigation water potentiality, and associated health risks are the factors considered for this study. This study ascertained a mean pH, EC, TDS, and salinity value of 6.96, 86.25 μS/cm, 51.86 mg/L, and 86.56%, respectively, revealing that it is safe for drinking and agricultural purposes. Furthermore, the mean value of major anion (NO3−2 : 1.16, SO4−2 : 13.40, PO4−3 : 0.66, Cl−1 : 14.71 mg/L) and major cations (Na+1 : 16.95, K+1 : 4.26, Ca+2 : 17.63, and Mg+2 : 5.47 mg/L) also estimated safe for human consumption and agricultural use. Trace element evaluation index (TEI) value was found to vary among the sites and ranging from 4.40 to 10.50, indicating moderate pollution and risk imposed by the single PTEs can be ranked as Mn>Fe>Pb>As>Cu>Zn. Nemerow index and comprehensive pollution index value stipulated an insignificant to moderate pollution by the studied elements. Consequently, no ecological risk was posed via elements studied in the proposed sites. The emerging sources for PTEs are confined to both anthropogenic and lithogenic derivations. Non-carcinogenic risk assessment stipulated that the river water was safe for adults and children as the estimated Hazard Quotient (HQ) and Hazard Index (HI) value was found below the threshold value (HQ/HI<1). Total carcinogenic risk was calculated at 7.44E−08 and 1.60E−08 for adults and children, respectively, specifying no risk, and water from the sites was evaluated as suitable for agricultural irrigation purposes on the basis of estimated indices.

Assessment of potability of surface water and its health implication in Mahanadi Basin, Odisha

Surface water resource plays a crucial role in economic development, human health, and ecological diversity. Population growth, climate change, and water contamination that result from rising residential, agricultural, and industrial needs have put a great deal of strain on the Mahanadi River in Odisha. The study was conducted to analyse surface water quality fluctuations using monitoring data of 20 water quality indicators at 19 locations during 2012–2022. The proposed work includes Weighted Arithmetic (WA) Water Quality Index (WQI), Canadian Council of Ministers of the Environment (CCME) WQI, Synthetic Pollution Index (SPI), Numerow's Pollution Index (NPI), Overall Index of Pollution (OIP), Comprehensive Pollution Index (CPI), Eutrophication Index (EI), Organic Pollution Index (OPI) and multivariate techniques like Cluster analysis (CA) and Principal Component Analysis (PCA) to analyse surface water quality. The results showed that the surface water was contaminated with high TC and TKN. The WQIs results demonstrated that the categories of excellent, good, poor, extremely poor, and unsuitable water quality that fluctuated at the chosen sampling points. Most of the locations fell into the excellent to good zone, as determined by the WQIs and Pollution indexes (PIs). According to several indexing methods, the results show that WA WQI (15.79%), CCME WQI (10.53%), SPI (15.79%), NPI (15.79%), OIP (15.79%), and CPI (15.79%) of the samples had poor, extremely poor, or unsuitable drinking water quality. The watercourse was highly susceptible to eutrophication at few locations as EI was above zero. Three locations (sites 8, 9 and 19) at the downstream of the river are polluted with organic substances with OPI > 1. To examine the link between the water quality measures, the correlation matrix has been developed. To find out the commonalities in the features of the water quality, hierarchical CA divided the 19 monitoring sites into three groups. Five principal components (PCs), which together account for 93.91% of the total variance, were identified via PCA. The first PC was devoted to mineralization, whereas the remaining PCs were constructed using characteristics that suggested contamination. To investigate the spatial distribution, the spatial analyst tools (IDW method) were used. Combining results with GIS also allows for a deeper analysis of drinking water quality. Ultimately, the combined use of various water quality indices along with GIS, CA, and PCA results in the conclusion that samples from the locations ST-8, ST-9 and ST-19 are the most prevalent and fall into the poor to extremely poor group. Considering the entire study, it was determined that the polluting factors were the fertilizers, land development, storm water runoff, and domestic waste water discharge. It is recommended that the sources of contaminations can be further explored to reduce the pollution load, that might be helpful in the promotion of sustainable ecotourism.

Synergies of green policies and their pollution reduction effects: Quantitative analysis of China's green policy texts

Synergy is an important step to enhance policy effectiveness and has been discussed in many fields. In order to promote the transformation and upgrading of polluting industries, green policy synergy is urgent to be studied comprehensively. Thus, this paper analyzes the temporal evolution laws of policy content synergy, policy department synergy, and policy type synergy, and further investigates the pollution reduction effect of policy synergy according to the green policy texts issued by Chinese ministries and commissions from 2001 to 2021. The results are as follows. (1) Policy content synergy significantly suppresses the emission intensity of various pollutants. The pollution reduction effect is proportional to the content synergy degree of policies. (2) The policy department synergy significantly reduces the emission intensity of sulfur dioxide, solid waste, and comprehensive pollution, but the suppression effect on chemical oxygen demand and ammonia nitrogen oxygen demand is not obvious. (3) The pollution reduction effect varies with the policy type synergy. Specifically, the synergistic pollution reduction effect of command and control, market incentive, and public participation policies is the best, followed by market incentive and public participation policies, and that of command and control and market incentive policies is the worst. (4) Further research shows that energy consumption significantly negatively regulates the pollution reduction of the policy content synergy and the policy type synergy, but not the policy department synergy. Meanwhile, adjusting industrial structure can promote pollution reduction. This study provides an important reference for enhancing the synergy among green policies and achieving the goal of carbon peak and carbon neutrality.

Characteristics and Risk Assessment of PAH Pollution in Soil of a Retired Coking Wastewater Treatment Plant in Taiyuan, Northern China.

We analyzed the soil at the site of a former coking wastewater treatment plant on redeveloped land in Taiyuan, northern China, in an attempt to detect the presence of 16 types of priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency (US EPA) and evaluate the potential pollution risks. The results show that the total proportion of PAHs in the surface soil of the redeveloped land ranged from 0.3 to 1092.57 mg/kg, with an average value of 218.5 mg/kg, mainly consisting of high-ring (5-6 rings) components. Characteristic ratio analysis indicated that the pollution was mainly related to the combustion of petroleum, coal, and biomasses. The wastewater treatment units operated according to the following treatment train: advection oil separation tank, dissolved air flotation tank, aerobic tank, secondary sedimentation tank, and sludge concentration tank. Our study found that pollution resulting from low-ring PAHs mainly appeared in the advection oil separation tank during the pre-wastewater treatment stage, while medium-ring PAH contamination mainly occurred in the dissolved air floatation tank, aerobic tank, and secondary sedimentation tank during the middle stages of wastewater treatment. High-ring PAH contamination primarily appeared in the sludge concentration tank in the latter stage of wastewater treatment. Based on our assessment of the ecological risk using the Nemerow Comprehensive Pollution Index and the toxicity equivalent factor (TEF) method, we determined that individual PAHs in the study area exceeded acceptable levels and the total amount of pollution was potentially harmful to the ecological environment. In addition, the comprehensive lifetime cancer risk for different populations resulting from exposure to the soil in the study area was determined to be within acceptable limits based on the average PAH concentrations.

Water quality assessment of deep learning-improved comprehensive pollution index: a case study of Dagu River, Jiaozhou Bay, China

In the past few decades, with the country's rapid development, water pollution has become a significant problem many countries face. Most of the existing water quality evaluation uses a single time-invariant model to simulate the evolution process, which cannot directly describe the complex behavior of long-term water quality evolution. In addition, the traditional comprehensive index method, fuzzy comprehensive evaluation, and gray pattern recognition have more subjective factors. It can lead to an inevitable subjectivity of the results and weak applicability. Given these shortcomings, this paper proposes a deep learning-improved comprehensive pollution index method to predict future water quality development. As a first processing step, the historical data is normalized. Three deep learning models, multilayer perceptron (MLP), recurrent neural network (RNN), and long short-term memory (LSTM), are used to train historical data. The optimal data prediction model is selected through simulation and comparative analysis of relevant measured data, and the improved entropy weight comprehensive pollution index method is applied to evaluate future water quality changes. Compared with the traditional time-invariant evaluation model, the feature of this model is that it can effectively reflect the development of water quality in the future. Moreover, the entropy weight method is introduced to balance the errors caused by subjective weight. The result shows that LSTM performs well in accurately identifying and predicting water quality. And the deep learning-improved comprehensive pollution index method can provide helpful information and enlightenment for water quality change, which can help improve the water quality prediction and scientific management of coastal water resources.

Identifying the critical areas and primary sources for agricultural non-point source pollution management of an emigrant town within the Three Gorges reservoir area

Agricultural non-point source pollution is threatening water environmental health of the Three Gorges reservoir. However, current studies for precision management of the agricultural non-point source pollution within this area are still limited. The objective of this study was identifying the critical areas and primary sources of agricultural non-point source pollution for precision management. Firstly, the inventory analysis approach was used to estimate the discharge amount of total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) from farmland fertilizer, crop residues, livestock breeding, and daily activities. Afterwards, the deviation standardization method was applied to evaluate the emission intensity of TN, TP, and COD, as well as calculating the comprehensive pollution index (CPI) of each village, based on which the critical areas for agricultural non-point source pollution management could be distinguished. Moreover, the equivalence pollution load method was conducted to identify the primary pollution sources within each critical zone. The above methods were implemented to an emigrant town within the Three Gorges reservoir area named Gufu. Results showed that agricultural non-point source pollution in Gufu town has been alleviated to a certain extent since 2016. Nevertheless, in four areas of the town (i.e., Longzhu, Fuzi, Shendu, and Maicang), the agricultural non-point source pollution still deserved attention and improvement. For the mentioned critical areas, farmland fertilizer and livestock breeding were the primary sources causing agricultural non-point source pollution. The emission amount of TN and TP from farmland fertilizer accounted for 60% and 48% of the total, respectively. And those from livestock breeding were 29% and 46%. Our research could provide definite targets to relieve agricultural non-point source pollution, which had great significance to protect water environment while coordinating regional economic growth after emigrant resettlement.

Ecological and human health hazards; integrated risk assessment of organochlorine pesticides (OCPs) from the Chenab River, Pakistan

Carcinogenic hazards to human health were investigated through oral and dermal exposure to organochlorine pesticides (OCPs) from water samples (n = 120) of River Chenab, Pakistan. The Pioneering study aimed to employ an integrated geographic information system (GIS) based geostatistical method for the determination of pollution load by GC-ECD from water of River Chenab. The residual levels of OCPs detected from water samples ranged from 0.54 to 122 ng L−1 with significant prevalence of DDE and α-HCH. Results of the Nemerrow pollution index (NeI), single pollution index (SPI), and comprehensive pollution index (CPI) reflected the downstream zone a stern pollution risk zone. The spatial distribution pattern through geostatistical approaches also revealed significantly higher (p < 0.05) OCP levels in the downstream zone. Risk quotient (RQCCC) of surface water quality with respect to heptachlor epitomized a high level of risk (RQCCC > 1). Non-carcinogenic human health risk (Σ HQ) assessment ranged from 8.39 × 10−9 to 1.7 × 10−3, which represented a marginal risk through oral and dermal exposure. However, carcinogenic risks by oral exposure route were ranged from 3.57 × 10−11 to 4.46 × 10−6. Estimated cancer risk (ΣCR) exhibited a considerable carcinogenic risk posed by heptachlor, α-HCH and dieldrin. It is suggested to employ an immediate mitigation strategy for the constant discharge of OCPs in the studied area.

Toxic Metal Concentrations and Exposure Risks Associated with Surface Water, Seafood (Clarias gariepinus, Oreochromis niloticus, Cottus gobio) and Vegetable (Telfairia occidentalis) from Elebele River, Nigeria

Human exposure to elevated levels of environmental contaminants is an important concern of health toxicology. This study assessed the toxicity level of toxic metals including Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Lead (Pb) and Nickel (Ni) in samples of water, seafood (Clarias gariepinus, Oreochromis niloticus, Cottus gobio) and vegetable (Telfairia occidentalis) from the adjacent area of Elebele River, Nigeria, bioconcentration and toxic metal exposure posed to communities consuming these foodstuffs. The following indices: single-factor index and the comprehensive pollution index, metal pollution index, estimated daily and weekly intakes, hazard index and lifetime cancer risk were applied. Samples of water, seafood and vegetable were analysed using Atomic Absorption Spectrophotometer. The results showed that the concentrations of metals except for Cd in water samples were higher than the permissible limits by international organisations. Results also revealed that the concentrations of metals in foodstuff samples were within limits. Furthermore, the values of estimated weekly intakes calculated were lower than the limits of provisional tolerable weekly intakes established by the Food and Agriculture Organization and World Health Organization. This suggests no health risks and is consistent with the HI results. However, As was a major contributor (96.9%) to health risks associated with the ingestion of water. Lifelong consumption of T. occidentalis might be hazardous in the study locality. The carcinogenic risk was &gt; 1 × 10‒4 for As and Ni. Therefore, to reduce the health risk and the extent of metal contamination, steps must be taken for the efficient removal of metals from the water body.

Pollution Risk and Contribution Analysis of Pb, Cd, and As in Soils and Crops Under Different Land Use Types in Longyan City

A total of 174 soil samples and 87 grain samples were collected in two typical fields in Longyan City. The pollution index method, Hakanson potential ecological risk index method, and EPA human exposure risk assessment model were used to evaluate the pollution status, ecological risk, and health risks of heavy metals Pb, Cd, and As in soil of different land use types. The contributions of Pb, Cd, and As to soil and crop pollution risk were also analyzed. The results indicated that the pollution levels of Pb, Cd, and As in soils and crops of different utilization types in regionⅠwere low. Cd was the main soil pollutant and ecological risk factor, contributing 55.3% to comprehensive soil pollution and 60.2% to comprehensive potential ecological risk, respectively. The pollution levels of Pb, Cd, and As in soils and crops in regionⅡwere high. Pb and Cd were the main soil pollutants and ecological risk factors, contributing 44.2% and 51.6% to comprehensive pollution and 23.7% and 67.3% to comprehensive potential ecological risk, respectively. Pb was the main pollution factor of crops, contributing 60.6% and 51.7% to the comprehensive pollution of coix and rice, respectively. The carcinogenic risks of Cd and As in soil of the two typical regions for adults and children were all within the acceptable range under the oral-soil exposure pathway. The contribution of Pb, Cd, and As to the total non-carcinogenic risk in regionⅠwas Pb (68.1%)>As (30.5%)>Cd (1.38%). There was no carcinogenic risk of Pb in rice in the two typical regions under the oral-rice intake pathway. The contribution of Cd and As to carcinogenic risk in adults and children were As (76.8%)>Cd (22.7%) and Cd (69.1%)>As (30.3%), respectively. Three pollutants in regionⅠand Ⅱ had high non-carcinogenic risk, and As was the most significant contributor (84.0% and 52.0%, respectively), followed by Cd and Pb.