Environmental Quality Standards Research Articles

Developing As and Cu Tissue Residue Thresholds to Attain the Good Ecological Status of Rivers in Mining Areas

The study was performed on residue-effects datasets from polluted and unpolluted sites in the Nalón River basin (northern Spain). The effects were measured in terms of alteration of field macroinvertebrate communities, and measured as ecological status scores, and number of families and abundance of Ephemeroptera, Plecoptera and Trichoptera (EPT). Non-linear regression models of the field-measured tissue residues in 10 taxa related to the ecological status of the macroinvertebrate communities were used to derive effective tissue residues (ERs). These were estimated for the good/moderate boundary defined by the ecological quality ratio (EQRs) score and for the 50% reduction of EQR and EPT metrics. As, Cu, Hg and Se ERs were calculated for several macroinvertebrate taxa with different feeding styles. The ER dataset allowed us to estimate As and Cu hazardous concentrations (HC), using species sensitivity distribution models, and were interpreted as community thresholds. Further studies for Hg and Se are needed to complete the database required for HC estimation. The reliability and differences of the several thresholds were tested in a risk assessment using a tissue-residue approach (TRA) conducted with field organisms from Cauxa Creek, a tributary from the same basin exposed to high levels of metals in the sediments due to gold mining activities. This risk assessment identified that As and Cu tissue residues satisfactorily explained the reduction in the ecological status of the macroinvertebrate assemblages. Our results indicate that TRA can help in setting future environmental quality standards for the protection of aquatic biota.Graphical

Penentuan Status Mutu Air Tukad Mati Dari Kuta Utara Hingga Kuta Selatan Berdasarkan Metode Indeks Pencemaran

This study discusses the water quality of Tukad Mati which occupies the area of Badung Regency in the upstream and downstream parts that stretch from North Kuta to South Kuta while the middle part crosses Denpasar City in terms of physical, chemical, and biological parameters and classifies the water quality of Tukad Mati with the Pollution Index method. The purpose of this study was to determine the quality of Tukad Mati water in terms of several parameters such as temperature, dissolved residue, suspended solids, pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), phosphate, fecal coliform, and total coliform. The results of the measurement of water samples are compared with environmental quality standards and environmental damage standard criteria based on Bali Governor Regulation No. 16 of 2016. The results of the analysis show that there are several parameters whose values exceed the threshold of class II water quality standards, namely TSS, BOD, and phosphate. The result of the Tukad Mati Pollution Index value in the upstream area has a value of 4.86 in the middle has a value of 3.02 and downstream has a value of 3.48 which is categorized as lightly polluted.

Assessing Nickel Risks in Freshwater to Deliver Better Environmental Protection.

Routine regulatory assessment of aquatic risks relies upon the development of an appropriately robust and reliable metric of the hazards of a substance. This may be in the form of a water quality guideline or environmental quality standard (EQS), with a practical methodology to consistently use and implement these metrics. Both the EQS itself and an implementation strategy are needed to deliver better environmental protection. This article is protected by copyright. All rights reserved.

Littoral macrobenthic communities and water quality in El Pañe Reservoir, Arequipa, Peru

ABSTRACT High Andean ponds and reservoirs are among the least-studied environments. We evaluated the composition of littoral macrobenthos and how it is affected by the physicochemical conditions of the water in El Pañe reservoir (Peru), located at 4,550 m.a.s.l. Samples were taken between November 2017 and October 2018 from three zones in the reservoir: low (downstream), middle and high (upstream); two of these zones with fish farms (low and middle) and one zone without fish farms (high). The following physicochemical parameters of the water were measured: dissolved oxygen, conductivity, pH and temperature. The macrobenthic community was analysed through diversity indices such as Shannon-Wiener (H’), Simpson’s dominance index (D), Pielou’s evenness (J’), true diversity (D1), and richness (S). The influence of the physicochemical variables on the macrobenthos was estimated by canonical correspondence analysis (CCA) and non-metric multidimensional scaling (NMDS). Dissolved oxygen was found to have lower values (<0.5 mg/l) than specified in the Environmental Quality Standards (EQS). Macroinvertebrate richness for the whole reservoir was 17 families, and the family with highest relative abundance was Chironomidae (42.24% in the low zone, 51% in the middle zone and 40.43% in the high zone). The indices showed greater species richness in the high zone, where there are no fish farms. Dissolved oxygen and conductivity were the main factors determining macrobenthos distribution and composition.

Treatment of Sugarcane Industry Waste Water by Combination of Chemical Coagulation and Activated Carbon

The study was designed to treat the effluent from sugarcane sector. The use of fresh water in sugarcane industry and result huge amount of waste water is not a secret to anyone. The use of chemicals in large quantities has caused a great risk and damage to the groundwater, soil, and aquaculture and ultimately leads to the destruction of our environment. Treatment of industrial sugarcane wastewater is not an easy task it has becomes a challenging task for environmental scientist. The purpose of our study is treatment, time saving and reuse for irrigation purpose. Coagulation with alum, ferric chloride, ferrous sulphate with combination of activated charcoal technique was used. The results of the study disclosed that COD and BOD were in huge amount and were successfully treated. Results of COD and BOD removal efficiencies were 51 and 28 mg/L, 76 and 42 mg/L, 90 and 52 mg/L by using alum, ferric chloride and ferrous sulphate respectively with combination of activated charcoal. After treatment, the effluent was very clear and met the requirements of National Environmental Quality Standards. Subsequently, using coagulation with combination of adsorption technique proved very effective, time saving, harmless technique for industrial sugarcane wastewater treatment.&#x0D;

Arsenic Accumulation and Physiological Response of Three Leafy Vegetable Varieties to As Stress.

Arsenic (As) in leafy vegetables may harm humans. Herein, we assessed As accumulation in leafy vegetables and the associated physiological resistance mechanisms using soil pot and hydroponic experiments. Garland chrysanthemum (Chrysanthemum coronarium L.), spinach (Spinacia oleracea L.), and lettuce (Lactuca sativa L.) were tested, and the soil As safety threshold values of the tested leafy vegetables were 91.7, 76.2, and 80.7 mg kg−1, respectively, i.e., higher than the soil environmental quality standard of China. According to growth indicators and oxidative stress markers (malondialdehyde, the ratio of reduced glutathione to oxidized glutathione, and soluble protein), the order of As tolerance was: GC > SP > LE. The high tolerance of GC was due to the low transport factor of As from the roots to the shoots; the high activity of superoxide dismutase, glutathione peroxidase, and catalase; and the high content of phytochelatin in the roots. Results of this work shed light on the use of As-contaminated soils and plant tolerance of As stress.

Chromium contamination in paddy soil-rice systems and associated human health risks in Pakistan

Chromium (Cr) contamination in paddy soil-rice systems threatens human health through the food chain. This study used a new dataset of 500 paddy soil and plant tissue samples collected in the rice-growing regions of Sindh and Punjab Provinces of Pakistan. Overall, 97.4% of grain samples exceeded the Cr threshold values of 1.0 mg kg−1, determined by the China National Food Standard (CNFS). The Cr in paddy soil, 62.6% samples exceeding the China natural background threshold value (90 mg kg−1) for Cr concentration in paddy soil, and lower than the (pH-dependant > 7.5 threshold value for Cr 350 mg kg−1) as determined by China Environmental Quality Standards (EQSs) for paddy soil (GB15618-2018). Geographically weighted regression (GWR) modelling showed spatially nonstationary correlations, confirming the heterogeneous relationship between dependent (rice grain Cr) and independent paddy soil (pH, SOM, and paddy soil Cr) and plant tissue variables (shoot Cr and root Cr) throughout the study area. The GWR model was then used to determine the critical threshold (CT) for the measured Cr concentrations in the paddy soil system. Overall, 38.4% of paddy soil samples exceeding CT values confirm that the paddy soil Cr risk prevails in the study area. Furthermore, the GWR model was applied to assess the loading capacity (LC), the difference between the CT, and the actual concentration of Cr in paddy soil. Loading capacity identified potential paddy soil Cr pollution risk to rice grain and assessed the risk areas. Overall LC% of samples paddy soil Cr risk areas grade: low-risk grade I (34.6%); moderate-risk grade II (15.8%); high-risk grade III (11.2%); and very high-risk grade IV (38.4%) have been assessed in the study area.The human health index, total hazard quotient (THQ ≪ 1), indicates no potential health risk originating from Cr exposure to the population. However, the excess Cr level in paddy soil and rice grain is still a concern. The current study's results are also valuable for the national decision-making process regarding Cr contamination in the paddy soil-rice system.

Development and application of an innovative approach to predicting pollutant concentrations in highway runoff

Recognising the challenges and limitations of current methodologies to predict highway runoff concentrations, this paper presents a novel approach based on the derivation of pollutant emission factors for twelve different types of vehicle. Published emission factor data and properties of differing vehicles types are combined with annual average daily traffic volume (AADT), highway characteristics and rainfall data to determine the pollutant distributions associated with differing highway and traffic types. In this paper, the method is applied to 126 sections of highway in the Greater London Borough of Enfield (United Kingdom; UK) and results are comparable with values reported in the literature. The approach is used to identify the level of AADT predicted to result in an exceedance of environmental quality standards (EQS), with results suggesting that runoff from highways experiencing AADT values as low as 5000 may require treatment prior to discharge to receiving waters. Future scenario analyses indicate that the impact of progressively replacing petrol and diesel vehicles with electric vehicles will have negligible impact on concentrations of zinc (Zn), copper (Cu), cadmium (Cd) and total suspended solids discharging from highway environments. The approach enables identification and ranking of urban highways in terms of their pollution runoff potential and provides an important support to users in prioritising locations for the installation of sustainable drainage options in order to protect receiving water environments.

Twenty years of China's water pollution control: Experiences and challenges

Water pollution is a major environmental problem worldwide, especially in developing countries. China's environmental protection strategies have been pushed to the highest priority in history, driving remarkable achievements in water pollution control, but were also coupled with new challenges. In this study, we analyzed diverse long-term data (i.e. water quality, WWTPs, pollutant discharge etc.) to systematically understand the process of water pollution control in China in the last twenty years. The results highlighted that the collection and treatment capacity of wastewater in China approached the developed country level, with the treatment rates exceeding 90% both in urban and country areas. The environmental quality of surface water was continuously improved, but water pollution problems remained in the river basins of eastern China, with remarkable economic progress. Rapid economic growth rather than population growth was the limiting factor for water pollution control in China. Therefore, more efforts should be made to further improve wastewater collection and treatment capacity and address the gap between effluent discharge limits for wastewater treatment plants and environmental quality standards for surface water. China's progress toward water pollution control provided important insights for other developing countries.

Distribution of organochlorine pesticides and polychlorinated biphenyls present in surface sediments of the Sabaki and Tana estuaries, Kenya

Polychlorinated biphenyls (PCBs) and Organochlorine pesticides (OCPs) in the surface sediments of the Sabaki and Tana estuaries were studied to determine distribution as well as their ecological risk. The concentration range of PCBs and OCPs were 0.65-9.29 ng/g dw and 0.47-9.84 ng/g dw, respectively. Sabaki Bridge in the Sabaki River and Tana 4 in the Tana River recorded high levels of both PCBs and OCPs. The calculated values of DDD+DDE/ DDT showed that the presence of DDT from both the rivers is a result of historical input. The ecotoxicological impact of sediment pollution by PCBs and OCPs was assessed using sediment quality guidelines specified by the Canadian Council of Ministers of the Environment. The concentration values for PCB, HCB, Heptachlor epoxide, and Chlordane in this study indicate low ecological risk to sediment dwelling organisms. DDT showed an adverse biological effect to sediment dwelling organisms. As a result, there is a need to establish a programme for monitoring persistent organic pollutants in Kenya, so that any elevation in concentration above the environmental quality standards can be detected and appropriate actions taken to minimize potential adverse effects to the environment and public health.

INCIDENCE OF HEAVY METALS IN WATER, SOIL, ALFALFA (MEDICAGO SATIVA L.) AND SHEEP (OVIS ARIES L.) ALONG THE QUILCA - VITOR - CHILI BASIN IN AREQUIPA, PERU

The concentration of heavy metals (Cd, Cu, Cr, Fe, Hg, Pb, Zn) and arsenic was determined in water, soil and alfalfa samples in three sites (Congata, Uchumayo and Vitor) located along the Quilca - Vitor - Chili River, near the city of Arequipa, Peru. The content of these elements was also analysed in samples of alfalfa at different times of being planted (1 to 3 months) in Congata. Alfalfa planted in three other locations (Quiscos, Yarabamba and La Joya) upstream and downstream of the first three was also analysed. To determine the concentration of heavy metals in sheep, measurements were made on liver and kidney samples from animals farmed in the first three sites. The concentration of metals and arsenic in the water samples was lower than the Peruvian environmental quality standards, except for Hg in Vitor (0.0001 mg L-1). The Cd content in the soil at all three sites (62.01 - 381.94 mg kg-1) was well above the EQS for agricultural, commercial or industrial soils. The Cd content in the alfalfa samples grown in the same soils was higher than that observed in the samples from Quiscos, Yarabamba and La Joya. The estimated daily intake values (EDI) for metals detected in sheep kidneys and liver (Fe, Cu, Zn) were below the provisional maximum tolerable daily intakes (PMTDI) for children and adults, while the target hazard quotient (THQ) and total THQ of these elements were less than 1, indicating that their consumption would not have an adverse health effect.

BONGGOL JAGUNG DAN KULIT PISANG RAJA (Musa Paradisiaca) EFEKTIF SEBAGAI ADSORBEN Fe DALAM AIR SUMUR

Well water in Kedung Sekar village which contains high levels of iron (Fe) can cause economic losses such as clogged pipes, yellow clothes and skin irritation. Utilization of waste corn cobs and Musa Paradisiaca peels as activated carbon can reduce Fe levels in water. The purpose of this study was to compare the effectiveness of activated carbon made from corn cobs and Musa Paradisiaca peels to reduce Fe content in water. This type of research is pre-experimental. Examination of Fe levels in the laboratory to determine the content before and after treatment. Treatment using a variety of doses of activated carbon 4 g, 6 g, 8 g. Data analysis used a statistical test, namely One Way Anova and compared it with the Minister of Health Regulation Number 32 of 2017 concerning Environmental Quality Standards and Water Health Requirements for Sanitary Hygiene Needs. The results showed that there was a decrease in Fe levels at a dose of 8 g for corn cobs activated carbon by an average of 0.95 mg/l or 94.36% and for Musa Paradisiaca peels activated carbon there was a decrease at a dose of 8 g of 1.56 mg/l or 90.74%. Statistical testing obtained the value of Sig. 0.000, which means that there is a difference in the decrease in iron (Fe) levels after adsorption with activated carbon from corn cobs and Musa Paradisiaca peels. The conclusion that can be formulated is that activated carbon from corn cobs and Musa Paradisiaca peels can reduce iron (Fe) levels in water. Suggestions for other researchers can use variations of activator KOH, CaCl2, NaOH to make activated carbon and check the quality of charcoal according to SNI 06-3730-1995.

Polar organic chemical integrative samplers as an effective tool for chemical monitoring of surface waters – Results from one-year monitoring in France

In an effort to support European Union Water Framework Directive goals, we have set up a national demonstrator project to identify the advantages and limitations of passive samplers for regulatory monitoring of polar contaminants in surface waters. Here we carried out successive 14 day-deployments of polar organic chemical integrative samplers (POCIS) for one year at three sites. In parallel, we used the passive sampler deployment/retrieval operations to collect spot water samples for comparative analysis. We observed that frequency of quantification was significantly higher in POCIS than spot samples for 29 contaminants, similar for 15, and lower for one, because POCIS lowered the limits of quantification for most contaminants (median value factor of 11). We built a database of sampling rates (Rs) according to quality indices to convert concentrations in POCIS to concentrations in water (23 contaminants with a high-quality median Rs value, 20 with an approximate Rs and two with no usable Rs). Several phenomena were observed over one-year monitoring period. For example, after a flood episode, dilution phenomenon in rivers is correctly observed by using POCIS sampling whereas significant concentration increased due to soil leaching is observed with both passive and spot sampling. Cases of episodic contamination that were missed by spot sampling were observed with POCIS as it was able to capture contamination of short duration but sufficient intensity. Contamination by pharmaceuticals was found to come from wastewater treatment plant discharges and showed relatively little variation over the course of the year in both POCIS and spot samples. POCIS enables more reliable annual monitoring of pesticide and pharmaceutical contamination than spot sampling. Furthermore, POCIS also improves the environmental quality standards based assessment of chemical status and on annual average concentrations compared to spot sampling. This study demonstrates the value and practicability of POCIS-based chemical monitoring for use in regulatory control networks.

Trends and Causes of Raw Water Quality Indicators in the Five Most Famous Lakes of Jiangsu Province, China.

Due to pollutants from industrial and agricultural activities, the lakes in China are faced with ecological and environmental problems. The five most famous lakes of Jiangsu Province, Taihu Lake, Gehu Lake, Gaobaoshaobo Lake, Hongze Lake, and Luoma Lake, have long-term fixed monitoring points for water body-related indicators. Over a five-year period, the monitoring showed that Gehu Lake had the highest average total nitrogen (TN) and total phosphorus (TP) concentrations among all lakes which were close to the Grade V critical value of the China’s Environmental Quality Standards for Surface Water (CEQSW). The NH3-N concentrations in all lakes were Grade IV according to the China’s Water Quality Standard for Drinking Water Sources (CWQSDWS) and Grade II according to the CEQSW. In addition, although TP concentrations in Taihu Lake did not exceed Grade V in the CEQSW, TP removal was the main factor controlling eutrophication. It was also found that the petroleum concentrations in all lakes were lower than the Grade I according to the CEQSW. Despite this relatively low petroleum pollution, the concentration of petroleum was negatively correlated with the phytoplankton densities in all lakes. This indicated that phytoplankton density was very sensitive to petroleum concentration. For heavy metals, the concentrations of Pb, Cu, As, and Cd in all lakes were significantly lower than Grade I (CEQSW) from 2013 to 2017. However, the accumulated heavy metals in sediments will remain an important pollution source affecting water quality and aquatic products in the future. The comprehensive pollution index analysis showed that the five lakes were often moderately polluted, indicating that the protection of lake resources in China should not be relaxed for a long time in the future.

Effectiveness of Exogenous Fe2+ on Nutrient Removal in Gravel-Based Constructed Wetlands.

A group of microcosm-scale unplanted constructed wetlands (CWs) were established to evaluate the effectiveness of exogenous Fe2+ addition on ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), and total phosphorus (TP) removal. The addition of Fe2+ concentrations were 5 mg/L (CW-Fe5), 10 mg/L (CW-Fe10), 20 mg/L (CW-Fe20), 30 mg/L (CW-Fe30), and 0 mg/L (CW-CK). The microbial community in CWs was also analyzed to reveal the enhancement mechanism of pollutant removal. The results showed that the addition of Fe2+ could significantly (p < 0.05) reduce the NO3−-N concentration in the CWs. When 10 mg/L Fe2+ was added and the hydraulic retention time (HRT) was 8 h, the highest removal rate of NO3−-N was 88.66%. For NH4+-N, when the HRT was 8–24 h, the removal rate of CW-Fe5 was the highest (35.23% at 8 h and 59.24% at 24 h). When the HRT was 48–72 h, the removal rate of NH4+-N in CWs with 10 mg/L Fe2+ addition was the highest (85.19% at 48 h and 88.66% and 72 h). The removal rate of TP in all CWs was higher than 57.06%, compared with CW-CK, it increased 0.63–31.62% in CWs with Fe2+ addition; the final effluent TP concentration in CW-Fe5 (0.13 mg/L) and CW-Fe10 (0.16 mg/L) met the class III water standards in Surface Water Environmental Quality Standards of China (GB3838-2002). Microbical diversity indexes, including Shannon and Chao1, were significantly lower (p < 0.05) in Fe2+ amended treatment than that in CW-CK treatment. Furthermore, phylum Firmicutes, family Carnobacteriaceae, and genus Trichococcus in Fe2+ amended treatments was significantly (p < 0.05) higher than that in CW-CK treatment. Fe3+ reducing bacteria, such as Trichococcus genus, belonging to the Carnobacteriaceae in family-level, and Lactobacillales order affiliated to Firmicutes in the phylum-level, can reduce the oxidized Fe3+ to Fe2+ and continue to provide electrons for nitrate. It is recommended to consider adding an appropriate amount of iron into the water to strengthen its purifying capacity effect for constructed artificial wetlands in the future.

Water quality analysis of old and new Phuleli Canal for irrigation purpose in the vicinity of Hyderabad, Pakistan

Abstract Irrigation-water quality plays an important role in agriculture productivity. In this study, water quality of the old and new Phuleli canal located in Hyderabad, Pakistan, was characterized for irrigation purpose. Water samples were collected from four different locations of both the old and new Phuleli canal. Twelve different irrigation-water quality standards were assessed under the study: pH, Electricity Conductivity, Biochemical Oxygen Demand (BOD), Total Dissolved Solids, Chemical Oxygen Demand (COD), Dissolved Oxygen, Calcium, Magnesium, Sodium, Potassium, Sodium adsorption ratio, Fecal Coliforms. The results showed that the Electricity Conductivity ranges from 910–3,090 MS/cm, Potassium 13–112 mg/l, BOD 61–285 mg/l, COD 97–361 mg/l and Fecal Coliforms 400–2,350 MPN/100 ml concentrations in water of both canals were higher than the National Environmental Quality Standards permissible limits. It was found that the water quality parameters were higher than the permissible pollution level of canal water for the use of irrigation in agriculture.

Ibuprofen exposure in Europe; ePiE as an alternative to costly environmental monitoring

The EU Water Framework Directive and Priority Substance Directive provide a framework to identify substances that potentially pose a risk to surface waters and provide a legal basis whereby member states are required to monitor and comply with environmental quality standards (EQSs) set for those substances. The cost and effort to continuously measure and analyse real world concentrations in all water bodies across Europe are high. Establishing the reliability of environmental exposure models to predict concentrations of priority substances is key, both to fill data gaps left by monitoring campaigns, and to predict the outcomes of actions that might be taken to reduce exposure. In this study, we aimed to validate the ePiE model for the pharmaceutical ibuprofen by comparing predictions made using the best possible consumption data with measured river concentrations. The results demonstrate that the ePiE model makes useful, conservative exposure predictions for ibuprofen, typically within a factor of 3 of mean measured values. This exercise was performed across a number of basins within Europe, representative of varying conditions, including consumption rates, population densities and climates. Incorporating specific information pertaining to the basin or country being assessed, such as custom WWTP removal rates, was found to improve the realism and accuracy of predictions. We found that the extrapolation of consumption data between countries should be kept to a minimum when modelling the exposure of pharmaceuticals, with the per capita consumption of ibuprofen varying by nearly a factor of 10.

Mercury (Hg) and methylmercury (MeHg) in sediment and biota: A case study in a lagoon in Central Italy

A quantification of total mercury (Hgtot) and methylmercury (MeHg) concentrations in sediment and mussels was carried out in the east basin of the Orbetello lagoon in order to assess their bioaccumulation potential. The sediment was sampled in four macroareas, mussels were transplanted in the same sites and collected after seven weeks. The results show that Hgtot concentrations in sediments exceeded (0.21–16.9 mg/kg dry weight (dw)) the environmental quality standard of the Italian legislation (0.3 mg/kg dw). The Hgtot concentration in mussels (0.050–0.324 mg/kg wet weight (ww)) does not exceed the limit values (0.5 mg/kg ww) of the European food legislation. The biota–sediment accumulation factors (BSAFs) derived for MeHg (80–306.7) and a biomagnification factor (BMF) greater than 1 for Hgtot demonstrate that in the lagoon, these compounds can be transferred in the upper levels of the trophic chain and pose a risk to human health.

Spatial and temporal variability and sources of dissolved trace elements in the Sava River (Slovenia, Croatia).

The spatial and temporal variability of dissolved trace elements (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Sb, Sr, Ti, U, V and Zn) in the upper and middle reaches of the Sava River during two campaigns (2007/2008 and 2017/2018) was examined. The study also included important tributaries and wastewater effluents. No crucial change in metal concentrations in the Sava River water between the two sampling periods was detected. Elements Co, Cr, Cu, Fe, Sb and Zn had higher concentrations at several sites in the first period, whereas Ba, Cd and Pb in the second period. The influence of wastewater discharges proved to be negligible. The highest levels of potentially toxic metals (Cd, Cr, Cu, Sb, V and Zn) were found downstream of the industrial town of Sisak. Concentration-discharge relationship of dissolved elements showed a chemostatic behaviour for As, Cr, Cu, Sr and V and chemodynamic behaviour for all other elements. The UNMIX model, used to identify and quantify metal sources, indicated that soil weathering was the main source of most elements (Al, As, Ba, Co, Cu, Fe, Li, Ni, Sb, Sr and V), with an anthropogenic contribution for Cd, Mo, Pb, Ti and Zn, while Mn and U were associated with colloid formation. The Sava River was defined as moderately polluted regarding metals, whose water quality meets environmental quality standards (EQS). These results may help to better understand the behaviour of dissolved metals in rivers under anthropogenic pressure and to control pollution in the Sava River Basin.

Spatial Distribution and Source Analysis of Soil Heavy Metals in a Small Watershed in the Mountainous Area of Southern Ningxia Based on PMF Model

In order to ascertain the distribution characteristics of soil heavy metal pollution and main pollution sources in a small watershed in the southern mountainous area of Ningxia and to ensure the quality of the soil environment, the contents of heavy metals Pb, Ni, Zn, Mn, Cu, Cr, and Cd in 260 surface soil samples (0-20 cm) were collected and determined. Based on the soil background value in Ningxia, the soil heavy metal pollution status and potential ecological risk were evaluated through the single factor index, Nemera composite index, and potential ecological risk index, and the method of combining positive definite matrix factor analysis (PMF) and Kriging interpolation was used to analyze the soil heavy metal spatial distribution and source. The results showed that the average contents of ω(Pb), ω(Ni), ω(Zn), ω(Mn), ω(Cu), ω(Cr), and ω(Cd) were 31.42, 36.22, 62.89, 546.18, 22.26, 61.90, and 0.18 mg·kg-1, respectively. Except for Ni, the other elements were higher than the background value of Ningxia but lower than the background value of agricultural soil pollution risk selection criteria and green food environmental quality standards. The Nemera composite index showed that the proportions of mild, moderate, and severe heavy metal pollution were 71.92%, 19.23%, and 1.54%, respectively. The potential ecological risks were mainly minor risks, accounting for 98.85%. In addition, there were a very small number of samples with medium potential ecological risk levels, accounting for 1.15% of the total number of samples. Source analysis showed that the main sources of soil heavy metals in the small watershed in the mountainous area of southern Ningxia were mixed sources of fertilization and industrial emissions (12.6%), agricultural activity sources (23.5%), natural parent material sources (27.6%), mixed sources of pesticide use and mining development emissions (17.7%), and atmospheric deposition sources (18.6%).