Trace Element Pollution Research Articles

Assessment of trace element contamination in the historical nesting grounds of green sea turtle (Chelonia mydas) in Hainan Island, China.

Trace element pollution is a potential threat to the reproduction of sea turtles. Hainan Island was previously the most important nesting ground of green sea turtles in China before they disappeared approximately 36 years ago. The Chinese government has encouraged restoration work on historical nesting grounds, and it is necessary to evaluate the status of these sites before conducting habitat restoration. This study analyzed the concentrations of seven trace elements in the surface sediments of 13 historical nesting grounds in Hainan. The average concentrations were 19.47 (Cr), 4.67 (Ni), 6.99 (Cu), 0.08 (Cd), 16.68 (Pb), 0.02 (Hg), and 5.27 (As) mg/kg, which were lower than the first-grade limit values of the GB (18668-2002) national standard in China. The concentrations were close to the background value, except for the relatively high Cd value. The potential ecological risk was ranked as Cd > Hg > As > Cu > Pb > Cr. The spatial distribution of trace element contamination in Hainan was uneven, with high potential ecological risk levels of Cd and Hg contamination in Longwan'gang, Shimeiwan, Yazhou Qu, and Fushicun. Marine mariculture, wastewater discharge, and fishing boats are the main sources of trace element contamination in Hainan. We recommend strengthening the control of Hg and Cd contamination sources, monitoring trace elements in relevant/interest areas, and the environmental protection department should curb local residents from directly discharging mariculture wastewater and domestic sewage into the sea.

Distribution, accumulation, migration and risk assessment of trace elements in peanut-soil system

Trace elements contamination is mainly originated from industrial emission, sewage irrigation and pesticides, and poses a threat to the environment and human health. This study analyzed the trace element pollutants in peanut-soil systems, the enrichment and translocation capacity of peanut to trace elements, and the potential risk of trace elements to environment and human health. The results indicated that Cd and Ni in peanut kernels exceeded the standard limits in 2019, and the exceeding rate were 9% and 31%, respectively. Cd in 8% of soil samples and As in 98% of soil samples exceeded the risk screening value of trace elements. The concentration of trace elements in peanuts was related to varieties and planting regions. In addition, there was a significant positive correlation between the concentration of Cd in peanut kernel and its concentration in soil. Compared with other trace elements, peanut kernels had stronger ability to enrich and transport Cd, Cu, and Zn, the BFs were 0.45, 0.51 and 0.47, respectively. After oil extraction, trace elements were mainly concentrated in peanut meal, and only 0.25% of Cd was in oil. The RI of trace elements was less than 150, indicating that the study area was under low degree of ecological risk. However, As and Cd might pose moderate risk to environment. Trace elements in soil and peanut could not cause non-carcinogenic and carcinogenic risks to human, but the HI and CR value of As (0.59 and 9.54 × 10−5) in soil and CRing value of Cd (9.25 × 10−7) in peanut were close to the critical value. We conclude that Cd pollution in peanut kernel, and Cd and As pollution in soil should be monitored to enter into the food chain or environment and to avoid the possible health hazards and environment risks.

Moss Biomonitoring of Atmospheric Trace Element Pollution in the Republic of Moldova.

The moss biomonitoring technique was used for the assessment of air pollution in the Republic of Moldova, in the framework of the UNECE ICP Vegetation Programme. The content of 11 chemical elements (Al, V, Cr, Fe, Ni, Zn, As, Sb, Cd, Cu, and Pb) was determined by neutron activation analysis and atomic absorption spectrometry in samples collected in spring 2020. Distribution maps were built to identify the most polluted sites. The highest concentrations of elements in mosses were determined in the north-eastern, central, and western parts of the country. The main element associations were identified using factor analysis. Three factors were determined, of which one of mixed geogenic-anthropogenic origin and two of anthropogenic origin. A comparison of the data obtained in 2020 and 2015 showed a significant decrease in the concentrations of Cr, As, Sb, Cd, Pb, and Cu in 2020. The state of the environment was assessed using Contamination Factor and Pollution Load Index values, which characterized it as unpolluted to moderately polluted. Possible air pollution sources in the Republic of Moldova are resuspension of soil particles, agricultural practices, vehicles, industry, and thermal power plants.

Assessment of microplastic and trace element pollution in the southeastern Mediterranean coasts, Egypt, using shellfish Arca noae as a bioindicator

The ubiquitous presence of microplastics (MPs) and trace elements in the marine environment is regarded as a global threat to marine organisms. The current study aims to assess MP levels and trace element (Cu, Zn, Cd, Pb, Se, and Fe) accumulation in the shellfish Arca noae collected from five locations along the southeastern Mediterranean coasts, Alexandria, Egypt. The frequency of the occurrence of ingested MPs in A. noae soft tissues was 48%, whereas the abundance of MPs was 1.65 ± 0.28 MP/individual and 0.58 ± 0.04 items g1 of the wet weight of tissue. Polyethylene was the most abundant polymer in A. noae, followed by polypropylene and polystyrene. The concentration levels of Zn, Cd, and Pb detected in the soft tissues of A. noae are higher than the maximum permissible limits. This study provides baseline data for further environmental assessments, with the use of A. noae as an early warning indicator in biomonitoring programs.

Source identification, seasonal and spatial variations of airborne dust trace elements pollution in Tehran, the capital of Iran

One of the main challenges in highly populated cities such as Tehran is air pollution, which originates mainly from rapid and irregular urbanization and industrialization. This study was carried out to investigate trace elements contamination in airborne dust of Tehran, the capital of Iran. Dust samples were collected from 44 different sites on a monthly basis from March 2016 to March 2017. Results of trace elements pollution using three factors of enrichment factor, contamination factor and pollution load index, revealed that the pollution has spread in all seasons and its highest amount was observed in the cold seasons, the results of these indices also showed Pb, Zn, Cd and As play an important role in air pollution in Tehran. Three main groups were identified in the sources analysis study: (1) Co and Fe, (2) As, (3) Ni, Cr, Cd, Pb and Zn. The first group does not seem to be much influenced by human activities and originates mostly from geogenic sources; but the second and third groups are mostly from anthropogenic sources. Traffic, fossil fuel combustion and industrial activities are among the most important human factors that have a significant impact on the amount of Trace elements in the dust.

Assessment oftrace elements pollution andtheir potential health risks in the cobalt-nickel bearing areas of Lomié, East Cameroon.

A study of trace elements pollution in the cobalt-nickel mining area of Nkamouna-Kongo (East Region of Cameroon) and their intimation to the risk of human exposure was carried out. A large spatial variability of concentrations was observed in the geochemical analysis of the trace elements in the thirty samples investigated. Trace element pollution in the investigated samples was assessed using the Regional Screening Level calculator of Environmental Protection Agency (USEPA) and the collected sample were analyzed using a SPECTRO XEPOS Energy Dispersive X-Ray Fluorescence analyzer (ED-XRF). The trace element concentrations in the analyzed samples followed the following order: Fe > Cr > Mn > Zr > Ni > Ba > Rb > Cu > Zn > Sr > Ga > Pb > Co > Rb > As > Sn. The averages of trace elements contamination factors followed a decreasing order:: Cr > Ni > Fe > As > Co > Cu > Zr > Ga > Pb > Mn > Zn > Y > Rb > Ba > Sn > Sr. Enrichment factor studies revealed that chromium (Cr) was severely enriched (indicating that Cr is the main element of the anthropic load) while elements such as Ni, Ba, Mn, Co, Cu, Zn, Ga, As, and Pb were moderately enriched. The associated health risk of human exposure was investigated using the Regional Screening Level of Environmental Protection Agency. It was found out that the carcinogenic risk to the exposed population from ingestion is high (2.5E-03), while the dermal risk is moderate (7.08E-04) and the inhalation risk is low (2.50E-07). The total non-carcinogenic risk from trace elements exposure for adults (HI = 1.5) and children (HI = 1.47E + 01) indicates that non-carcinogenic effects may occur in the vicinity of the study area.

Impacts of environmental pollution on mangrove phenology: Combining remotely sensed data and generalized additive models

Mangrove ecosystems worldwide have been affected by anthropogenic activities that modify natural conditions and supply trace elements that affect mangrove health and development. In order to gain a better understanding of these ecosystems, and assess the influence of physicochemical (granulometry, pH, salinity and ORP) and geochemical variables (concentrations of V, Cr, Co, Ni, Cu, Zn, Pb, Rb, Sr and Zr) on mangrove phenology, we combined field and satellite derived remotely sensed data. Phenology metrics in combination with Generalized Additive Models showed that start of the season was strongly influenced by Pb and Cu pollution as well as salinity and pH, with a large percentage of deviance explained (92.10%) by the model. Start of season exhibited non-linear delays as a response to pollution. Other phenology parameters such as the length of season, timing of the peak of season, and growth peak also indicated responses to both trace elements and physicochemical and geochemical variables, with percentages of deviance explained by the models ranging between 33.90% and 97.70%. While the peak of season showed delays as a response to increased pH and decreased salinity, growth peak exhibited a non-linear decrease as a response to increased Sr concentrations. These results suggest that trace element pollution is likely to lead to altered phenological patterns in mangroves.

Assessment of trace element pollution in northern and western Iranian agricultural soils: a review.

The pollution of Iranian agricultural soils with trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) was assessed and compared with other agricultural soils around the world. Experimental data on trace element content in Iranian agricultural areas in the west and north were collected from the literature: 39 studies covered a total of 46 agricultural sites of 17 provinces in Iran, in order to characterize their patterns of accumulation of trace elements. Two pollution indices, namely, the pollution index (PI) and the integrated pollution index (IPI), were used to evaluate trace element accumulation. The data revealed a remarkable variation in trace element content among soils in different areas. Exploratory data analyses (EDAs) showed that a number of trace elements (Pb, Cu, and Zn) are asymmetrically distributed and scattered. Surveys indicated that 45.5% of the studied samples had elevated PI values for Cd, 13.0% for Cu, and 16.7% for Pb, clearly indicating an anthropogenic contribution of these three elements. The IPI of the agricultural soils also indicated that most areas are classified as having moderate and high pollution. Higher contents of trace elements (except for Mn) were found in some cities of the Isfahan, Hamadan, and Tehran provinces. Excessive application of conventional and organic fertilizers, pesticides, animal manure, and sewage sludge for enhancing crop production is responsible for high trace element content in Iran's agricultural soils. This in turn, through the food chain, is a threat to human health. Analysis of the correlation between trace elements exhibited that Cu, Pb, and Zn(Cd, Pb and Zn) were very closely associated with each other, showing that their prevalent sources are common and the efforts to regulate them linked in common actions. We consider this evaluation as a viable approach to other similar areas in the Middle East and beyond, which could be used by environmental scientists for risk assessment and decision making.

Human Health Risks Associated with Trace Element Contamination of Crassostrea gasar (Dautzenberg, 1891) from Lake Zowla-Aného Lagoon Hydrosystem (Southern Togo)

Trace element pollution in aquatic ecosystems is one of the most important threats of human health and food chain. In order to assess the concentration of trace element in soft tissues of Crasostrea gasar and the human health risk associated with its consumption, seven trace elements (As, Hg, Pb, Cd, Zn, Cu and Cr) were analyzed by Atomic Absorption Spectrometer coupled to a hydride and cold vapour generator. C. gasar were collected at Zowla and Zalive in the Lake Zowla-Aneho Lagoon hydrosystem. The results showed a significant inter-site variation of trace elements concentrations. The highest concentrations (mg kg−1 dry weight) were obtained at Zalive (0.69, 40.61, 246.47, 13.34, 10.13, 908.57 and 0.31) and lower concentration at Zowla (0.48, 34.26, 165.1, 10.4, 6.43, 766.3 and 0.2) respectively for As, Cd, Cu, Cr, Pb, Zn and Hg. The estimated daily intake (EDI) of each trace element in children is greater than the EDI for adults. The target hazard quotient (THQ) for children is higher than that for adults. For children, only Hg had a THQ 1). Also, the cancer risk (CR) for As and Cr were higher than 10-4 indicating that the onset of carcinogenic effects related to As and Cr in children and adults is probable. This study, therefore, suggests that the current environmental levels of trace metals are potential threats to the health of regular consumers of C. gasar of this hydrosystem.

Risk assessment and source apportionment of trace elements in multiple compartments in the lower reach of the Jinsha River, China

Studies on trace element (TE) pollution in abiotic matrices have typically focused on water, sediment, and soil, either separately or in pairs. The importance of multi-media connectivity has been ignored. This study analyzed the concentrations of 6 TEs in three connected environmental compartments of a 28-km section of the lower reach of the Jinsha River. The ecological risk posed by TEs was higher in soil than in sediment. The contribution of exposure pathways to human health risk were ranked as ingestion > dermal contact > inhalation. An improved regional environmental risk index (RERI) method was then developed to evaluate the comprehensive risk on both ecology and human health caused by TEs. The average RERI value was generally higher in the wet season (0.42) than in the dry (0.41) and dry-to-wet transition seasons (0.08) because of the combined effects of the high TE concentrations in riparian soil and the long exposure time. Source apportionment indicated that industrial activities, weathering of parent rock, and agricultural activities were possible sources of TEs in this region. The methods and results of this study could inform local environmental management and provide references for similar cases wherein multiple compartments of river systems should be considered.

Ecological and human health risk assessment of trace element pollution in sediments and five important commercial fishes of the Oman Sea

The distribution of trace elements in sediments and five commercially important fish species of the Oman Sea were assessed using an atomic absorption spectrometer to determine ecological and human health risk assessment. The ranges of trace elements concentration in sediments were: Cr: 5.42-68.94, Zn: 5.22-18.11, Cu: 1.44-4.87, As: 18.07-79.96, Cd: 0.10-1.27, Ni: 43.0-65.34 and Pb: 8.92-30.53 mg/kg dry weight. Cr, Zn, Cu, Cd and Pb were below the ERL (effects range low) and TEL (threshold effect level) values at all the sampling stations with rarely biological effects. Whereas, As and Ni were higher than ERL and TEL with occasionally biological effects. The patterns of trace elements bioaccumulation in the tissues of all species were: liver> skin> gill> muscle. A significant positive correlation suggests that trace elements accumulation in fish is determined by trace elements in sediments. Estimated Daily Intake (EDI) was significantly lower than the tolerable daily intake (TDI) value. Target Hazard quotient (THQ), total target hazard quotient (TTHQ) and target carcinogenic risk (TR) values indicated no hazard risk from fish consumption. Hence, the consumption of concerned species to people in the Oman Sea is safe.

ASSESSMENT OF METAL POLLUTION IN INTER TIDAL AND BEACH SEDIMENTS ALONG NORTH EAST COAST OF TAMILNADU, INDIA

The concentrations of major (Al, Fe, Mg, Mn, Na, K and Ca) and trace (Cr, Cu, Ni, Pb and Zn) elements have been determined in inter tidal and beach surface sediments samples collected from North east coast of Tamilnadu, India. Major element analysis showed that the sediments had low concentrations when compared with crustal average and upper continental crust. Using sediment quality guidelines and different types of indexes, current trace elements pollution status in the study area were assessed. Sediment quality guidelines suggest that nickel and lead must be considered as a chemically potential concern in the study area. The indexes used in this study were enrichment factor, geo-accumulation index and modified degree of contamination. Different indexes gave diverse status of inter tidal and beach sediment quality. The results are discussed in the context of the sources and pathways of trace elements in the North east coast of Tamilnadu, India.

Advances in nutrient metabolism and emission of livestock and poultry dietary trace elements

<p indent=0mm>Trace elements, including iron, copper, manganese, zinc, selenium, and iodine, comprise less than 0.01% of animals, yet are essential nutrients and key factors in the plant-animal-soil cycle. Trace elements have important physiological functions and are often required for enzymatic reactions, energy metabolism, and synthesis of materials, immune defense, and other activities necessary for life. Micronutrient deficiency causes developmental disorders and decreased immunity in young animals, and even leads to nutritional metabolic diseases and death. Supplementation of the diet of livestock and poultry with trace elements is closely related to growth and reproductive performance. Many studies have demonstrated that dietary supplementation with trace elements improves production performance and the content of these elements in livestock and poultry products. Due to the low bioavailability of dietary trace elements, excess trace elements may be added to livestock and poultry diets. However, animals generally have self-regulatory mechanisms of absorption and metabolism to maintain the homeostasis of trace elements. Excess dietary trace elements that are not absorbed are discharged in the excrement and pollute farm soil and water sources. In particular, heavy metals, such as copper, zinc, manganese, chromium, and cadmium, detrimentally affect the growth of crops and change the composition and structure of soil microorganism. Human health can also be affected when heavy metals bioaccumulate through the food chain. Breeding and consumption of livestock and poultry occur on a large scale in China, the excrement from livestock and poultry is an important source of heavy metals in the environment. Soil, water, and crops in most areas of China are seriously affected by heavy metal pollution. Clarifying the nutrient metabolism and emission of dietary trace elements to reduce environmental con-tamination is crucial to improve the economic benefits of breeding, protect the ecological environment of breeding areas, and promote the healthy and sustainable development of the breeding industry. In recent years, increasing attention has focused on reducing environmental pollution caused by heavy metals from livestock and poultry, while maintaining the efficiency of breeding production. Appropriate reductions of trace elements in livestock and poultry diets do not impact growth performance and reduce the content of trace elements in excreta. In addition, organic trace element additives demonstrate higher bioavailability with less emission. This article summarizes the nutritional function, absorption and metabolism mechanism, enrichment characteristics of livestock and poultry products, and fecal excretion patterns of trace elements. The appropriate lower levels, improved dosage form of supplemented dietary trace elements, and a model of combined planting and breeding may alleviate trace element pollution in livestock and poultry breeding.

Potential environmental risk of trace elements in fly ash and gypsum from ultra–low emission coal–fired power plants in China

The ultra–low emission retrofitting (ULE) in China's coal–fired power plants (CFPPs) enhances removal efficiencies of trace elements, which may increase their contents in fly ash and gypsum. However, their potential environmental risks in these wastes have been scarcely evaluated. Experiments indicated that the trace elements in fly ash and gypsum accounted for approximately 92.9–98.2% of the total outputs. Most trace elements in these wastes existed mainly as mobile/leachable forms, except for the Hg in fly ash (residual form). We comprehensively evaluated the potential environmental risks of trace elements in fly ash and gypsum from ULE CFPPs in China using a modified risk assessment approach that integrates a trace element enrichment model for waste, and chemical speciation datasets. We found that nationally, trace elements in gypsum represented low levels of potential risk, even after ULE. However, the potential moderate environmental risk of fly ash has aroused attention because of trace element pollution, where Hg and Cd contributed the major risks. The relatively high risks from fly ash are mainly distributed in Guangxi, Hunan and Hebei provinces. The disposal of fly ash in these areas should be given special attention in the future.

Groundwater pollution and human health risk based on Monte Carlo simulation in a typical mining area in Northern Anhui Province, China

The main objective of this study was to evaluate eight kinds of trace element pollutants in groundwater from a typical coal mine area, and carry out a corresponding health risk assessment for the local populace. To do this, 34 shallow groundwater (SG) samples and 18 mid-layer groundwater (MG) samples were collected from the Sulin mining area. To minimize the uncertainties in the health risk assessment, this paper relied on Monte Carlo simulations and sensitivity analysis. The results revealed that Sr and Mn contents exceeded their corresponding WHO (Guidelines for drinking water quality, 4th edn. Geneva, 2011) guidelines and Chinese groundwater standards (GB/T14848–2017), while the other analyzed trace elements remain below those threshold values. The calculated hazard quotient and hazard index values for adults from ingestion exposure to SG and MG were well below the threshold limit of 1. Probabilistic simulations further show that the total cancer risk value above the limit of 1 × 10−6 is 0% for SG and 29.39% for MG. Sensitivity analysis identified the Sr and Cr contents as the most relevant element variables affecting the probabilistic non-carcinogenic and carcinogenic risk values in the model, respectively.

Comprehensive Assessment and Potential Ecological Risk of Trace Element Pollution (As, Ni, Co and Cr) in Aquatic Environmental Samples from an Industrialized Area.

A global assessment of arsenic (As), nickel (Ni), cobalt (Co) and chromium (Cr) was performed in environmental samples from an important industrial bay. Different fractions of water, sediments and tissues from four species of fish were analysed. Samples were collected from selected sampling sites during four consecutive samplings in spring and autumn seasons, in order to evaluate concentrations and their possible correlations among the aquatic compartments. While a higher availability of Cr and Ni was found in water, Co and As were the most available elements in sediments. In fish, the liver was the tissue with the highest proportion of As and Co, and gills showed the highest concentrations of Ni and Cr. Significance differences were observed among sites showing the pollution sources. In sediments, high correlations were found between total Co content and the most available fractions. Total Ni content highly correlated with the oxidisable fraction, while Cr total content tightly correlated with the least available fractions. Quality guideline values for sediments were frequently exceeded. In sediments and biota, concentrations were slightly higher than in other ecosystems, indicating that maritime, industrial and urban activities are affecting this type of ecosystem with great anthropogenic influence.

Predictive modeling of selected trace elements in groundwater using hybrid algorithms of iterative classifier optimizer

Trace element (TE) pollution in groundwater resources is one of the major concerns in both developing and developed countries as it can directly affect human health. Arsenic (As), Barium (Ba), and Rubidium (Rb) can be considered as TEs naturally present in groundwater due to water-rock interactions in Campania Plain (CP) aquifers, in South Italy. Their concentration could be predicted via some readily available input variables using an algorithm like the iterative classifier optimizer (ICO) for regression, and novel hybrid algorithms with additive regression (AR-ICO), attribute selected classifier (ASC-ICO) and bagging (BA-ICO). In this regard, 244 groundwater samples were collected from water wells within the CP and analyzed with respect to the electrical conductivity, pH, major ions and selected TEs. To develop the models, the available dataset was divided randomly into two subsets for model training (70% of the dataset) and evaluation (30% of the dataset), respectively. Based on the correlation coefficient (r), different input variables combinations were constructed to find the most effective one. Each model's performance was evaluated using common statistical and visual metrics. Results indicated that the prediction of As and Ba concentrations strongly depends on HCO3−, while Na+ is the most effective variable on Rb prediction. Also, the findings showed that the most powerful predictive models were those that used all the available input variables. According to models' performance evaluation metrics, the hybrid ASC-ICO outperformed other hybrid (BA- and AR-ICO) and standalone (ICO) algorithms to predict As and Ba concentrations, while both hybrid ASC- and BA-ICO models had higher accuracy and lower error than other algorithms for Rb prediction.

Assessment of trace element accumulation on the Tunisian coasts using biochemical biomarkers in Perinereis cultrifera

Our study aimed to evaluate the effect of trace element pollution in the polychaete Perinereis cultrifera (Grube, 1840) from two Tunisian coasts (the port of Rades, S1; and the Punic port of Carthage, S2). To this end, we used an approach based on proximate composition, biomarker responses and trace element bioaccumulation. Our results showed a decreasing order of metals concentrations (Zn&gt;Cu&gt;Cd&gt;Pb) in P. cultrifera from S1 and S2. The accumulation of Cd, Cu and Zn was significantly higher in S1 than in S2, especially in summer. Lipid, protein and glycogen content also changed significantly between S1 and S2 in relation to trace metal accumulation and environmental conditions. The results revealed a higher level of thiobarbituric acid in P. cultrifera from S1 than from S2. In addition, the enzymatic and non-enzymatic antioxidant defence system (catalase, glutathione-S-transferase, superoxide dismutase, glutathione and metallothionein) was enhanced and acetylcholinesterase activities decreased in P. cultrifera in S1 in comparison with S2. A principal component analysis showed that P. cultrifera from S1 exhibited a clear disruption of oxidative stress responses and trace element bioaccumulation among seasons. Overall, these findings revealed the sensitivity of those organisms to environmental conditions.

Trace elements concentration in soil and plant within the vicinity of abandoned tanning sites in Bangladesh: an integrated chemometric approach for health risk assessment

An effective toxicological assessment of soil-metal bioavailability and plant translocation processes is needed in view of the growing negative impact of trace element pollution on the terrestrial environment and human health. This study was conducted to assess the toxicological processes that regulate the plants’ trace element absorption into their tissues, the suitability for human use, the potential sources of trace elements, and the risk to human health, using an integrated research methodology. Soils and sweet potato plants were collected from agricultural fields near the tannery waste disposal sites of Dhaka City, Bangladesh and inductively coupled plasma mass spectrometers (ICP-MS) were used to analyze the essential and toxic elements. The mean concentrations of total elements in soil followed the descending order of Fe > Zn > Mn > Cr > Ni > Pb > Cu > As > Cd and in plant Fe > Zn > Cu > Cr > Ni > Mn > Pb > As > Cd. In the edible tissues of sweet potato, the concentrations of essential and toxic elements exceeded the maximum permissible levels, indicating not safe for human consumption. The translocation factor (TF) revealed that studied elements are more accumulated in the leaves than tubers. The enrichment factor revealed minimal to very high enrichment of essential and toxic elements in the plant parts while the contamination factor showed low to very high contamination. Considering the health risk of toxic elements from plant samples, As and Pb caused non-cancer and cancer risk on human health. However, the present results suggested that regular monitoring of these essential and toxic elements in soil and plants as well as other food materials around the abandoned tannery waste disposal sites are necessary to prevent excessive build-up of these elements in the food chain.

Potentially toxic trace element pollution in long-term fertilized agricultural soils in China: A meta-analysis

Fertilization results in potentially toxic trace element (PTTE) pollution in agricultural soils. However, it is unclear which factors determine the effect sizes of fertilization on PTTEs at the multiple spatial-temporal scale. This work synthesized 379 observations in 78 field sites (3–35 years) across China's main grain producing areas, and showed that long-term organic fertilization significantly enhanced total Cu, Zn and Cd by 25.7%, 18.9% and 66.6%, and soil available Cu, Zn and Cd by 60.5%, 155.3% and 83.6%, respectively; whereas long-term inorganic fertilization increased only available Cu, Zn and Cd by an average of 6.3%. Organic fertilizer (OF) type and application rate dominated the variation of PTTE concentrations, where approximately one-half of Cd pollution (42.6% of total Cd and 47% of available Cd) was observed. Furthermore, OFs containing Cd less than 1 mg kg−1 were recommended to be safely applied to agricultural soils. Soil type was main factor under long-term inorganic fertilization determining available PTTE variation, resulted in higher pollution risk in some soils such as Alfisols and Semi-hydromorphic soils, where we suggested the use of lower amounts of P fertilizers or the application of ones having small amounts of PTTEs. In short, long-term organic fertilization caused serious pollution of PTTEs especially Cd in Chinese croplands, and some strategies with a focus towards reducing the pollution risk must be developed, e.g., promoting straw return, forbidding Cd addition to feeds and feed additives, and improving carbon sequestration efficiency (CSE) of OFs and thus soil organic matter (SOM).