Predicting the risk of arsenic accumulation in soil-rice system in Asian monsoon region.

Rice is a staple food for a significant portion of the global population. Arsenic (As) accumulated in rice grains influences rice quality which threatens human health. In this study, we used three machine learning models to predict arsenic accumulation in rice based on over 300 surveys. The prediction results of soil arsenic indicate that high-arsenic soil areas are mainly distributed in South and Southeast Asia such as India, China, and Thailand. In addition, higher bioaccumulation factors (BAF), associated with higher temperature, are predominantly observed in eastern India and southern Myanmar. However, arsenic content in soil is relatively lower in these areas. About 5.5 billion population may be threatened by the consumption of high-arsenic rice. It can be concluded that temperatures may influence the BAF except for soil arsenic, and soil physicochemical properties. Further research on the relationship between climate parameters and BAF should be conducted to address and adapt to future climate change. Additionally, understanding the mechanism of arsenic accumulation under different climatic conditions is crucial for developing agricultural technologies to reduce arsenic accumulation in rice.

Optimizing cropland use to reduce groundwater arsenic hazards in a naturally arsenic-enriched grain-producing region.

In the Hetao Basin, a grain-producing region plagued by naturally occurring arsenic (As) pollution, understanding the role of agricultural cultivation activities in mobilizing As in groundwater is worthwhile. Here we investigated the impact of cropland use characteristics on groundwater As hazards using a model that combines Random Forest (RF) classification with SHapley Additive exPlanation (SHAP). The analysis incorporated eight cropland use characteristics and three natural factors across 1258 groundwater samples as independent variables. Additionally, an optimized cropland use strategy to mitigate groundwater As hazards was proposed. The results revealed that crop cultivation area, especially within a 2500m-radius buffer around sampling points, most significantly influenced the probability of groundwater As concentrations exceeding an irrigation safety threshold of 50 µg/L, achieving an AUC of 0.86 for this prediction. The relative importance of crop areas on As hazards were as follows: sunflower > melon > wheat > maize. Specifically, a high proportion of sunflower area (>30%), particularly in regions with longer cropland irrigation history, tended to elevate groundwater As hazards. Conversely, its negative driving force on groundwater As hazards was more pronounced with the increase in the proportion of wheat area (>5%), in contrast to other crops. Transitioning from sunflower to wheat or melon cultivation in the northeast of the Hetao Basin may contribute to lower groundwater As hazards. This study provides a scientific foundation for balancing food production with environmental safety and public health considerations.

Monthly variations of groundwater arsenic risk under future climate scenarios in 2081-2100.

The seasonal variations of shallow groundwater arsenic have been widely documented. To gain insight into the monthly variations and mechanisms behind high groundwater arsenic and arsenic exposure risk in different climate scenarios, the monthly probability of high groundwater arsenic in Hetao Basin was simulated through random forest model. The model was based on arsenic concentrations obtained from 566 groundwater sample sites, and the variables considered included soil properties, climate, topography, and landform parameters. The results revealed that spatial patterns of high groundwater arsenic showed some fluctuations among months under different future climate scenarios. The probability of high total arsenic and trivalent arsenic was found to be elevated at the start of the rainy season, only to rapidly decrease with increasing precipitation and temperature. The probability then increased again after the rainy season. The areas with an increased probability of high total arsenic and trivalent arsenic and arsenic exposure risk under SSP126 were typically found in the high-arsenic areas of 2019, while those with decreased probabilities were observed in low-arsenic areas. Under SSP585, which involves a significant increase in precipitation and temperature, the probability of high total arsenic and trivalent arsenic and arsenic exposure risk was widely reduced. However, the probability of high total arsenic and trivalent arsenic and arsenic exposure risk was mainly observed in low-arsenic areas from SSP126 to SSP585. In conclusion, the consumption of groundwater for human and livestock drinking remains a threat to human health due to high arsenic exposure under future climate scenarios.

The geochemical stability of typical arsenic-bearing sinter in the Tibetan plateau: Implications from quantitative mineralogy.

High­arsenic (As) sinter deposited from geothermal water is a potentially overlooked hazardous matrix and there remain substantial gaps in our comprehension of the stability of As sequestered within it. In this study, qualitative and quantitative analysis of the mineralogy of As-bearing sinter was conducted by Mineral Liberation Analyzer (MLA) in geothermal areas of the Tibetan Plateau to reveal the geochemical stability of As. Our results indicated that the contents of As in sinter were 3 orders of magnitude higher than the local soil. The dominant host minerals of As were calcite (40.9 %), thenardite (22.5 %), calcium silicate (13.0 %), and halite (8.1 %). Additionally, it was found that a relatively higher As bioavailability was extracted by ethylene diamine tetraacetic acid (EDTA), with a leaching rate of 41.2 %. Notably, the X-ray diffraction (XRD) showed that the thenardite and halite were decomposed after the leaching. The combination of mineralogy and geochemistry data suggested that calcite and calcium silicate were a crucial mechanism for As retention in sinter, while the dissolution of saline minerals (e.g., thenardite, halite, and calcium chloride) served as the primary sources for As release. This finding unveils the potential risks and mechanisms associated with high-As sinter, providing scientific guidance for risk management of sinter.

Selenium and Zinc Intakes of Staple Grains and Their Correlation with Urine Selenium and Zinc in the Tibetan Rural Residents along the Yarlung Zangbo River.

Grains account for a large proportion of the diet of rural residents in Tibet. The lack of selenium (Se) and zinc (Zn) threatens the population's nutrition and health. However, the intakes of selenium and zinc in grains remains unclear. To clarify the nutritional status of selenium and zinc consumed from staple grains of residents along the Yarlung Zangbo River in Tibet, 341 grain samples and 242 urine samples were collected, and 244 food frequency questionnaires were completed along the Yarlung Zangbo River in 2020-2021. The results showed that the selenium concentrations of 88.5% of self-produced tsampa and 80.8% of self-produced flour were lower than the grain selenium threshold (<25 µg·kg-1). The intake of selenium and zinc from staple grains (tsampa, flour, and rice) contributed 15.0% and 43.5% to the recommended nutrient intake (RNI) on average, respectively. A geographical detector model analyzed factors affecting urinary selenium and zinc levels. Selenium and zinc intakes in rice and flour, and dietary diversity score (DDS) were the main factors affecting urinary selenium and zinc (p < 0.01). Their interaction effects on urinary selenium and zinc were greater than those of a single factor. The staple grains of rural residents along the Yarlung Zangbo River were in a state of selenium deficiency. The zinc content of the staple grain purchased was lower than that of the main grain produced by rural residents. Changing the grain consumption pattern and adjusting the proportion of exogenous grains can improve selenium and zinc nutrition in residents.

Leaching characteristics and potential risk of heavy metals from drip irrigation pipes and mulch substrate in agricultural ecosystems.

Drip irrigation is a valuable method for optimising water and fertiliser usage, motivating its increasing use. However, the ecological effects of drip irrigation fertilisation have not been sufficiently evaluated, limiting its effective and widespread use. Within this context, we aimed to determine the effects and potential ecological risks of using polyethylene irrigation pipes and mulch substrate under various drip irrigation conditions as well as burning of waste pipes and mulch substrate. Laboratory simulations of field conditions were used to determine the distribution, leaching, and migration pattern of heavy metals (Cd, Cr, Cu, Pb, and Zn) from plastic drip irrigation pipes and agricultural mulch substrate into various solutions. Maize samples obtained from drip-irrigated fields were analysed to determine the presence of heavy metal residues and assess the risk of heavy metal contamination. Heavy metal leaching from pipes and mulch substrate was high under acidic conditions, while the migration of heavy metals from plastic products was low in alkaline water-soluble fertiliser solutions. After combustion, heavy metal leaching from pipes and mulch residues increased considerably, with the migration capacity of Cd, Cr, and Cu increasing by >10-fold. Heavy metals in plastic pipes migrated primarily to the residue (bottom ash), whereas those from mulch substrate migrated to the fly ash component. Under experimental conditions, the migration of heavy metals from plastic pipes and mulch substrate had a negligible effect on the heavy metal content in aqueous environments. Although heavy metal leaching increased, the effect on water quality under actual irrigation conditions was relatively minor (in the order of 10-9). Thus, the use of plastic irrigation pipes and mulch substrate did not result in significant heavy metal contamination and potential risk to the agriculture ecosystem. Our study findings provide evidence for the effective application and widespread promotion of drip irrigation and fertiliser technology.

Characteristics, sources, and risk assessment of thallium and associated with metal(loid)s in the Yarlung Tsangpo River Basin, southern Tibetan Plateau.

The Tibetan Plateau (TP) is known as the water tower of Asia, and the water quality has long been a focus of public concern, especially in the Yarlung Tsangpo River Basin (YTRB), a unique area that is climate-sensitive, geologically complex, eco-fragile, and densely populated. Thallium (Tl) is a typical metal that is more toxic than Pb, Cd, and As and often occurs in sulfide minerals. Although large-scale polymetallic sulfide mineralization developed in the YTRB, the geochemical dispersion and potential risk of Tl in aquatic environments of the YTRB remain poorly understood. In this study, the concentration, distribution, source, and health risk of Tl and associated metal(loid)s in the hot springs and surface water in the YTRB were systematically analyzed. The results showed that the trace elements (Cd, Cr, Zn, Cu, Al, Sr, Ni, Co, Mn, Pb) in water environments are within the recommended limits, except for Tl and As. Principal component analysis (PCA) and correlation analysis (CA) showed that the elements of Tl and As were positively related to each other in either both hot spring water and surface water, indicating their common origin. Spatial variations suggested that high levels of Tl and As observed in the north YTRB, which may be relevant to the reduction-dissolution of Tl (As)-bearing minerals and the magmatic hydrothermal system formed in the shallow part of the northern YTRB. Furthermore, source apportionment identified natural sources of Cu, Ni, Cr, Co, Mn, Zn, and Cd and anthropogenic inputs of Al and Pb. Exposure assessment studies have found that ingestion is the primary route of As and Tl exposure to local population, and balneological and bathing purposes do not constitute a human health concern. This study offers valuable insights into the risk of naturally occurring Tl enrichment being hidden in As-rich hydrosphere in the YTRB and other regions with similar geoenvironmental contexts.

Incorporating Exercise Efficiency to Evaluate the Accessibility and Capacity of Medical Resources in Tibet, China.

Accessibility and capacity of medical resources are key for the health care and emergency response, while the efficiency of the medical resources is very much limited by hypoxia in Tibet, China. Through introducing exercise efficiency, this study explores the accessibility of township residence to county-ship medical resources in Tibet using weighted mean travel time (WMT), and evaluates the medical capacity accordingly. The results show that: 1) the average travel time of township residence to county-level hospital is around 2 h by motor vehicle in Tibet. More than half of the population can not reach the county-ship hospital within 1 h, 33.24% of the population can not reach within 2 h, and 3.75% of the population can not reach within 6 h. 2) When considering the catchment of the medical resources and the population size, the WMT of the county-ship medical resources ranges from 0.25 h to 10.92 h. 3) After adjusted by travel time and exercise efficiency, the county-ship medical capacity became more unequal, with 38 out of 74 counties could not meet the national guideline of 1.8 medical beds per 1000. 4) In total, there are 17 counties with good WMT and sufficient medical resources, while 13 counties having very high WMT and low capacity of medical resources in Tibet. In the end, suggestions on medical resources relocation and to improve the capacity are provided. This study provides a method to incorporate exercise efficiency to access the accessibility and evaluate medical capacity that can be applied in high altitude ranges. Electronic Supplementary Material: Supplementary material is available in the online version of this article at 10.1007/s11769-022-1321-1.

Understanding the spatial diffusion dynamics of the COVID-19 pandemic in the city system in China.

Investigating the spatial epidemic dynamics of COVID-19 is crucial in understanding the routine of spatial diffusion and in surveillance, prediction, identification and prevention of another potential outbreak. However, previous studies attempting to evaluate these spatial diffusion dynamics are limited. Using city as the research unit and spatial association analysis as the primary strategy, this study explored the changing primary risk factors impacting the spatial spread of COVID-19 across Chinese cities under various diffusion assumptions and throughout the epidemic stage. Moreover, this study investigated the characteristics and geographical distributions of high-risk areas in different epidemic stages. The results empirically indicated rapid intercity diffusion at the early stage and primarily intracity diffusion thereafter. Before countermeasures took effect, proximity, GDP per capita, medical resources, outflows from Wuhan and intercity mobility significantly affected early diffusion. With speedily effective countermeasures, outflows from the epicenter, proximity, and intracity outflows played an important role. At the early stage, high-risk areas were mainly cities adjacent to the epicenter, with higher GDP per capita, or a combination of higher GDP per capita and better medical resources, with more outflow from the epicenter, or more intercity mobility. After countermeasures were effected, cities adjacent to the epicenter, or with more outflow from the epicenter or more intracity mobility became high-risk areas. This study provides an insightful understanding of the spatial diffusion of COVID-19 across cities. The findings are informative for effectively handling the potential recurrence of COVID-19 in various settings.

Dietary and Food Consumption Patterns and Their Associated Factors in the Tibetan Plateau Population: Results from 73 Counties with Agriculture and Animal Husbandry in Tibet, China.

Dietary imbalances are an important cause of morbidity and mortality, both in China and globally. Abnormal element content in the natural environment and the unbalanced dietary structure of populations coexist in the Tibetan Plateau. This study analyzed the dietary and food consumption patterns of 617 Tibetan residents and their associated factors. Cluster analysis revealed three modes of dietary pattern; the food consumption scores (FCSs) of subjects in modes with relatively high consumption frequency of staple food and relatively singular dietary structure were the lowest. Although the FCSs of most subjects were acceptable (FCS > 35), subjects with relatively low FCSs were more dependent on locally cultivated highland barley that is probably low in selenium. Hierarchical linear models revealed both individual−family and regional factors were significantly related (p values < 0.05) with the food consumption of subjects as follows: age, travel time from township to county, and cultivation area of highland barley were negatively related; numbers of individuals aged 40−60 years and pork, beef, and mutton production were positively related. Individuals with secondary or higher education had higher FCSs. A single indicator may be incomprehensive in dietary and food consumption studies. For people with a relatively unbalanced diet, an analysis of the main foods they consume is critical. Dietary and food consumption patterns might have relatively large inter-regional and intra-regional variations; therefore, factors that influence it might be multi-level and multi-scale.

Plastic shed production systems: The migration of heavy metals from soil to vegetables and human health risk assessment.

Plastic shed production system (PSPS) provide abundant vegetable products for human consumption. Comprehensive and accurate heavy metal (HM) risk assessment of soil and vegetable under plastic sheds is crucial for human health. Pollution assessment, bioavailability and mobility evaluation and health risk assessment of Cd, Cr, Cu, Zn Ni, Pb, and As were performed in a presentative Plastic shed production system. The concentrations of the Cd, Cu and Zn exceeded their background value. Positive Igeo values suggested that soil under plastic sheds was widely contaminated with Cd. The bioavailability of heavy metals in soils was evaluated using DTPA extraction and DGT methods. The results of both methods demonstrated that Cd, Cu, and Zn have high bioavailability, especially Cd. Analogically, the results of mobility assignment based on DIFS showed that Cd has a high migration risk due to the large available pool. Based on specific cultivation and management patterns of plastic shed production system, pH reduction and salt and nutrient accumulation may increase the heavy metals migration risk in soil under plastic sheds, while a high organic matter content may reduce the heavy metals migration risk. The average concentrations of Cd, Cr, Cu, Zn, Ni, Pb, and As in vegetables were 0.023, 0.226, 0.654, 2.984, 0.329, 0.041, and 0.010 mg/kg, respectively. All samples were well below the threshold. The order of target hazard quotient of different heavy metals caused by vegetable consumption was Cd > Cr > As > Cu, Ni, Pb, Zn, and the average total hazard index value was below 1, which demonstrated that risk of vegetable consumption in the study area. However, due to its high concentration and transfer coefficient in spinach, Cd might pose a health risk to humans, which requires special attention. In this study, Cd caused a significant issue than other HMs, whether pollution level, health risk and migration risk. DGT and DIFS can be used as an effective evaluation tool in the research of controlling heavy metals migration in soil-crop systems.

Bioaccumulation and translocation of trace elements in soil-irrigation water-wheat in arid agricultural areas of Xin Jiang, China.

Pollution resulting from toxic trace elements is an increasing concern around the world especially in developing countries such as China. Rapid industrialisation, urbanisation and agricultural development are the dominant sources of anthropogenic contamination contributed to an increased potential toxicity of trace elements in the irrigation water-soil-food chain. Xin Jiang in China is a reserved cultivated land development area that could provide the most extensive strategic support for food production and arable land security in China. Thus, it is crucial to investigate the bioaccumulation and translocation of trace elements in order to assess the ecological and human health risks in the traditional oasis system of the agricultural areas in Bay Cheng County, Xin Jiang. This study analysed the levels of trace elements in different layers of the soil, the irrigation water and the wheat plants, and the relationships among them. The results indicated that cadmium (Cd) and chromium (Cr) were the primary pollutants in soils and wheats respectively, and they fell into the serious pollution category. However, no trace elements over the pollution limits were detected in irrigation water. The maximum values of trace elements appeared in the soil layers at 5-10 cm and 10-15 cm. The pollution levels of trace elements in the soil layers were found at 0-5 cm and 0-20 cm, which were higher than those at 20-80 cm. In wheat, high amounts of absorption for Se, Cr, Zn and Cu, but low for Pb were detected in different parts of a plant. The roots of wheats were more eco-toxic to Cd, Co and Pb than other tissues, indicating that roots were more effective at absorbing Cd, Co and Pb, as these metals are usually toxic in the soil. Se, Cu and Zn showed a higher ability of being transferred from soils to the edible parts of crops. The bio-transfer factors of Zn, Mo, Cu, Mg and Mn were considerably higher than those of other elements. The average cancer risk of As, Cd, Co, Ni and TCR in wheat grains exceeded the safety reference limit (1 × 10-4). For the exposed population, Cr in wheat was the major contributor to total cancer risk. The average values of HQ of Cr, Mn and As, and total non-cancer risk index exceeded the corresponding effective safe reference doses (HQ > 1).

The Availability and Accumulation of Heavy Metals in Greenhouse Soils Associated with Intensive Fertilizer Application.

In China, greenhouse agriculture, which provides abundant vegetable products for human consumption, has been rapidly developed in recent decades. Heavy metal accumulation in greenhouse soil and products obtained have received increasing attention. Therefore, the availability and accumulation of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) and their association with soil pH, soil organic matter (SOM), inorganic nitrogen (IN), total nitrogen (TN), available phosphorus (AP), and planting year (PY) in greenhouse soils were analyzed. The results showed that the mean concentrations of available Cd, Cu, Ni, Pb, and Zn were 17.25 µg/kg, 2.89, 0.18, 0.36, and 5.33 mg/kg, respectively, while their suggested levels in China are 0.6, 100, 100, 120, and 250 mg/kg. Cd, Cu, and Zn might be mainly originated from fertilizer application. A lower soil pH significantly increased the available Cu, Ni, and Zn concentrations and reduced Cd, Cu, Ni, and Zn accumulation. A higher AP significantly increased the proportions of available Cu, Ni, and Zn and elevated Cd, Cu, and Zn accumulation. There was a strong positive correlation between Cd, Pb, and Zn availability and TN, while IN was negatively related to the availability and accumulation of Cu and Zn. It was concluded that chemical fertilizer application increased the availability of Cu, Ni, Pb, and Zn and the accumulation of Cd, Cu, and Zn. Manure application clearly elevated the accumulation and availability of Cd and Zn in greenhouse soil.

Changes in urinary arsenic species and methylation capacity in original arsenic exposure cohort after water quality improvement.

Water quality improvement is the most efficient way to prevent arsenic exposure. After the cessation of arsenic ingestion, arsenic methylation capacity of the exposed population can change significantly. The factors associated with these changes remain poorly understood. Therefore, arsenic methylation capacity in a study cohort was estimated before and after water quality improvement in the present study. Results indicated that urinary content of the arsenic species in the study cohort significantly decreased after water quality improvement. In addition, the proportions of inorganic arsenic (%iAs) and monomethyl arsenic acid (%MMA) were significantly decreased, while proportions of dimethyl arsenic (%DMA) increased. The primary methylation index (PMI) and secondary methylation index (SMI) increased from 0.85 to 0.92 and 0.82 to 0.84, respectively. Arsenic species urinary content and arsenic methylation index varied slightly between the study cohort after water quality improvement and the control cohort. The rate of increase in PMI was higher than that in SMI. The study group aged 31-50 years had the highest increase in PMI. Logistic regression revealed that %DMA before water quality improvement was negatively associated with the increase in PMI, while %iAs were positively related, and %MMA were positively associated with the increase in SMI. It is concluded that urinary arsenic species content and arsenic methylation capacity increased to the levels of the control cohort after water quality improvement. An increase in primary arsenic methylation capacity may be a burden on the secondary arsenic methylation capacity. The main role of arsenic methylation capacity recovery may be the cessation of arsenic exposure.

A follow-up study of the development of skin lesions associated with arsenic exposure duration.

Little information about the development of skin lesions in relation to arsenic exposure duration is available. Therefore, skin lesions in a cohort from the Bameng region of China were diagnosed in 2012 and 2017. The results indicated that the prevalence of hyperkeratosis, pigmentation and depigmentation in 2017 was 64.67, 6.67 and 12.67%. There were 42 and 34% of male subjects and female subjects suffered from skin lesions in 2012. Their morbidity rates were 10.43 and 8.98 per 1000 person-years. In 2017, the values were significantly increased. The prevalence and morbidity rate of skin lesions were positively correlated with age and arsenic levels in drinking water. Males had higher prevalence of skin lesions compared with female. However, the ≤ 40 years female group had higher prevalence of skin lesions. In addition, the increased rate of skin lesions prevalence was negatively correlated with arsenic levels in drinking water. The odds ratios (ORs) showed that the risks of skin lesions were positively associated with the proportion of inorganic arsenic (%iAs) and monomethylarsonic acid (%MMA) in urine, and negatively correlated with arsenic methylation capacity in both 2012 and 2017. It can be concluded that females immigrated from other areas were more susceptible to developing skin lesions. A certain cumulative arsenic exposure dose, which may be existing, significantly increased the prevalence of skin lesions. Longer arsenic exposure duration might elevate the toxicity of iAs to skin lesions and reduce the positive effects of arsenic methylation capacity on skin lesions.

Effects of arsenic methylation and metabolism on the changes of arsenic-related skin lesions.

Little was known about the arsenic metabolism and arsenic methylation associated with the changes of skin lesions after reducing the arsenic in drinking water (WAs). Therefore, urinary concentrations and proportions of arsenic species were determined for recovery (RC), improvement (IC), persistent (PE), aggravation (AC), new incidence (NC), and no sign (HC) groups based on the changes of skin lesions between before (in 2004) and after (in 2017) WAs reduction. The results indicate that the urinary concentrations of inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and total arsenic (TAs) were much higher for RC and IC groups than for the other groups in 2004, while these values varied slightly among the groups in 2017. The urinary %iAs of all the groups was significantly decreased after WAs reduction. In contrast, the urinary %DMA of RC, IC, AC, and NC groups was increased. From 2004 to 2017, the PE and HC groups had lower decrease rate of %iAs and %MMA, and increase rate of %DMA, primary methylation index (PMI), and secondary methylation index (SMI) after WAs reduction. The adjusted odd ratios (ORs) showed that the RC, IC, AC, and NC groups were positively related with %iAs and %MMA and were negatively correlated with %DMA, PMI, and SMI before WAs reduction. It can be concluded that higher urinary %iAs and %MMA before WAs reduction increased the probability of skin lesions recovery and improvement, and the risks of skin lesions aggravation and incidence. Higher increase rate of urinary %DMA was positively associated with of skin lesions recovery and improvement. Moreover, higher urinary %iAs and %MMA or lower increase rate of urinary %DMA might increase the risk of skin lesions aggravation.

Temporal Variation and Ecological Risk Assessment of Metals in Soil Nearby a Pb⁻Zn Mine in Southern China.

Metal contamination in soil from tailings induces risks for the ecosystem and for humans. In this study, the concentrations and ecological risks of Cd, Cu, Pb, and Zn in soil contaminated by a tailing from Yangshuo (YS) lead and zinc (Pb⁻Zn) mine, which collapsed for more than 40 years, were determined in 2015. The mean concentrations of Zn, Pb, Cu, and Cd were 1301.79, 768.41, 82.60, and 4.82 mg/kg, respectively, which, with years of remediation activities, decreased by 66.9%, 61.7%, 65.4%, and 65.3% since 1986, but still exceed the national standards. From 1986 to 2015, soil pH increased significantly, with available concentrations of Zn, Pb, Cu and Cd decreasing by 13%, 81%, 77%, and 67%, respectively, and potential ecological risk indexes (Er) of the determined metals decreasing by more than 60%. Horizontally, total contents and percentages of available concentrations of Zn, Pb, Cu, and Cd decreased with the distance from the tailing heap in SD village, while pH values showed the reverse pattern. Vertically, Zn and Cd, Pb, and Cu showed similar vertical distribution patterns in the soil profiles. There was a slight downward migration for the determined metals in soil of M and H area and the mobility was in the order of Cd > Zn > Pb > Cu. It can be concluded that although concentrations and ecological risks of Cd, Cu, Pb, and Zn in soil decreased significantly, SD village is still a high risk area, and the priority pollutant is Cd.

Dietary selenium intake based on the Chinese Food Pagoda: the influence of dietary patterns on selenium intake.

BACKGROUND: Selenium (Se) is essential for humans, with many critical roles in physiological and pathophysiological processes. Fish, eggs and meats are usually the rich food sources of Se. To improve the nutritional status of population, a new version of balanced dietary pattern in the form of the Chinese Food Pagoda (2016) was proclaimed. This study aimed to evaluate the contribution of this balanced dietary pattern to daily Se intake, and to assess Se intake status of Chinese residents under this Food Pagoda scenario. METHODS: Based on the food consumption recommended in the Food Pagoda, this study collected the data of Se contents in various food composites and estimated dietary Se intakes (EITDS) in 12 provinces from the 4th China Total Diet Study. The estimated Se intakes based on the Chinese Food Pagoda (EICHFP) in 12 provinces were calculated. EITDS and EICHFP in various food groups among different regions were compared. RESULTS: The average EICHFP in all regions, within the range of 66.23-145.20 µg/day, was greater than the China recommended nutrient intake (RNI) (60 µg/day). None of the highest EICHFP went beyond the tolerable upper intake level of Se (400 µg/day). Animal source foods should be the primary source of daily Se intake according to the EICHFP. The average EITDS in China (88 µg/day) was in line with its range of EICHFP (81.01-124.25 µg/day), but that in half of the regions failed to achieve their lowest EICHFP. Significant differences between EITDS and EICHFP were observed in cereal food, aquatic and dairy products (P < 0.05), among which Se intake from aquatic and dairy products presented seriously insufficient in almost all regions. CONCLUSIONS: The ideal dietary pattern recommended in the Food Pagoda can meet the daily requirements of Chinese population for Se intake to maintain optimal health. From the perspective of the balanced diet and Se-rich sources, the consumption of aquatic products should be increased appropriately to improve the general Se intake level of Chinese population.

Trace Metals in the Urine and Hair of a Population in an Endemic Arsenism Area.

There have been few investigations of trace elements in the urine and hair of populations exposed to high levels of arsenic (As) in drinking water. Therefore, concentrations of selected metals in urine and hair samples from a population in a study area where arsenism was endemic and a control area were determined. It was found that the median concentrations of barium (Ba), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), zinc (Zn), and As in the urine samples from the population in the study area were 3.87, 0.47, 0.50, 61.84, 26.82, 1.33, 128.45, 7.05, 1.10, 233.75, and 339.63 µg/L, respectively. The corresponding values in the urine samples from a population in the control area were 29.08, 0.19, 0.21, 27.77, 10.32, 4.61, 14.01, 2.19, 3.90, 113.92, and 20.28 µg/L, respectively. In the study area, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, and Zn excreted in the urine were likely to be mainly derived from drinking water with high levels of arsenic. The median concentrations of Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Zn, and As in the hair samples from the study area were 4.16, 0.03, 0.09, 1.09, 6.54, 1.97, 0.06, 0.53, 1.64, 144.28, and 1.67 mg/kg, respectively. The corresponding values from the control area were 4.76, 0.03, 0.02, 1.41, 8.31, 1.34, 0.07, 0.39, 0.86, 154.58, and 0.29 mg/kg, respectively. Significant positive correlations were observed between As and Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, and Zn in the urine in the study area. However, As was not positively associated with these metals in the hair samples. Exposure to high levels of As in drinking water increased the accumulation of Ba and Mn in the hair and the excretion of Cd, Cu, and Mo in the urine in the study area. The population in the study area might experience Cu and Mo deficiencies for an increasing excretion of Cu and Mo.