Assessment of heavy metal contents in surface soil in the Lhasa-Shigatse-Nam Co area of the Tibetan Plateau, China

Exposure of Tibetan pregnant women to antibiotics in China: A biomonitoring-based study

Tibetan people are one Chinese ethnic minority living in Qinghai-Tibet Plateau with an average altitude of more than 4500 m. High altitude could cause a different antibiotic exposure, but relevant information is limited in Tibetan people. We investigated 476 Tibetan pregnant women in Lhasa, Tibet in 2021 and measured 30 antibiotics from five categories in urine, including 13 veterinary antibiotics (VAs), five human antibiotics (HAs), and 12 human/veterinary antibiotics (H/VAs). Food consumption was investigated by a brief food frequency questionnaire. Health risk was assessed by hazard quotient (HQ) and hazard index (HI) based on acceptable daily intakes (ADIs). All antibiotics were overall detected in 34.7% of urine samples with the 75th percentile concentration of 0.19 ng/mL (0.35 μg/g creatinine). HAs, VAs, and H/VAs were respectively detected in 5.3%, 13.0%, and 25.0% of urine samples, with the 95th percentiles of 0.01 ng/mL (0.01 μg/g creatinine), 0.50 ng/mL (0.99 μg/g creatinine), and 3.58 ng/mL (5.02 μg/g creatinine), respectively. Maternal age, smoking of family members, and housework time were associated with detection frequencies of HAs, VAs, or sum of all antibiotics. Pregnant women with a more frequent consumption of fresh milk, egg, yoghourt, poultry meat, and fish had a higher detection frequency of VAs or H/VAs. Only ciprofloxacin and tetracycline had a HQ of larger than one based on microbiological effect in 1.26% and 0.21% of pregnant women, respectively and a HI of larger than one was found in 1.47% of pregnant women. The findings suggested that there was an evident antibiotic exposure from various sources in Tibetan pregnant women with some basic characteristics of pregnant women as potential predictors and several animal-derived food items were important sources of exposure to antibiotic with a fraction of pregnant women in the health risk related to microbiological disruption of gut microbiota.

Spatial distribution and ecological risk assessment of heavy metals in alpine grasslands of the Zoige Basin, China

Heavy metals elements are not only related to the functions of ecosystems but also affect human health. To understand the characteristics of heavy metals in the topsoil of the Zoige alpine basin, a total of 252 grass and topsoil samples were collected in May and September 2014. The results showed that only Cd and Pb highly exceeded their background values (BV); in May and September, Cd was 2.02- and 1.55-fold higher than its BV, respectively, and Pb was 2.35- and 2.17-fold above its BV, respectively. The sources of Cd and Pb were homologous. In addition, the comprehensive potential ecological risk index was less than 150, indicating that heavy metal pollution in the study area is currently low. The spatial interpolation indicated that Cd and Pb pollution might be related to tourism and transportation, but the low biological absorption coefficient for all heavy metals showed that heavy metal absorption ability of forage was low and would not impact yak breeding. Finally, the soil was lightly contaminated by Cd and Pb due to the rapid development of the animal husbandry and tourism. The spatial variation of heavy metal in the basin is dominated by structural factors, and the random factors also have an effect on spatial distribution of As, Cd, Cu and Ni. The random factors such as overgrazing can exert an influence on physical structure and the circulation of nutrient substances of meadow soil through livestock grazing and trampling, ultimately affecting the content and distribution of soil heavy metals.

Spatial Distribution, Pollution, and Ecological Risk Assessment of Metal(loid)s in Multiple Spheres of the Shennongjia Alpine Critical Zone, Central China

The development of Earth's critical zone concept has strengthened the capacity of environmental science to better solve real-world problems, such as metal(loid) pollution in the remote alpine areas. The selected metal(loid) contents in soil, moss, and water were investigated to explore the geochemical distribution patterns, pollution levels, and potential ecological risks of metal(loid)s in the Shennongjia (SNJ) alpine critical zone of central China. The distribution of metal(loid)s in different spheres had horizontal and vertical differences. The maximum V, Ni, and Zn contents in water occurred at the sampling sites close to the Hohhot-Beihai Highway, while Dajiuhu Lake had the maximum Cu, Cr, and Mn contents. Most metal(loid) contents in the mosses showed an increasing trend from the northeast low-altitude area to the southwest high-altitude area, while As, Co, V, Ni, Cr, and Zn in soil decreased significantly with altitude and were enriched near the service areas and the highway. The contents of water Co and Ni, soil Cu and Mn, and moss As were evenly distributed and showed no significant differences with altitude. The enrichment factors, pollution index, Nemerow integrated pollution index, geo-accumulation index, heavy metal pollution index, contamination factor, and potential ecological risk index (PERI) were used to assess the pollution levels and ecological risks of SNJ soil, water, and atmosphere. The overall pollution levels of SNJ soil, moss, and water were low to moderate, low, and low, respectively. Soil V, Cu, Zn, moss As, Co, V, and Dajiuhu Lake water Mn were the main pollution factors. The ecological risks in the three spheres of the SNJ alpine critical zone were low to moderate, and As, Co, and V were the most critical potential ecological risk factors. The metal(loid)s pollution problem caused by the continuous development of tourism needs further attention.

Water quality and health risk assessment of the water bodies in the Yamdrok-tso basin, southern Tibetan Plateau

Water resources in good quality guarantee the primary condition for the maintenance and development of the natural ecosystem and human society. Water quality status and health risk of the lake water bodies in the national nature reserve, the Yamdrok-tso basin, in the southern Tibetan Plateau are assessed by 25 water parameters including 12 heavy metal(loid)s. Results reveal that the lake water bodies possess relatively high pH (9.68), high concentrations of F (1.66 mg/L), Cu (13.92 μg/L), As (41.60 μg/L), Pb (26.69 μg/L), and U (19.53 μg/L), and a low value of dissolved oxygen (19.30%). The pollution indices (heavy metal pollution index of 0.88-22.88, heavy metal evaluation index of 0.18-3.75, and the degree of contamination of -8.82 to -5.25) demonstrate that the lake water bodies are in a low pollution level with respect to heavy metal(loid)s. The evaluation of water quality based on the fuzzy comprehensive assessment method suggests that 75.56% of the water samples meet the regulation of the China National Standard for water resources in national nature reserves. Health risk assessment shows that potential hazards exist on this region when the residents under long-term exposure to the lake water through oral and dermal pathways, of which children and adults are mostly exposed to As and F for non-carcinogenic and As for carcinogenic risks, especially for children. Results of this study contribute to targeted water resources management in the national nature reserves.

Pollution and Risk Assessment of Heavy Metals in the Sediments and Soils around Tiegelongnan Copper Deposit, Northern Tibet, China

The surface sediments of the Rongna River and the surface soils around the Tiegelongnan copper deposit were collected, and the heavy metals Cu, Zn, Pb, Cr, Cd, As, Hg, and Ni were measured for their concentrations and health risk assessment. When the Rongna River passed through the Cu deposit area, the concentrations of Cu, Zn, As, Cd, Ni, and Hg in the surface sediments increased significantly, and the concentrations of Cu, Zn, and As exceeded the corresponding Grade II environmental quality standard. The heavy metals in the soil of the mining area were greater than the background value of the soil in Tibet. The geoaccumulation index indicated that the sediments of the river entering the mining area were very highly polluted by Cu and moderately polluted by Cd and Zn, and the soils in the mining area were moderately polluted by Cu. The potential ecological risk (PER) indices revealed that the sediments of the river entering the mining area had significantly high ecological risks, while the PER of the sediments away from the river section of the mining area was low, and the PER of the soils around the Cu deposit was moderate. The results of the health risk assessment indicated that the noncarcinogenic risks of heavy metals in sediments and soil of the mining area were within the acceptable range for adults and children. However, the carcinogenic risk of As and Cd in the sediment and As in the soil exceeds the relevant national standards, which may pose a certain risk to human health.

Relationship between traditional maternal diet pattern and breastmilk composition of rural lactating women during the first month postpartum in Shigatse, Tibet

Maternal nutrition can influence the composition of human breastmilk by altering the components that are sensitive to maternal diet pattern. Traditional Tibetan maternal diet pattern among native rural lactating women possesses distinct characteristics due to its unique geographical environment and dietary habits. This study investigated maternal diet pattern and human breastmilk composition of Tibetan lactating women through different lactation stages during the first month postpartum in Shigatse. The results indicated that Tibetan maternal diet profile was apparently monotonous, mainly sufficient in Zanba, buttered tea, red meat, and fatty soup, yet insufficient in white meat, eggs, leafy vegetables, and fruits, leading to imperfect maternal nutritional intakes with high-level carbohydrates and deficient proteins. Distinctions of maternal diet profiles in various degrees can be discovered upon different lactation stages, which brings multiple influences to the composition of human milk. There was significantly weak-to-medium correlation of protein contents between maternal diet intakes and human milk, while other macronutrients correlated insignificantly. Micronutrient constituents in human milk, involving functional unsaturated fatty acids and free essential amino acids, were also impacted by maternal diet intakes through different lactation stages. These results show that more systematic and profound research is requisite for the clarification and development of Tibetan maternal diet to offer more enhanced and individualized nutritional recommendations for Tibetan lactating women and infants.

Assessment of Soil Contamination with Potentially Toxic Elements and Soil Ecotoxicity of Botanical Garden in Brno, Czech Republic: Are Urban Botanical Gardens More Polluted Than Urban Parks?

Though botanical gardens are an important and widely visited component of urban green spaces (UGS) worldwide, their pollution is rarely studied. The aim of this study was to assess botanical garden soil contamination and ecotoxicity and to evaluate whether urban botanical gardens are more contaminated than urban parks. Soil assessments showed serious contamination with Cd, Pb and Zn, emitted predominantly by traffic, agrochemicals and past construction and demolition waste. The discovery of hazardous historical ecological burden in the UGS calls for the necessity of detailed surveys of such areas. Despite prevailing moderate-to-heavy contamination, the soil was only slightly ecotoxic. Maximum immobilisation inhibition of Daphnia magna reached 15%. Growth of Sinapis alba L. was predominantly stimulated (73%), and Desmodesmus subspicatus Chodat was exclusively stimulated, possibly due to soil alkalinity and fertiliser-related nutrients. The hypothesis of a higher contamination of urban botanical gardens compared to urban parks was confirmed. However, urban parks can face a greater risk of soil ecotoxicity, hypothetically due to decreased activity of soil organisms resulting from adverse soil conditions caused by active recreation. The results highlight the need for an increased focus on botanical and ornamental gardens when assessing and managing UGS as areas potentially more burdened with contamination.

Isolation and Characterization of Strain Exiguobacterium sp. KRL4, a Producer of Bioactive Secondary Metabolites from a Tibetan Glacier

Extremophilic microorganisms represent a unique source of novel natural products. Among them, cold adapted bacteria and particularly alpine microorganisms are still underexplored. Here, we describe the isolation and characterization of a novel Gram-positive, aerobic rod-shaped alpine bacterium (KRL4), isolated from sediments from the Karuola glacier in Tibet, China. Complete phenotypic analysis was performed revealing the great adaptability of the strain to a wide range of temperatures (5-40 °C), pHs (5.5-8.5), and salinities (0-15% w/v NaCl). Genome sequencing identified KRL4 as a member of the placeholder genus Exiguobacterium_A and annotation revealed that only half of the protein-encoding genes (1522 of 3079) could be assigned a putative function. An analysis of the secondary metabolite clusters revealed the presence of two uncharacterized phytoene synthase containing pathways and a novel siderophore pathway. Biological assays confirmed that the strain produces molecules with antioxidant and siderophore activities. Furthermore, intracellular extracts showed nematocidal activity towards C. elegans, suggesting that strain KRL4 is a source of anthelmintic compounds.

Hydrochemical composition, distribution, and sources of typical organic pollutants and metals in Lake Bangong Co, Tibet

Lake Bangong Co is a special lake in western Tibet, with characteristics of increased salinity from the eastern area to the western area. Due to its remote location and poor environmental conditions, there are few background data on the water environment of this lake. In this study, the water chemical composition of Lake Bangong Co was studied, and the concentration levels, distribution characteristics, and pollution sources of polycyclic aromatic hydrocarbons (PAHs), phthalic acid esters (PAEs), and metals (As, Pb, Cr, Mn, Cu, Cd, Ni, and Zn) were investigated. The hydrochemical characteristics of the lake showed significant spatial differences. Conductivity, salinity, degree of mineralization, total hardness, Cl^-, and SO₄^2- generally increased from the eastern part to the western part. Most water quality parameters met the class III standards of the Chinese surface water standards; however, the Cl^- and SO₄^2- concentrations in the western part exceeded the surface water standard limits. ΣPAH and ΣPAE concentrations in lake water have no significant relationship with hydrochemical parameters. Among the 16 target PAHs, 4 PAH monomers with a (5 + 6)-ring were not detected in the lake water. The main sources of PAHs included emissions from biomass combustion, petroleum volatilization, and automobile exhaust. Six PAE monomers were detected at all sampling sites with relatively low concentrations, and di-2-ethylhexyl phthalate (DEHP) and di-n-butyl phthalate (DBP) were the main pollutants. The main source of PAEs was domestic waste, which might be related to increasing human activities in this area recently. In general, the concentrations of metals in the water of Lake Bangong Co were lower than those in the regions affected by anthropogenic activities except As. The results of PCA showed that As, Cu, and Cr mainly originated from natural sources; Pb, Mn, and Cr came from both natural and anthropogenic sources; and Cd was highly likely from anthropogenic sources.

Distribution, pollution, bioaccumulation, and ecological risks of trace elements in soils of the northeastern Qinghai-Tibet Plateau

Environmental quality of the northeastern Qinghai-Tibet Plateau has attracted more attention due to increasing anthropogenic disturbance. Therefore, this study investigated the distribution, pollution, ecological risks, and bioaccumulation of 12 target heavy metals and 16 rare earth elements (REEs) in soils of this area. The average concentrations of target trace elements in soils ranged from 0.16 (Hg) to 500.46 (Cr) mg/kg. Pb caused more serious pollution than the other elements based on geo-accumulation index evaluation. Hg exhibited the strongest enrichment feature with the average enrichment factor of 8.41. Compare with modified contamination degree and pollution load index, Nemerow pollution index method obtained the most serious evaluation results that 45.67% and 16.54% of sampling sites possessed high and moderate pollution. Evaluation results of potential ecological risk index showed that trace elements in soils posed very high and considerable ecological risks in 34.65% and 7.09% of sampling sites, respectively. Mining area was the region with the most serious pollution and ecological risks. Average bioaccumulation factor (BCF) values of target trace elements ranged from 0.05 (REEs) to 2.67 (Cr). Cr was the element that was easier to bio-accumulate in plants of the study area than the other target elements. It is in urgent need to take effective measures for controlling current pollution and potential ecological risks of trace elements in soils of the northeastern Qinghai-Tibet Plateau.

Physio-biochemical and molecular mechanism underlying the enhanced heavy metal tolerance in highland barley seedlings pre-treated with low-dose gamma irradiation

Heavy metal pollution, as a consequence of rapid industrialization and urbanization, poses a threat to highland barley grown in Tibet. This study investigates the effect of different doses of gamma irradiation (50–300 Gy) on the physio-biochemical and molecular mechanism of highland barley under heavy metal stress. Growth data showed that 50-Gy gamma irradiation had the maximal beneficial effects on the highland barley seedlings under lead/cadmium stress. The results of oxidative parameters demonstrated that 50-Gy gamma-irradiated seedlings had lower hydrogen peroxide and malondialdehyde contents under lead/cadmium stress compared to non-irradiated seedlings. Moreover, the activities of antioxidant enzyme and proline levels in 50-Gy gamma-irradiated seedlings were drastically higher than those in non-irradiated seedlings under lead/cadmium stress. Additionally, transmission electron microscopy results revealed that the 50-Gy gamma-irradiated seedlings exhibited improved chloroplasts ultrastructure compared with non-irradiated seedlings exposed to lead/cadmium stress. Notably, transcriptional expression analysis showed that 50-Gy gamma irradiation could significantly affect the expression of genes related to heavy metal transport and abscisic acid metabolism under lead/cadmium stress. Collectively, these results provide insights into the physio-biochemical and molecular mechanisms of low-dose-gamma-irradiation-enhanced heavy metal tolerance in highland barley seedlings, thus proposing gamma irradiation as a potential technology to mitigate heavy metal toxicity in crops.

Risk assessment of heavy metals in soil of Tongnan District (Southwest China): evidence from multiple indices with high-spatial-resolution sampling

Assessment of heavy metal (HM) pollution in soil is critical for human health, ecological remediation, and soil conservation. In this study, statistical analyses and geochemical approaches such as enrichment factor (EF), the index of geoaccumulation (Igeo), and potential ecological risk index (RI) were used for characterization and risk assessment of soil HMs through a high-spatial-resolution 385 samples from Tongnan District, an important agricultural practice area in Chongqing Municipality in Southwest China. Igeo and EF indicated that Hg and Cd could be considered as low and moderate polluted, respectively, and others HMs were not a major concern. Comprehensive ecological risk information further demonstrated that the HMs have caused a moderate risk. Principal component analysis (PCA) extracted two principal components (PCs) with eigenvalue >1 explaining about 66.1% of the total variance in the HM data sets, demonstrating major source of anthropogenic activity, phosphate fertilizers, vehicle, and pesticides. These multi-index methods have the capacity of HM assessment in soil, which are useful for soil conservation and ecological remediation.

Potentially toxic trace element contamination, sources, and pollution assessment in farmlands, Bijie City, southwestern China

Artisanal zinc smelting activities, which had been widely applied in Bijie City, Guizhou Province, southwestern of China, can pollute surrounding farmlands. In the present study, 177 farmland topsoil samples of Bijie City were collected and 11 potentially toxic trace elements (PTEs), namely Pb, Zn, Cu, Ni, Co, Mn, Cr, V, Hg, As, and Cd were tested to characterize the concentrations, sources, and ecological risks. Mean concentrations of these PTEs in soils were (mg/kg) as follows: Pb (127), Zn (379), Cu (93.1), Ni (54.6), Co (26.2), Mn (1095), Cr (133), V (206), Hg (0.15), As (16.2), and Cd (3.08). Pb, Zn, and Cd had coefficients of variation greater than 100% and showed a high uneven distribution and spatial variability in the study area. Correlation coefficient analysis and principal component analysis (PCA) were used to quantify potential pollution sources. Results showed that Cu, Ni, Co, Mn, and V came from natural sources, whereas Pb, Zn, Hg, As, and Cd came from anthropogenic pollution sources. Geoaccumulation index and potential ecological risk indices were employed to study the pollution degree of PTEs, which revealed that Pb and Cd shared the greatest contamination and would pose serious ecological risks to the surrounding environment. The results of this study could help the local government managers to establish pollution control strategies and to secure food safety.

Spatial Eco-Risk Assessment of Heavy Metals in the Surface Soils of Industrial City of Aran-o-Bidgol, Iran

Heavy metals usually accumulate and migrate in soil environment due to human activities and this in return poses potential ecological and health risks. A total of 135 surface soil samples were collected from Aran-o-Bidgol City, Iran and were analyzed for their Cd, Pb, Ni and Cu concentrations to determine these elements' spatial distribution and potential ecological risks. To this end, interpolation mapping was conducted using Ordinary Kriging. The mean concentrations of Cd, Pb, Ni and Cu in the samples were 0.72, 11.41, 29.87 and 14.82 mg kg(-1), respectively, which were all higher than their background values. The spatial variation in the concentration of heavy metals could be attributable to point sources and vehicle emissions. Considering the severity of the potential ecological risks of metals, the descending order of contaminants' concentrations was Cd > Cu > Ni > Pb. The Potential Ecological Risk Index (RI) suggested that approximately 40 % and 59 % of the samples posed high and significantly high potential ecological risks, respectively. Moreover, ecological risk decreased progressively going from southwest to northeast over the under-study area. Considering the background values and RI, this area presented a relatively high level of contamination.

Health risks of metals in contaminated farmland soils and spring wheat irrigated with Yellow River water in Baotou, China

The consumption of water and food crops contaminated with metals is a major food chain route for human exposure. We investigated the health risks of metals in Yellow River (YR) water, farmland soil and spring wheat in the Baotou region, northern China. Data indicated that long-term irrigation with polluted YR water led to metal accumulation in local farmland soil and spring wheat. The consumption of YR water and spring wheat in Baotou region can cause adverse health effects to local people, specifically because of Hg, Pb, and Se in YR water and Cu, Zn, Cd, and Mn in spring wheat. The integrative risk of various metals depends mainly on the spring wheat intake. Current results emphasized the need for routine monitoring and management in order to avoid contamination of YR water and spring wheat from the wastewater irrigation system in Baotou region.