Concentrations, Distribution, Sources and Ecological Risk Assessment of Trace Elements in Soils from Wuhan, Central China

Bioindicator responses to extreme conditions: Insights into pH and bioavailable metals under acidic metal environments

Acid mine drainage (AMD) caused environmental risks from heavy metal pollution, requiring treatment methods such as chemical precipitation and biological treatment. Monitoring and adapting treatment processes was crucial for success, but cost-effective pollution monitoring methods were lacking. Using bioindicators measured through 16S rRNA was a promising method to assess environmental pollution. This study evaluated the effects of AMD on ecological health using the ecological risk index (RI) and the Risk Assessment Code (RAC) indices. Additionally, we also examined how acidic metal stress affected the diversity of bacteria and fungi, as well as their networks. Bioindicators were identified using linear discriminant analysis effect size (LEfSe), Partial least squares regression (PLS-R), and Spearman analyses. The study found that Cd, Cu, Pb, and As pose potential ecological risks in that order. Fungal diversity decreased by 44.88% in AMD-affected areas, more than the 33.61% decrease in bacterial diversity. Microbial diversity was positively correlated with pH (r = 0.88, p = 0.04) and negatively correlated with bioavailable metal concentrations (r = -0.59, p = 0.05). Similarly, microbial diversity was negatively correlated with bioavailable metal concentrations (bio_Cu, bio_Pb, bio_Cd) (r = 0.79, p = 0.03). Acidiferrobacter and Thermoplasmataceae were prevalent in acidic metal environments, while Puia and Chitinophagaceae were identified as biomarker species in the control area (LDA>4). Acidiferrobacter and Thermoplasmataceae were found to be pH-tolerant bioindicators with high reliability (r = 1, P < 0.05, BW > 0.1) through PLS-R and Spearman analysis. Conversely, Puia and Chitinophagaceae were pH-sensitive bioindicators, while Teratosphaeriaceae was a potential bioindicator for Cu-Zn-Cd metal pollution. This study identified bioindicator species for acid and metal pollution in AMD habitats. This study outlined the focus of biological monitoring in AMD acidic stress environments, including extreme pH, heavy metal pollutants, and indicator species. It also provided essential information for heavy metal bioremediation, such as the role of omics and the effects of organic matter on metal bioavailability.

The association of high-fluoride and high-iodine combined exposure with dental fluorosis and goiter: a meta-analysis

It is controversial that high-fluoride and high-iodine combined exposure affects the prevalence of dental fluorosis and goiter. The aim of this study was to explore the potential association between high-fluoride and high-iodine combined exposure with dental fluorosis and goiter. We retrieved relevant articles from PubMed, Cochrane Library, China National Knowledge Infrastructure, Wanfang Database and China Science and Technology Journal Database (VIP). The query format was 1 # "Fluorosis" OR "Fluoride," 2 # "Iodine" OR "Iodide," and 3 # 1 AND 2. A total of 20 papers were included in this study after independent review by two investigators. Our analysis showed that high-fluoride and high-iodine biphasic exposure was significantly associated with the prevalence of goiter (OR = 4.69, 95% CI 2.82-7.80, P < 0.001). The prevalence of dental fluorosis was also significantly raised (OR = 11.71, 95% CI 7.57-18.14, P < 0.001). Sensitivity analysis suggested that combined statistics of multiple studies were reliable. For goiter, subgroup analysis revealed study province, sample size and published year as sources of heterogeneity (P < 0.001). For dental fluorosis, only sample size was the impact factor of heterogeneity. As well, funnel plot, Begg's test and Egger's test suggested there was no publication bias (P > 0.05). Overall, our study demonstrates that high-fluoride and high-iodine combined exposure is a risk factor for occurrence of dental fluorosis and goiter. The chronic of high-fluoride and high-iodine combined exposure is a significant higher risk of disease than normal.

Potentially Toxic Element Contamination in Soils Affected by the Antimony Mine Spill in Northwest China

This study provides a comprehensive assessment of the potential ecological and health risks in the area of the antimony mine spill in Longnan, Northwest China, and identifies the sources of potentially toxic elements (PTEs) in the soil as a result of the spill. The geo-accumulation index and enrichment factor show that the study area is highly contaminated with arsenic (As), mercury (Hg) and antimony (Sb). The ecological risk index in the tailings spill area ranged from 320.43 to 5820.46 (mean: 1489.82), indicating a very-high potential ecological risk, with mean values of 104.86, 1118.87 and 248.84 for As, Hg and Sb, respectively. The multivariate statistical analysis suggested that Sb and Hg come from tailings leakage, while copper (Cu), nickel (Ni) and zinc (Zn) may be imported from natural sources, and As and lead (Pb) originate from agricultural activities. In addition As and Sb pose a high health risk. With the exception of the non-carcinogenic risk in adults, all other risks are significantly exceeded in other populations, with children being the highest-risk group. These findings provide important quantitative information for the assessment and management of PTE contamination in other tailings spill areas.

Pollution, Ecological Risk and Source Identification of Heavy Metals in Sediments from the Huafei River in the Eastern Suburbs of Kaifeng, China

Rivers in urban environments are significant components of their ecosystems but remain under threat of pollution from unchecked discharges of industrial sewage and domestic wastewater. Such river pollution, particularly over the longer term involving heavy metals, is an issue of worldwide concern regarding risks to the ecological environment and human health. In this study, we investigate the long-term pollution characteristics of the Huafei River, an important urban river in Kaifeng, China. River sedimentary samples were analyzed, assessing the degree and ecological risk of heavy metal pollution using the geo-accumulation index and potential ecological risk index methods, whilst Pearson's correlation, principal component and cluster analyses were used to identify the sources of pollution. The results show that heavy metal concentrations are significantly higher than their corresponding fluvo-aquic soil background values in China, and the geo-accumulation indexes indicate that of the eight heavy metals identified, Hg is most prevalent, followed in sequence by Cd > Zn > Cu > Pb > Ni > As > Cr. The potential ecological risk index of the Huafei River is very high, with the potential ecological risk intensity highest in the midstream and downstream sections, where it is recommended that pollution control is carried out, especially concerning Hg and Cd. Long-term sequence analysis indicates that Cu and Pb dropped sharply from 1998 to 2017, but rebounded in 2019, and that Zn shows a continuous decreasing trend. Four main sources for the heavy metal contaminants were identified: Cr, Cu, Ni, Pb, Zn and Hg derived mainly from industrial activities, traffic sources and natural sources; Cd originated mainly from industrial and agricultural activities; whilst As was mainly associated with industrial activities. Thus, special attention should be paid to Hg and Cd, and measures must be taken to prevent further anthropogenic influence on heavy metal pollution.

Glyphosate and glufosinate-ammonium in aquaculture ponds and aquatic products: Occurrence and health risk assessment

As the two most commonly used organophosphorus herbicides, glyphosate (Gly) and glufosinate-ammonium (Glu) have unique properties for weed control and algae removal in aquaculture. However, the occurrences and health risks of Gly and Glu in aquaculture ponds are rare known. This study aimed to investigate the occurrences of Gly, AMPA (primary metabolity of Gly) and Glu in surface water, sediment and aquatic products from the grass carp (ctenopharyngodon idella), crayfish (procambarus clarkii) and crab (eriocheir sinensis) ponds around Lake Honghu, the largest freshwater lake in Hubei province, China where aquaculture has become the local pillar industry. Three age groups (children, young adults, middle-aged and elderly) exposure to these compounds through edible aquatic products (muscle) consumption were also assessed by target hazard quotient (THQ) method. The results indicated that Gly, AMPA and Glu were widely occurred in surface water, sediment and organisms in the fish, crayfish and crab ponds. AMPA was more likely to accumulate in the intestine of aquatic products than Gly and Glu. According to the total THQ value (1.04＞1), muscle consumption of grass carp may pose potential risk to children.

Integrated assessment of major and trace elements in surface and core sediments from an urban lagoon, China: Potential ecological risks and influencing factors

Marine sediments serve as a sink for contaminants of anthropogenic origin. Here, 25 major and trace elements were determined in surface and core sediments from an urban lagoon (Yundang Lagoon), China. The median concentrations of Pb, Cd, Cu, and Zn in both surface and core sediments exceeded global and crustal averages. Principal component analysis for the elements and ecological impact of the heavy metals indicated spatial heterogeneity in core sediments from different lagoon areas; however, no such pattern was observed in surface sediments. Geodetector analysis indicated spatial locations of lakes, pH, N%, C%, and S% as the major factors influencing the heterogeneity of potential ecological risk index, a cumulative measure of the ecological impact of heavy metal. The interaction detector indicated nonlinear and bivariate enhancement between different physicochemical parameters. Besides, a depth profile of the elements in different samples was also elucidated.

Spatio-temporal distribution and source identification of heavy metals in particle size fractions of road dust from a typical industrial district

Seasonally distribution and source apportionment of Cr, Mn, Ni, Cu, Zn, Cd, and Pb in the road dust (RD) with the four size fraction sizes (<45 μm, 45-63 μm, 63-150 μm and all sizes) in a typical industrial district were investigated using a combination of Moran index, Principal component analysis (PCA), and Positive matrix factorization (PMF). Results showed that from winter to summer, the proportion of the <45 μm fraction dust in the total RD mass increased from 6.72% to 15.92% and that of 63-150 μm dust particles decreased from 31.13% to 21.76%. The proportion of the enrichment factors (EF) at moderate pollution level in winter was higher than that in summer, especially for Cu, Cd and Pb. Further, the heavy metals were relatively enriched in particles 63-150 μm in summer, while in particles <45 μm in winter. Spatially, the distribution of heavy metal concentrations was more concentrated in the winter and showed low levels of regional diffusion. Based on the pollution mapping and PCA-PMF, the integrated source appointment showed that the industrial sources are the main sources of Zn, Cd and Pb, and their contributions are higher at a particle below 45 μm in winter. The construction source significantly influenced Cr, Mn and Cu in summer with little diversity among particle size ranges. Therefore, the <45 μm particles from industrial emission in winter is suggested to be under priority control. And the industrial transformation demonstration area in the Qingshan district should upgrade heavy pollution industry lines and strengthen the monitoring of soot emissions. Further, emissions from coal-fired enterprises should be restricted in winter. Besides, the attention should be paid to avoid urban traffic jams around construction projects and increase enclosed construction ratio.

Pollution, Sources and Human Health Risk Assessment of Potentially Toxic Elements in Different Land Use Types under the Background of Industrial Cities

Residents in industrial cities may be exposed to potentially toxic elements (PTEs) in soil that increase chronic disease risks. In this study, six types of PTEs (Zn, As, Cr, Ni, Cu, and Pb) in 112 surface soil samples from three land use types—industrial land, residential land, and farmland—in Tonghua City, Jilin Province were measured. The geological accumulation index and pollution load index were calculated to assess the pollution level of metal. Meanwhile, the potential ecological risk index, hazard index, and carcinogenic risk were calculated to assess the environmental risks. The spatial distribution map was determined by the ordinary kriging method, and the sources of PTEs were identified by factor analysis and cluster analysis. The average concentrations of Zn, As, Cr, Ni, Cu, and Pb were 266.57, 15.72, 72.41, 15.04, 20.52, and 16.30 mg/kg, respectively. The results of the geological accumulation index demonstrated the following: Zn pollution was present in all three land use types, As pollution in industrial land cannot be neglected, Cr pollution in farmland was higher than that in the other two land use types. The pollution load index decreased in the order of industrial land > farmland > residential land. Multivariate statistical analysis divided the six PTEs into three groups by source: Zn and As both originated from industrial activities; vehicle emissions were the main source of Pb; and Ni and Cu were derived from natural parent materials. Meanwhile, Cr was found to come from a mixture of artificial and natural sources. The soil environment in the study area faced ecological risk from moderate pollution levels mainly contributed by As. PTEs did not pose a non-carcinogenic risk to humans; however, residents of the three land use types all faced estimated carcinogenic risks caused by Cr, and As in industrial land also posed high estimated carcinogenic risk to human health. The conclusion of this article provides corresponding data support to the government’s policy formulation of remediating different types of land and preventing exposure and related environmental risks.

Analysis of urinary trace element levels in general population of Wuhan in central China

Trace element distribution in the human body varies across regions and countries due to their different living environment and lifestyle. Thus, it is of great significance to investigate the reference level of trace element in a specific population. Wuhan is the largest metropolitan area in central China with highly developed heavy industries. This study aimed at determining the reference urinary distribution in general populations of Wuhan for nine trace elements (Cr, Mn, Cu, As, Se, Cd, Hg, Tl, Pb), and analyzed their associations with age, sex, and the kidney function. In total, 226 healthy adults not exposed to these trace elements were recruited, and the first-morning urine specimens were analyzed by using ICP-MS-based method. Our results showed higher urinary levels for As and Cd in Wuhan population when compared with other countries, while other element levels were almost equivalent. Sex difference existed for urinary Cu, Mn, As, Tl, and Pb. And urinary Cd, Tl, and Pb levels were associated with the glomerular filtration rate. Almost all these urinary elements showed significant inter-correlations, especially for Cu but except for Mn. This study provides systematic information regarding urinary trace element levels in residents of Wuhan in central China, and shall be of importance for future environmental and occupational biomonitoring.