Spatial distribution of harmful trace elements in Chinese coalfields: An application of WebGIS technology

Anthropogenic processes drive spatiotemporal variability of sulfate in groundwater from a multi-aquifer system: Dilution caused by mine drainage

The water quality evolution of surface and groundwater caused by mining activities and mine drainage is a grave public concern worldwide. To explore the effect of mine drainage on sulfate evolution, a multi-aquifer system in a typical coal mine in Northwest China was investigated using multi-isotopes (δ34SSO4, δ18OSO4, δD, and δ18Owater) and Positive Matrix Factorization (PMF) model. Before mining, the Jurassic aquifer was dominated by gypsum dissolution, accompanied by cation exchange and bacterial sulfate reduction, and the phreatic aquifers and surface water were dominated by carbonate dissolution. Significant increase in sulfate in phreatic aquifers due to mine drainage during the early stages of coal mining. However, in contrast to common mining activities that result in sulfate contamination from pyrite oxidation, mine drainage in this mining area resulted in accelerated groundwater flow and enhanced hydraulic connections between the phreatic and confined aquifers. Dilution caused by the altered groundwater flow system controlled the evolution of sulphate, leading to different degrees of sulfate decrease in all aquifers and surface water. As the hydrogeochemical characteristic of Jurassic aquifer evolved toward phreatic aquifer, this factor should be considered to avoid misjudgment in determining the source of mine water intrusion. The study reveals the hydrogeochemical evolution induced by mine drainage, which could benefit to the management of groundwater resources in mining areas.

Receptor model-based source-specific health risks of toxic metal(loid)s in coal basin-induced agricultural soil in northwest Bangladesh

Toxic metal(loid)s (TMLs) in agricultural soils cause detrimental effects on ecosystem and human health. Therefore, source-specific health risk apportionment is very crucial for the prevention and control of TMLs in agricultural soils. In this study, 149 surface soil samples were taken from a coal mining region in northwest Bangladesh and analyzed for 12 TMLs (Pb, Cd, Ni, Cr, Mn, Fe, Co, Zn, Cu, As, Se, and Hg). Positive matrix factorization (PMF) and absolute principal component score-multiple linear regression (APCS-MLR) receptor models were employed to quantify the pollution sources of soil TMLs. Both models identified five possible sources of pollution: agrochemical practice, industrial emissions, coal-power-plant, geogenic source, and atmospheric deposition, while the contribution rates of each source were calculated as 28.2%, 17.2%, 19.3%, 19% and 16.3% in APCS-MLR, 22.2%, 13.4%, 24.3%, 15.1% and 25.1% in PMF, respectively. Agrochemical practice was the major source of non-carcinogenic risk (NCR) (adults: 32.37%, children: 31.54%), while atmospheric deposition was the highest source of carcinogenic risk (CR) (adults: 48.83%, children: 50.11%). NCR and CR values for adults were slightly higher than for children. However, the trends in NCR and CR between children and adults were similar. As a result, among the sources of pollution, agrochemical practices and atmospheric deposition have been identified as the primary sources of soil TMLs, so prevention and control strategies should be applied primarily for these pollution sources in order to protect human health.

Effects of water-coal interactions on coal mine water quality in China: a lixiviation experiment and actual water quality investigation

Water-coal interactions are dominant factors that affect water quality in coal mines. Using lixiviation, the effects of water-coal interactions on pH, salinity, and hazardous elemental enrichment in coal mine water and associated trends were simulated and analyzed. The salinity and hazardous element contents were low in the alkaline solution filtrate. However, the salinity and contents of hazardous elements (As, Cr, Zn, Cu, Mn, Co, Ni, Cd, Pb, U, and Be) in acid solution filtrate increased significantly with a decrease in pH. The pH of the solution filtrate was affected by the mineral composition of the coal, wherein the pyrite content could generally determine the pH. In addition, the spatial distribution and utilization potential of coal mine water quality in China was determined based on water quality data surveys. For water-deficient regions in northern China, particularly in the northwest, the local mine water had high salinity, a high pH, and a low content of hazardous elements; therefore, the reuse of mine water for water consumption is feasible. Conversely, the mine water in the southwest region had high salinity and a low pH and was enriched in harmful elements with potential ecological and health risks. The actual water quality characteristics of the coal mine water matched the results of the laboratory simulation analysis, confirming the effect from water-coal interactions. This work provides a reference for understanding the determinants of coal mine water quality and the potential for water environment protection.

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.

Chromium in Chinese coals: geochemistry and environmental impacts associated with coal-fired power plants

Chromium (Cr), one of the prime hazardous trace elements in coals, may engender adverse effects on eco-environment and threaten human health during utilization of coal. Based on the samples obtained in our laboratory and published literature, the abundance and modes of occurrence of Cr in Chinese coals, and the environmental impacts associated with coal-fired power plants (CFPPs) were elucidated in this study. With a total of 1397 sets of data, the mean concentration of Cr in Chinese coals was calculated as 21.33 μg/g by the "reserve-concentration" weighted calculation method. Spatially, the average Cr contents increased gradually from North China to South China. Temporally, coals from T₃, E-N and P₂ were relatively enriched in Cr compared to the other geological time. The Cr concentration in coal varied with different coal ranks. The geological factors accounted for Cr enrichment in coals could be divided into the primary, secondary and epigenetic processes. Higher percentages of organically Cr occurred in low-rank coals, while inorganically associated Cr was mainly found in clay minerals. After coal combustion, most of Cr was enriched in solid wastes (e.g., fly ash and bottom ash). The leaching of Cr from solid wastes in the rainy season (especially acid rain) needs to be a concern for CFPPs. It was estimated that the atmospheric emission of Cr from CFPPs increased annually from 2015 to 2019 and reached approximately 159 tons in 2019.

Geochemistry of Late Permian coals from the Yueliangtian coal deposit, Guizhou: Evidence of sediment source and evaluation on critical elements

The enrichment of rare, scattered, rare earth, and noble elements, such as Li, Ga, Ge, rare earth elements and yttrium (REY), platinum group elements (PGE), Au, and Ag, have been discovered in the Late Permian coals from southwestern China. With the gradual depletion of traditional ore deposits, the geochemistry and resource utilization of critical metals in coals have received considerable attention. The geochemistry of associated elements in the Late Permian coals from the No. 10 coal profile of the Yueliangtian (YLT) underground mine, Liupanshui coalfield in Guizhou, were investigated to reveal the sediment source of inorganic components, as well as utilization prospects and controlling factors of critical metals. Silver and Pb were slightly enriched in the Yueliangtian coals, while Be, Rb, Sr, Mo, Cs, Ba, Tl, Bi, and U were significantly lower than that of world hard coals. The concentrations of total REY and individual elements in the Yueliangtian coals were similar to those of world hard coals. The minerals kaolinite, pyrite, calcite, and quartz predominated in coals, with trace amounts of anatase, gypsum, and apatite. High anatase proportion was identified in the floor and roof rock samples. Based on the Al₂O₃/TiO₂ and Zr/TiO₂ versus Nb/Y ratios, elemental assemblages, REY distribution, and paleogeography, the sediment source of mineral matter in the Yueliangtian coals dominated by felsic-intermediate rocks that from a distal volcanic arc or orogens was inferred. The terrigenous debris in the roof and floor rocks primarily originated from the high-Ti basalt of the Emeishan Large Igneous Province (ELIP). The relatively low elemental concentrations in these coals were primarily determined by their sediment sources. Although most critical metals in this coal were not enriched, the concentration of REY in coal ash was high enough to be considered as a potential resource for REY recovery given the extremely low ash yields of this coal.

Dissolution of harmful trace elements from coal and the environmental risk to mine water utilization

Under the pressure of water shortages, coal mine water has been allocated as a national water resource in China. However, the existence of harmful trace elements (HTEs) in coal mine water causes environmental risks and health concerns over its reuse. Through a lixiviation experiment, the dominant factors affecting the dissolution of HTEs in coal were simulated and analyzed, and the environmental risks of HTEs in coal mine water in China were evaluated for the first time. The average dissolved content levels of HTEs from coal were Mn > Cu > Zn > Ni > Ba > Cr > Co > V > Mo > Se > U > Pb > Cd, and the average maximum dissolution rates were Ni > Co > Mo > Zn > Cu > Cd > Mn > Se > Ba > Cr > U > Pb > V. Oxidation-reduction potential (Eh) and pH are the dominant factors controlling HTE dissolution. Higher oxygen exposure levels induce Eh and pH development, resulting in more HTE dissolution. This study constructed the dissolution potential index (F_C) of HTEs from coal. Based on the results of the F_C model, the areas with the highest migration potential and environmental risk of HTEs from coal seams to mine water are located in southern China, especially in the southwest, followed by areas of eastern Inner Mongolia and Shanxi and Shaanxi provinces. The corresponding risks in other regions are relatively low; thus, mine water utilization remains an effective option. This study provides an effective reference for the analysis of HTE enrichment in coal mine water and an evaluation of its safe utilization.

Dietary and drinking water intake of essential trace elements in a typical Kashin-Beck disease endemic area of Tibet, China

BACKGROUND

Essential trace elements (ETEs), such as copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), zinc (Zn), are very important elements for human health.

METHODS

In this study, 89 drinking water samples and 85 highland barleys were collected from 48 villages in 11 townships, and the average daily dose (ADD) of ETEs were calculated, in addition, health effects of ETEs to rural residents in Luolong County, a typical Kashin-Beck disease (KBD) endemic area in Tibet, were assessed.

RESULTS

The mean concentrations of Cu, Fe, Mn, Mo, Se, Zn in drinking water were 0.278 ± 0.264 μg·kg^-1, 0.766 ± 0.312 μg·kg^-1, 0.411 ± 0.526 μg·kg^-1, 0.119 ± 0.223 μg·kg^-1, 0.155 ± 0.180 μg·kg^-1, and 0.804 ± 1.112 μg·kg^-1, respectively; and mean concentrations of Cu, Fe, Mn, Mo, Se and Zn in highland barley were 3.550 ± 0.680 mg·kg^-1, 81.17 ± 38.14 mg·kg^-1, 14.03 ± 1.42 mg·kg^-1, 0.350 ± 0.200 mg·kg^-1, 0.0028 ± 0.0056 mg·kg^-1, and 23.58 ± 3.10 mg·kg^-1, respectively. The ADD of Cu in the study area was appropriate; the ADD of Fe and Mn in each township were higher than the maximum oral reference dose recommended by the National Health Commission of China, indicating that Fe and Mn had non-carcinogenic health risks; the ADD of Mo and Zn in 36.36% and 54.55% of the townships exceeded the maximum oral reference dose; and 72.73% of the townships had insufficient ADD of Se. The ADD of Mo, Cu and Se in different townships was significantly correlated with the prevalence of KBD.

CONCLUSIONS

Therefore, in order to prevent and control the prevalence of KBD and ensure the health of local residents, it is necessary to reduce the intake of high concentrations of Fe, Mn and Zn in diet, as well as increase the intake of Mo, Cu, especially Se.

Contamination, sources and health risks of toxic elements in soils of karstic urban parks based on Monte Carlo simulation combined with a receptor model

Understanding the health risks of toxic elements (TEs) in urban park soils and determining their priority control factors are crucial for public health and pollution management. Soil samples were collected from 33 urban parks in Guiyang, a typical karstic city. For each park, 15-45 topsoil samples were collected according to the area and then thoroughly mixed to obtain a representative sample. The results showed that the mean concentrations of TEs in park soils (22.5, 0.37, 88.6, 43.7, 0.26, 39.9, 44.7, and 101.0 mg/kg for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, respectively) were higher than their background values. Approximately 54.5% and 33.3% of enrichment factor (EF) values reached moderately enriched to significantly enriched levels for Cd and Hg, respectively. Moreover, 54.5% and 42.4% of monomial potential ecological index (EI) values were at considerable to high risk levels for Cd and Hg, respectively. These results illustrate that Cd and Hg pose high ecological risks. According to the potential ecological risk index (RI) values, 21.2% of the parks were exposed to considerable ecological risk and 48.5% were at moderate risk. Based on the positive matrix factorization (PMF) model, four sources governing TE contamination (including coal combustion, natural sources, traffic emissions, and industrial activities) were identified, with contribution rates of 32.3%, 31.0%, 19.6%, and 17.1%, respectively. A probabilistic health risk assessment showed acceptable non-carcinogenic risks and high levels of carcinogenic risk in all populations. Based on the source-specific health risk assessment, arsenic from coal combustion was determined to be a major contributor to human health risks. Although several efforts have been made by the local government to eliminate coal-borne arsenicosis, our results revealed that the accumulation of arsenic in the soil due to coal combustion poses a potential threat to human health.

Data Visualization and Interaction of Urban Traffic Logistics Management System Using WebGIS

At present, the large amount of data generated by transportation and logistics in cities brings great difficulties to data management and operation. The purpose is to explore the applicability of WebGIS and expand the application of intelligent interactive urban traffic logistics management. An urban traffic logistics management system is designed for urban traffic route assignment and intelligent interaction based on the WebGIS system and the basic principles and related algorithms of urban traffic route assignment. Then, the operation of the system under different shortest path algorithms and different path assignment algorithms is discussed. As a result, the Dijkstra algorithm runs faster than the Floyd algorithm. The comparison of three different road assignment algorithms shows that the no road assignment algorithm has the smallest average time consumption, which is 264.43 ms. The running time of the continuous average algorithm is the same as that of the user balance algorithm. The WebGIS system has practical application value compared with the TransCAD system and Cube system. This article proposes that the interactive function of the system can be used normally. The vehicle information of the test sample points can be displayed, and the function realization effect is good. The research results can provide scientific references for the follow-up research on intelligent transportation.

Uranium in Chinese coals: Concentration, spatial distribution, and modes of occurrence

Uranium in coals is an environmental radionuclide with resource utilization value. To comprehensively understand the prevalence of uranium in Chinese coals, the concentration, spatial distribution, and modes of occurrence were analyzed based on the data acquired from 1326 coal samples. Chinese coals are relatively rich in uranium, with the arithmetic and weighted average concentrations of 3.08 and 2.38 mg/kg, respectively. The regions with high uranium enrichment in coals are Guizhou, Guangxi, Yunnan, Sichuan and Chongqing, which are mainly located in southwestern China. The uranium was more enriched in Late Permian coal and medium-to-high metamorphic coal. Organic matter is the main carrier of uranium in coals, followed by silicates and sulfides. The factors affecting uranium enrichment in coal at the national scale include magma intrusions, volcanic ash, seawater influence, low-temperature hydrothermal fluids, and paleoclimate. This paper provides a reference for further research on environmental management and resource utilization of uranium in Chinese coals.

Emission and spatialized health risks for trace elements from domestic coal burning in China

Residential coal combustion (RCC) emission exhibited obvious daily variation, while no real-time estimation of air pollutants from RCC has been reported, as the shortages of corresponding activity dataset and emission factors with high time resolution. A real-time monitoring platform for RCC emission was established. Hourly emission factors of 18 typed of TEs from eleven kinds of chunk coals and nine kinds of honeycomb coals burning in China were obtained. The monthly and hourly coal consumption amounts were calculated with reference and our field survey. Then the hourly TEs emission inventories from RCC were established in China. GEOS-Chem and Risk Quotients Models were utilized to map the spatialized health risks of hazardous elements, including the gridded hazard index and carcinogenic risk. The result indicated that the EFs of TEs would be underestimated if the tests only consider flaming conditions. Cu, K, Ca, Zn, and Co were the top five elements from RCC, with corresponding emission amounts as 1397.7, 1054.0, 676.0, 623.5 and 420 tons in 2017, respectively. K, Ti, Fe, Sn, and Sb showed hourly peak values under flaming dominated periods, accounting for 48.2%, 45.9%, 31.8%, 42.8%, and 33.8% of their daily emissions. Other elements (e.g., V, Co, As, Hg and Pb) exhibited higher emissions under smoldering dominated period in nighttime, accounting for 22.2%, 32.9%, 27.6%, 34.7%, and 28.4% of their daily emissions. TEs emission from RCC closely follows the habits of human daily cooking and heating activity. The national HI were lower than the acceptable level (HI ≤ 1) except Sichuan Province (up to 1.2). Higher carcinogenic risks (≥1 × 10^-6) occurred in parts of Sichuan, Shanxi, Hunan and Hubei, which were up to 2.0 × 10^-5. The high-resolution TEs emission inventories could be useful for future modeling works on the formation and evolution of air pollution and are helpful for human exposure assessment.