Mine Vegetation Identification via Ecological Monitoring and Deep Belief Network.

Based on the characteristics of remote sensing images of mine vegetation, this research studied the application of deep belief network model in mine vegetation identification. Through vegetation identification and classification, the ecological environment index of mining area was determined according to the analysis of vegetation and coverage. Deep learning algorithm is adopted to improve the depth study, the vegetation coverage in the analysis was studied. Parameters and parameter values were selected for identification by establishing the optimal experimental design. The experimental results were compared with remote sensing images to determine the accuracy of deep learning identification and the effectiveness of the algorithm. When the sample size is 2,000,000 pixels, through repeated tests and classification effect comparison, the optimal parameter setting suitable for mine vegetation identification is obtained. Parameter setting: the number of network layers is 3 layers; the number of hidden layer neurons is 60. The learning rate is 0.01 and the number of iterations is 2. The average recognition rate of vegetation coverage was 95.95%, outperforming some other models, and the accuracy rate of kappa coefficient was 0.95, which can accurately reflect the vegetation coverage. The clearer the satellite image is, the more accurate the recognition result is, and the accuracy is closer to 100%. The identification of vegetation coverage has important guiding significance for determining the area and area of ecological restoration.

The elemental enrichments at Dajiuhu Peatland in the Middle Yangtze Valley in response to changes in East Asian monsoon and human activity since 20,000 cal yr BP.

Here we present multiproxy inorganic geochemical records from a peat core (ZK5) from the Dajiuhu Basin in central China to investigate peatland deposition processes and atmospheric metal pollution and to explore their relationships with East Asian monsoon change and human activities in the Middle Yangtze Valley since 20,000 cal yr BP. The peat physicochemical data including total organic carbon (TOC), trace elements, and grain-size show that the site has changed from a lake during the cold-wet Last Glacial Maximum (LGM; 20,000-18,000 cal yr BP), to a marshy wetland during the mild last deglaciation (18,000-11,500 cal yr BP) and a peatland during the mostly warm and dry Holocene (11,500 cal yr BP-present). This general sequence corresponds with changes in East Asian monsoon indicated by stalagmites δ18O records and boreal summer insolation. Marked decreases in trace element concentrations correspond to two periods of peatland expansion during the abrupt hydroclimatic transitions from the LGM to the last deglaciation and from the last deglaciation to the early Holocene. Warm-dry mid-Holocene might induce high organic matter decomposition in peat sediments. Increasing natural element concentrations since the late Holocene are correlated with the weakening of the summer monsoon and elevated atmospheric dust deposition. Increasing Cu and Pb concentrations in peat record indicate large-scale Cu smelting during the Bronze Age and excessive coal burning during the 10th century or so. The anthropogenic heavy metals were transported by prevailing East Asian summer monsoon and deposited in the Dajiuhu Basin during periods of heightened human activities. Our compilation of heavy metals records across China confirmed the noticeable impacts of the historical human activity on deposition environments during the late Holocene. Consequently, trace elements from the Dajiuhu Basin are reliable proxies for capturing monsoon climate-induced peatland deposition response and present important evidence for a historical atmospheric heavy metal pollution in the Middle Yangtze Valley. Our results offer useful references for peatland evolution and protection under the background of global change.

The origin of high hydrocarbon groundwater in shallow aquifer: experimental evidences from water-rock interaction.

The current studies had already revealed the hydrocarbons could migrate from relatively high hydrocarbon potential stratum to shallow groundwater by corrosion emission and extraction emission in karst area and further impact on human health. Then, the comprehensive experiments were used to understand the mechanism and process of hydrocarbon emission as a continuation of a long-term study on original high hydrocarbon groundwater in shallow Triassic aquifer, taking northwest Guizhou, China, as a reference. The results determined water-rock interaction that lead to the hydrocarbon emission into groundwater with salinity acting as the main driving force. Relatively high salinity promotes the rock corrosion and hydrocarbon emission in the study area. The hydrocarbon emission process varied with different strata, as the results show that the hydrocarbon uniformly distributed in T2g3 than that in T1yn4. Furthermore, the stratum with uniformly distributed hydrocarbon would likely contain high hydrocarbon groundwater, as determined by the process of sedimentation. In addition, "corrosion rate estimation method" and "mineral constituent estimation method" were firstly employed to estimate the hydrocarbon concentration in groundwater to date. Compared with the hydrocarbon concentration of local groundwater samples (0 to 0.14 mg L-1), the result of "mineral constituent estimation method" was analogous to measured value of groundwater samples in the area (0.05 to 0.50 mg L-1), indicating the concentration of hydrocarbon could be estimated by mineral constitutions of groundwater, which was related to the concentration of Ca2+ and Mg2+. Based on the methods and theories in this study, the concentration of original hydrocarbon in shallow groundwater could be estimated and help to understand the mechanism of water-rock interaction in shallow aquifer and original high hydrocarbon groundwater strategic assessment.

Spectral insight into thiosulfate-induced mercury speciation transformation in a historically polluted soil.

We studied the effect of different doses (0.5%, 2% and 5% (w/w)) of ammonium thiosulfate on mercury (Hg) speciation fractionation following its addition to the soil, as well as its accumulation by oilseed rape (Brassica napus L.), corn (Zea mays L.), and sweet potato (Ipomoea batatas L.), and compared them to a non-treated control in a historically polluted soil. The oilseed rape, corn, and sweet potato were planted consecutively in the same soils on days 30, 191, and 276, respectively after the addition of thiosulfate to the soil. The key results showed that bioavailable Hg contents in the rhizosphere soils ranged from 0.18 to 2.54 µg kg-1, 0.28 to 2.77 µg kg-1, and 0.24 to 2.22 µg kg-1, respectively, for the 0.5%, 2% and 5% thiosulfate treatments, which were close to the control soil (0.25 to 1.98 µg kg-1). The Hg L3-edge X-ray absorption near edge structure (XANES) results showed a tendency of the Hg speciation to transform from the Hg(SR)2 (initial soil, 56%; day-191 soil, 43%; day-276 soil, 46%, and day-356 soil, 16%) to nano particulated HgS (initial soil, 26%; day-191 soil, 42%; day-276 soil, 42%, and day-356 soil, 73%) with time in the soil treated with a 5% dose of thiosulfate. The Hg contents in the tissues of the crops, except for oilseed rape, were slightly affected by the addition of thiosulfate to the soil at all dosages, compared to the control. The addition of thiosulfate did not induce the movement of bioavailable Hg to the lower layer of the soil profile. We conclude a promotion of Hg immobilization by thiosulfate in the soil for over one year, offering a promising method for in-situ Hg remediation at Hg mining regions in China.

Dissimilatory arsenate-respiring prokaryotes catalyze the dissolution, reduction and release of arsenic from paddy soils into groundwater: implication for the effect of sulfate.

The paddy soils in some areas in Jianghan Plain were severely contaminated by arsenic. However, little is known about the activity and diversity of the dissimilatory arsenate-respiring prokaryotes (DARPs) in the paddy soils, and the effects of sulfate on the microbial mobilization and release of arsenic from soils into solution. To address this issue, we collected arsenic-rich soils from the depths of 1.6 and 4.6 m in a paddy region in the Xiantao city, Hubei Province, China. Microcosm assays indicated that all of the soils have significant arsenate-respiring activities using lactate, pyruvate or acetate as the sole electron donor. Functional gene cloning and analysis suggest that there are diverse DARPs in the indigenous microbial communities of the soils. They efficiently promoted the mobilization, reduction and release of arsenic and iron from soils under anaerobic conditions. Remarkably, when sulfate was amended into the microcosms, the microorganisms-catalyzed reduction and release of arsenic and iron were significantly increased. We further found that sulfate significantly enhanced the arsenate-respiring reductase gene abundances in the soils. Taken together, a diversity of DARPs in the paddy soils significantly catalyzed the dissolution, reduction and release of arsenic and iron from insoluble phase into solution, and the presence of sulfate significantly increased the microbial reactions.

[Distribution Characteristics and Health Risk Assessment of Heavy Metals in a Soil-Rice System in an E-waste Dismantling Area].

This study selected Guiyu Town, Guangdong Province as the research area, the content of 15 kinds of metals (As, Be, Cd, Co, Cr, Cu, Hg, Li, Mn, Ni, Sb, Sn, Pb, V, and Zn) in the soil was determined, and the content of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the rice of this research area was identified. Multivariate statistical analysis and a human health risk assessment model were used to investigate the distribution characteristics and health risk of heavy metals in a soil-rice system. The results showed that Hg, Sb, and Sn in the surface soil surrounding the electronic waste dismantling area have obvious accumulation effect. The average content of Cd and Hg exceeds the Ⅱ standard limit of the "Environmental Quality Standard for Soil" (GB 156182-1995), and that Guiyu Town is more seriously polluted than Chendian Town and Simapu Town. The multivariate statistical analysis showed that Cu, Sb, Ni, Zn, Sn, Pb, and Hg originated from the surrounding electronic waste dismantling activities, Cd and Be originated from other man-made sources of pollution, and V, Li, Cr, Co, As, and Mn originated from natural sources. Heavy metal evaluation concentration in the soil-rice system by heavy metal migration accumulated in rice are in compliance with national food hygiene standards, and the enrichment ability is Cd > Zn > Cu > Ni > As > Cr > Hg > Pb. Soil heavy metal health risk assessment results showed that children are more susceptible to heavy metal pollution, and handling-oral ingestion is the main way of soil exposure risk. The non-carcinogenic risk and carcinogenic risk of heavy metals in the soil of each town are acceptable. The health risk in Guiyu Town through ingestion of rice is mainly from the elements that include As, Cr, Cu, and Ni.

[Seasonal Characteristics and Ecological Risk Assessment of Heavy Metals in PM10 Around Electroplating Plants].

PM10 samples were collected from 45 sites around the electroplating factories in five towns in Dongguan at different times during all four seasons in 2015. The contents of 12 heavy metals (HMs) from the PM10 samples were analyzed by ICP-MS. The seasonal and spatial distribution characteristics and the ecological risk were analyzed to provide a scientific foundation for the relevant department to make decisions regarding the environmental hazard, risk assessment and, pollution control. The results showed that PM10 concentrations in the towns were lower than national standard level-Ⅱ, and the air pollution was heavier in winter than summer. The HM concentrations were higher in autumn and winter, and As, Cd, and Cr concentrations were higher than national standard (GB3095-2012). The concentrations of HMs in Humen, Shatian, and Dalingshan were much higher. The results for the enrichment factor and the geoaccumulation index indicated that Cd, Sb, Hg, and Co were in the extreme degree of pollution category, Pb and Zn were in the slight to extreme degree of pollution category, and Ni, Cr, Mn, and V were described as uncontaminated. The average potential ecological risk assessment (RI) of the HMs from the PM10 samples was more than 600, which suggested an extremely serious ecological risk in the study area.

[Distribution Characteristics and Health Risk Assessment of Metals in Drinking Water Sources from the Luhun Reservoir].

In order to investigate the distribution characteristics and the human health risks of 12 metals in drinking water sources from the Luhun Reservoir, Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, and Zn concentrations in 46 water samples collected from the reservoir in 2016 were measured and analyzed. The health risks caused by metals were assessed by using a human health risk assessment model. The results showed that the maximum concentration of Al (200.27 µg·L-1) and all concentrations of Mo (151.42-170.69 µg·L-1) in drinking water from the Luhun Reservoir exceeded the Environmental Quality Standards for Surface Water (GB 3838-2002) and Standards for Drinking Water Quality (GB 5749-2006) by 4.35% and 100%, respectively. A distinct spatial heterogeneity was found in the metal distribution, and the region with the highest metals concentrations was located southwest (upstream) and northeast (downstream) of the reservoir. The results of a health risk assessment indicated that children had greater health risks than adults. The health risks for metals through drinking were all higher than the values caused by dermal contact. Carcinogenic risks caused by Cr and As exceeded the maximum allowance levels (5×10-5 a-1) by 100% and 3.80%, respectively, and Cr accounted for 85% of the total carcinogenic risks. The non-carcinogenic risks of the metals (10-12-10-7 a-1) decreased in the order of Al > Mo > Cu > Pb > Ni > Hg > Fe > Zn > Mn, which had levels two to seven orders of magnitude lower than the maximum allowance levels.

The origin of high hydrocarbon groundwater in shallow Triassic aquifer in Northwest Guizhou, China.

Original high hydrocarbon groundwater represents a kind of groundwater in which hydrocarbon concentration exceeds 0.05 mg/L. The original high hydrocarbon will significantly reduce the environment capacity of hydrocarbon and lead environmental problems. For the past 5 years, we have carried out for a long-term monitoring of groundwater in shallow Triassic aquifer in Northwest Guizhou, China. We found the concentration of petroleum hydrocarbon was always above 0.05 mg/L. The low-level anthropogenic contamination cannot produce high hydrocarbon groundwater in the area. By using hydrocarbon potential, geochemistry and biomarker characteristic in rocks and shallow groundwater, we carried out a comprehensive study in Dalongjing (DLJ) groundwater system to determine the hydrocarbon source. We found a simplex hydrogeology setting, high-level water-rock-hydrocarbon interaction and obviously original hydrocarbon groundwater in DLJ system. The concentration of petroleum hydrocarbon in shallow aquifer was found to increase with the strong water-rock interaction. Higher hydrocarbon potential was found in the upper of Guanling formation (T2g3) and upper of Yongningzhen formation (T1yn4). Heavily saturated carbon was observed from shallow groundwater, which presented similar distribution to those from rocks, especially from the deeper groundwater. These results indicated that the high concentrations of original hydrocarbon in groundwater could be due to the hydrocarbon release from corrosion and extraction out of strata over time.

Risk Assessment and Source Identification of 17 Metals and Metalloids on Soils from the Half-Century Old Tungsten Mining Areas in Lianhuashan, Southern China.

Background: Mining activities always emit metal(loid)s into the surrounding environment, where their accumulation in the soil may pose risks and hazards to humans and ecosystems. Objective: This paper aims to determine of the type, source, chemical form, fate and transport, and accurate risk assessment of 17 metal(loid) contaminants including As, Cd, Cu, Ni, Pb, Zn, Cr, Ag, B, Bi, Co, Mo, Sb, Ti, V, W and Sn in the soils collected from an abandoned tungsten mining area, and to guide the implementing of appropriate remediation strategies. Methods: Contamination factors (CFs) and integrated pollution indexes (IPIs) and enrichment factors (EFs) were used to assess their ecological risk and the sources were identified by using multivariate statistics analysis, spatial distribution investigation and correlation matrix. Results: The IPI and EF values indicated the soils in the mine site and the closest downstream one were extremely disturbed by metal(loid)s such as As, Bi, W, B, Cu, Pb and Sn, which were emitted from the mining wastes and acid drainages and delivered by the runoff and human activities. Arsenic contamination was detected in nine sites with the highest CF values at 24.70 next to the mining site. The Cd contamination scattered in the paddy soils around the resident areas with higher fraction of bioavailable forms, primarily associated with intense application of phosphorus fertilizer. The lithogenic elements V, Ti, Ag, Ni, Sb, Mo exhibit low contamination in all sampling points and their distribution were depended on the soil texture and pedogenesis process. Conclusions: The long term historical mining activities have caused severe As contamination and higher enrichment of the other elements of orebody in the local soils. The appropriate remediation treatment approach should be proposed to reduce the bioavailability of Cd in the paddy soils and to immobilize As to reclaim the soils around the mining site. Furthermore, alternative fertilizing way and irrigating water sources are urgencies to reduce the input of Cd and As into the local soils effectively.

[Distribution Characteristics and Health Risk Assessment of Heavy Metals in Surface Water Around Electroplating Factories].

To investigate the distribution characteristics and the human health risks of heavy metals in surface water samples, 30 samples were collected around electroplating factories of Machong, Shatian, Humen, Changan and Dalingshan towns in Dongguan city, 8 heavy metals(As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) contents were measured and analyzed by using multivariate statistical analysis method and human health risk assessment model. The results showed that the maximum concentrations of Cr, Pb and the average concentration of Hg exceeded Environmental Quality Standards for Surface Water(GB 3838-2002, Grade Ⅲ), the concentrations of Cr, Cu, Hg, Ni, Zn and Pb during rainy season were all higher than that those during dry season. Multivariate statistical analysis indicated that Cd, Cr, Cu, Ni and Zn mainly originated from the contaminated electroplating factories, Pb and Hg were mainly affected by the traffic sources, and As was significantly correlated with natural sources. Health risk assessment result of surface water indicated that heavy metal pollution would lead to high health risks especially for children, and the health risks of heavy metals through drinking pathway were 2-3 orders of magnitude higher than the values caused by dermal contact pathway. Moreover, carcinogenic risks caused by Cr and As were higher than the maximum allowance levels (5×10-5 a-1), and non-carcinogenic risks of the heavy metals (10-10-10-7 a-1) decreased in the order of Pb > Ni > Cu > Hg > Zn, which were 4-5 orders of magnitude lower than the maximum allowance levels.

Levels and ecological risk assessment of metals in soils from a typical e-waste recycling region in southeast China.

Due to the high threat to human health and the ecosystem from metals, the levels and distribution of As, Hg, Cr, Co, Ni, Cu, Zn, Cd, Pb, Mn, V, Sn, Sb, Li and Be in various layers of soil from an e-waste recycling area in Guiyu, China were investigated. The extent of pollution from the metals in soil was assessed using enrichment factors (EFs) and the Nemerow pollution index (P N ). To determine the metals' integrated potential ecological risks, the potential ecological risk index (RI) was chosen. The concentrations of Hg, Ni, Cu, Cd, Pb, Sn and Sb were mainly enriched in the topsoil. EF values (2-5) of the elements Hg, Co, Ni, Zn, Sn, Li and Be revealed their moderate enrichment status in the topsoil, derived from e-waste recycling activities. P N presented a decreasing trend in different layers in the order topsoil (0-20 cm) > deep soil (100-150 cm) > middle soil (50-100 cm) > shallow soil (20-50 cm). With higher potential ecological risk factor (E(i)), Hg and Cd are the main contributors to the potential ecological risk. With respect to the RI, all the values in soil from the study area exceeded 300, especially for the soil at sites S2, S4, S5, S7 and S8, where RI was greater than 600. Therefore, immediate remediation of the contaminated soil is necessary to prevent the release of metals and potential ecological harm.