A comprehensive approach to quantify the source identification and human health risk assessment of toxic elements in park dust.

In this research, enrichment factor (EF) and pollution load index were utilized to explore the contamination characteristics of toxic elements (TEs) in park dust. The results exhibited that park dust in the study area was mainly moderately polluted, and the EF values of dust Cd, Zn, Pb, Cu and Sb were all > 1. The concentrations of Cr, Cu, Zn and Pb increased with the decrease of dust particle size. The investigation results of chemical speciation and bioavailability of TEs showed that Zn had the highest bioavailability. Three sources of TEs were determined by positive matrix factorization model, Pearson correlation analysis and geostatistical analysis, comprising factor 1 mixed sources of industrial and transportation activities (46.62%), factor 2 natural source (25.56%) and factor 3 mixed source of agricultural activities and the aging of park infrastructures (27.82%). Potential ecological risk (PER) and human health risk (HHR) models based on source apportionment were exploited to estimate PER and HHR of TEs from different sources. The mean PER value of TEs in the park dust was 114, indicating that ecological risk in the study area was relatively high. Factor 1 contributed the most to PER, and the pollution of Cd was the most serious. There were no significant carcinogenic and non-carcinogenic risks for children and adults in the study area. And factor 3 was the biggest source of non-carcinogenic risk, and As, Cr and Pb were the chief contributor to non-carcinogenic risk. The primary source of carcinogenic risk was factor 2, and Cr was the cardinal cancer risk element.

A comprehensive exploration on the health risk quantification assessment of soil potentially toxic elements from different sources around large-scale smelting area.

Non-ferrous metal smelting activities have always been considered as one of the foremost anthropogenic sources of potentially toxic elements (PTEs). The enrichment factor (EF) and pollution load index (PLI) were used to evaluate the pollution level of soil PTEs; positive matrix factorization (PMF), correlation analysis, and geostatistics were utilized to quantify the sources of soil PTEs; and potential ecological risk (PER) and human health risk (HHR) of different sources from farmland, construction land, and natural land were quantifiably determined via combined PTE sources with PER and HHR assessment models. Taking the smelting area of Daye City as an example, the evaluation results of EF and PLI showed that the soil PTE pollution in the study area was serious, especially Cd and Cu. And four sources were quantitatively allocated as agricultural practices (12.14%), traffic emissions (23.07%), natural sources (33.46%), and industrial activities (31.33%). For PER, industrial activities were the largest contributor to PER, accounting for 55.66%, 56.30%, and 55.36% of farmland, construction land, and natural land, respectively, and Cd was the most dangerous element. In terms of HHR, industrial activities were also the cardinal contributors under the three land use types. Children were exposed to serious non-carcinogenic risks under three land use patterns and slight carcinogenic risk in construction land (1.06E - 04). Significantly, the carcinogenic risk of children in farmland (9.06 × 10-5) was very close to the threshold (1 × 10-4), which requires attention. Both non-carcinogenic and carcinogenic risk for adults were all at acceptable levels. The health risks (carcinogenic and non-carcinogenic risks) of children from four different sources were distinctly higher than those of adults. Consequently, strict management and control of industrial activities should be given priority, and the management of agricultural practices should not be ignored.

An integrated exploration on health risk assessment quantification of potentially hazardous elements in soils from the perspective of sources.

To make pollution evaluation of potentially hazardous elements in the soil more accurately, the regional geochemical baseline concentrations of eight potentially hazardous elements (Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb) were established in Huilai County using cumulative frequency distribution curves. Then, the pollution load index and enrichment factor were applied to estimate the contamination levels, based on these geochemical baseline concentrations. The results suggested that topsoil was moderately polluted by potentially hazardous elements, while Cd pollution in the construction land and As pollution in the farmland was relatively severe. The possible sources of eight potentially hazardous elements were analyzed by correlation analysis, geostatistics and positive matrix factorization. Four sources have been determined and apportioned, namely industrial activities, natural sources, agricultural practices, and traffic emissions. Combining the health risk assessment with the source profiles, the health risks quantified from four sources were estimated under farmland, construction land, and woodland. The results showed that agricultural practices were the most main source of non-cancer and cancer risks under woodland and farmland for adults; industrial activities were the most main source of non-cancer and cancer risks under construction land for adults. Children's health risks, both carcinogenic risk and non-carcinogenic risk, were greater than adults, and the health risk trends of adults and children showed similarities. Therefore, agricultural practices under woodland and farmland should be controlled and managed as a priority, while industrial activities should be given priority to control and management under construction land.

Heavy metals in agricultural soils from a typical township in Guangdong Province, China: Occurrences and spatial distribution.

To investigate contamination level, origins and spatial distribution characteristics of heavy metals (Cu, Pb, Zn, Hg, Ni, Cd, As, and Cr) in agricultural soils of Gaogang Town, a typical industrial transfer-undertaking region of the Pearl River Delta (PRD), China, a total of 162 surface soil samples were collected in August 2016 and determined using inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectrometry and atomic fluorescence spectrometry. Moreover, heavy metals contents were systematically analyzed by pollution index, enrichment factor, multivariate statistical approaches and geostatistical analysis. The results showed that the mean concentrations of Cd, Pb, Zn, Ni, Cu and Hg were higher than the soil background values of Guangdong Province, and the relatively high values of pollution index and enrichment factor indicated that these elements (Cd, Pb, Zn and Hg) had cumulative trends in soil. All results of multivariate statistical approaches and geostatistical analysis showed that pollution were heavily distributed in areas of industries, river and dense road network. The eight heavy metals in agricultural soils of Gaogang Town came from three different sources. Arsenic, Cr, Cu and Ni arose mainly from parent materials. Agricultural practices and traffic activities were the main sources of Cd, Pb and Zn. Mercury mainly came from industrial practices.

Mercury-Organic Matter Interactions in Soils and Sediments: Angel or Devil?

Many studies have suggested that organic matter (OM) substantially reduces the bioavailability and risks of mercury (Hg) in soils and sediments; however, recent reports have supported that OM greatly accelerates Hg methylation and increases the risks of Hg exposure. This study aims to summarize the interactions between Hg and OM in soils and sediments and improve our understanding of the effects of OM on Hg methylation. The results show that OM characteristics, promotion of the activity of Hg-methylating microbial communities, and the microbial availability of Hg accounted for the acceleration of Hg methylation which increases the risk of Hg exposure. These three key aspects were driven by multiple factors, including the types and content of OM, Hg speciation, desorption and dissolution kinetics and environmental conditions.

[Potential Ecological Risk Characteristics and Source Apportionment of Heavy Metals in Farmland Soils around Typical Factories in Hunan Province Based on Monte-Carlo Simulation].

In order to explore the pollution characteristics， ecological risks， and pollution sources of heavy metals in farmland soils around typical factories in Hunan Province， the content characteristics of eight heavy metals in farmland soils around fluoride factories， leather factories， and plating plants were analyzed. The geo-accumulation index and potential ecological risk index were used to evaluate the pollution and environmental risk of heavy metals. The correlation analysis， hierarchical cluster analysis， and principal component analysis were used to analyze the sources of heavy metals. The Monte-Carlo model was used to evaluate the probability risk of regional ecological risk. The results showed that the main pollution elements in the soil were Cd and Zn， and their mean values were 4.46 and 2.73 times the background values， respectively. Zn was at a mild pollution level in the soil of the three typical factories， and Cd was at a moderate pollution level in the whole fluoride factory. The pollution sources of heavy metals in the typical factories were mainly natural sources， industrial activity sources （industrial waste discharge， mineral mining， and smelting activities）， traffic sources， etc. The results of potential ecological risk assessment showed that the ecological risk of the fluoride factory was at a high risk level， and the ecological risk of the leather factory and plating plants was at a high risk level. Cd was the main contributing element. The results of Monte-Carlo probabilistic ecological risk assessment reduced the uncertainty of deterministic assessment， which could provide scientific basis for accurate risk management and control in the regions.

[Source Analysis and Risk Assessment of Heavy Metals in Soil of County Scale Based on PMF Model].

This study explores the pollution characteristics, risks, and sources of heavy metals in small-scale areas. Rongcheng District, Jieyang City, Guangdong Province was considered as the study area and enrichment factor (EF), pollution load index (PLI), potential ecological risk index (RI), and US EPA health risk assessment model were used to evaluate its environmental risk. Moreover, the source apportionment of heavy metals was analyzed through correlation analysis, the characteristic of spatial distribution, and a PMF model. The results showed that the mean concentrations of ω(Cr), ω(Hg), ω(As), ω(Pb), ω(Ni), ω(Cd), ω(Cu), and ω(Zn) were 54.87, 0.25, 8.35, 56.00, 15.38, 0.35, 30.56, and 124.23 mg·kg-1, respectively. The mean concentrations of all elements exceeded the local soil background value. In terms of EF level, Cr, As, Pb, and Ni showed negligible accumulation; Zn and Cu showed minor accumulation; and Hg and Cd showed moderate accumulation. The mean value of the pollution load index was 2.37, with a severe pollution level, and the eight elements were in different pollution levels. In total, the study region suffered severe ecological risk, Hg and Cd presented strong ecological risk, and other elements presented slight ecological risk. The non-carcinogenic risks under the three exposure paths were within the acceptable level. The carcinogenic risks (CR) of adults and children were 9.81E-05 and 5.59E-04, respectively, and Cr and As were the main contributors of CR. The results showed that the four sources of heavy metals were transportation sources (37.02%), parent material sources (18.53%), atmospheric deposition sources (26.49%), and industrial sources (17.96%).

A comprehensive exploration on pollution characteristics and health risks of potentially toxic elements in indoor dust from a large Cu smelting area, Central China.

Large-scale smelting activities release large amounts of potentially toxic elements (PTEs) in fine particles. These particles floating in the air eventually settle on leaves, roads, and even indoors. In smelting areas, indoor environments are generally considered relatively safe. However, these areas are not taken seriously and need to be assessed. This paper systematically studied pollution characteristics, main sources and health risks of ten potentially toxic elements, PTEs (Mn, Ni, Cu, Zn, Hg, Cd, As, Cr, Pb, and Tl), of dust samples from different indoor environments in smelting areas using various methods. Therefore, this study analyzed dust samples from 35 indoor environments. The enrichment factors showed that the indoor dust samples were extremely enriched by Cd and Cu and significantly enriched by Hg, Pb, As, and Zn. The result of the spatial distribution showed that the high-value PTEs were mainly distributed near the Cu smeltery. Three sources were quantitatively assigned for these PTEs, and they were industrial smelting and traffic activities (44.40%), coal-fired activities (18.11%), and natural existence (37.49%). Based on the calculation of health risk, the value of THI for children was 7.57, indicating a significant non-carcinogenic risk. For carcinogenic risk, the values of TCR for children and adults were 2.91×10-2 and 2.97×10-3, respectively, which were much higher than the acceptable risk value 1×10-4. Combining health risk assessment with source discrimination, we found that the industrial discharges and traffic activities were the most main source of non-cancer and cancer risks. Therefore, smelting activities should be more strictly monitored, and traffic emission management should be strengthened.

Characterizing pollution and source identification of heavy metals in soils using geochemical baseline and PMF approach.

It is necessary to establish local geochemical baseline concentrations (GBCs) due to the lack or the inapplicability of regional background values in the study area. The establishment of GBCs of heavy metal (HM) in soil helps in making the accurate assessment of pollution, and then provides a basis for pollution control. Based on this, a case study was undertaken to study the GBCs of the Jiedong District, Guangdong Province, China. In this research, cumulative frequency distribution curves were utilized to determine the local GBCs in the subsoils. The determined GBCs of Cr, Hg, As, Pb, Ni, Cd, Cu, Zn, Co and V were 39.91, 0.072, 11.48, 47.62, 12.70, 0.17, 14.22, 64.54, 6.31, and 68.14 mg/kg, respectively. The average concentrations of Hg, As, Pb, Cd, Cu and Zn in the topsoils exceeded the corresponding baseline concentrations. In particular, the contents of Cd and Hg were 1.53 and 2.22 times higher than GBCs. According to this baseline criterion, enrichment factor (EF), pollution load index (PLI) and ecological risk index (RI) were applied to assessing HM pollution. EF and PLI suggested that most areas were under moderate contamination, while Hg and Cd pollution was more serious. And the RI values presented that the potential ecological risks were low in most parts of the study area. The possible origins of HMs were identified by combining positive matrix factorization with EF and geostatistics. Comprehensive analysis indicated that Hg and Cd were related to industrial activities, such as textile and garment processing, plastic and rubber production and metal manufacturing. Arsenic and part of Cu mainly came from agricultural activities, namely the use of pesticides, fertilizers and livestock manures. Lead and Zn were mainly attributed to traffic emissions. Chromium, Ni, V, Co, and part of Cu were originated from natural source controlled by parent materials. The corresponding contributions of these sources were 20.61%, 24.20%, 19.22% and 35.97%, respectively. This work provides information to prevent and control the soil HM pollution by proposing the efficient management of anthropogenic sources.

An integrated approach to quantifying ecological and human health risks from different sources of soil heavy metals.

Heavy metals (HMs) in soil cause adverse effects on ecosystem and human health. Quantifying ecological risk and human health risk (HHR) from sources can determine priority sources and help to mitigate the risks. In this research, geostatistics and positive matrix factorization (PMF) were used to identify and quantify the sources of soil HMs; and then ecological risk and HHR from different sources under woodland, construction land and farmland were quantitatively calculated by combining the potential ecological risk index (RI) and HHR assessment models with PMF model. Taking Jiedong District as an example, four sources were quantitatively apportioned, which were agricultural practices (23.08%), industrial activities (29.10%), natural source (22.87%) and traffic emissions (24.95%). For ecological risk, industrial activities were the greatest contributor, accounting for about 49.71%, 48.11% and 47.15% under construction land, woodland and farmland, respectively. For non-carcinogenic risk, agricultural practices were the largest source under woodland and farmland, while industrial activities were the largest source under construction land. As for carcinogenic risk, no matter which kind of land use, agricultural practices were the largest source. In addition, the health risks of children, including non-carcinogenic and carcinogenic risks, were higher than those of adults, and the trends in health risks for children and adults were similar. The integrated approach was useful to evaluate ecological risk and HHR quantification from sources under different land use, thereby providing valuable suggestions for reducing pollution and protecting human health from the sources.

MicroRNA-277 regulates dopa decarboxylase to control larval-pupal and pupal-adult metamorphosis of Helicoverpa armigera.

Insect metamorphosis is a complex process involving many metabolic pathways, such as juvenile hormones and molting hormones, bioamines, microRNAs (miRNAs), etc. However, relatively little is known about the biogenic amines and their miRNAs to regulate cotton bollworm metamorphosis. Here we show that one miRNA, miR-277 regulates larval-pupal and pupal-adult metamorphosis of cotton bollworm by targeting the 3'UTR of Dopa decarboxylase (DDC), a synthetic catalytic enzyme of dopamine. Injection of miR-277 agomir inhibited the expression of DDC at the mRNA and protein levels, leading to defects in the pupation and emergence of H. armigera that was consistent with the phenotype obtained by injection of DDC double-stranded RNA (dsRNA). Injection of miR-277 antagomir induced the mRNA and protein expression of DDC and rescued the phenotype of pupation failure caused by DDC gene silencing. Unexpectedly, miR-277 antagomir can also cause failure of emergence of H. armigera and both agomir and antagomir of miR-277 injection could cause abnormal phenotypes in wing veins. This study reveals that elaborate regulation of miRNA and its target gene expression is prerequisite for insect development, which provides a new insight to study the developmental mechanisms of insect wing veins.

Metals in soils from a typical rapidly developing county, Southern China: levels, distribution, and source apportionment.

A total of 321 surface soil samples were collected from Huilai County, Guangdong Province, Southern China. Concentrations of 12 metals (Cr, Hg, As, Pb, Ni, Cd, Cu, Zn, Sb, Sn, Ti, and V) were measured. The mean concentrations of As, Pb, Cd, Zn, Sn, and Ti were higher than their corresponding soil background values, especially for As, Cd, and Sn, which were 1.36, 2.50, and 2.77 times of the background values, respectively. And the results of enrichment factor and pollution load index suggested that soil metals in the study area were moderately contaminated, but pollution of As, Cd, and Sn was relatively serious. According to one-way analysis of variance, there were significant differences in concentrations of Hg, As, Pb, Cd, Zn, and Sn between different land use types, indicating that they were associated with the anthropogenic inputs. The potential sources of metals were quantitatively apportioned by positive matrix factorization, and combined with correlation analysis and geostatistical. The results showed that Cr, Ni, Ti, and V mainly originated from natural sources. Lead, Zn, and partially, Cd mainly came from traffic emissions. Arsenic, Cu, and partially, Sb were ascribed to agricultural practices. Mercury, Sn, partially, Cd, and Sb were derived from industrial activities. Their corresponding contributions were 36.88%, 22.14%, 20.87%, and 20.11%, respectively.

Heavy metal contamination and health risk assessment for children near a large Cu-smelter in central China.

Nonferrous metallurgy is causing significant concerns due to its emissions of heavy metals into environment, degrading environmental quality, and consequently posing high risks to human health. In this study, the concentration levels of Cadmium (Cd), Copper (Cu), Lead (Pb), and Arsenic (As) were investigated in soil, crop, well water, and fish samples collected around the Daye Copper Smelter in Hubei province, China, and the potential health risks were assessed for local children. The results showed that soils near the smelter were heavily polluted by Cd, Cu, Pb, and As, with the mean concentrations of 4.87, 195.26, 92.65, and 35.84 mg/kg, respectively, which were significantly higher than the values of soil Cd (0.18 mg/kg), Cu (32.84 mg/kg), Pb (28.46 mg/kg), and As (13.65 mg/kg) in the reference area (p < 0.001). The concentrations of Cd and As in vegetable samples collected from smelter-affected area exceeded the maximum permissible level (MPL) for food in China by 82% and 39%, respectively. The concentrations of Cd and Pb in rice grain harvested from smelter-affected area were 9.35 and 1.35 times higher than the corresponding MPL, respectively. The concentrations of Cd, As, and Cu in fish muscle from smelter-affected area exceeded the national MPL by 72%, 41%, and 24% of analyzed samples, respectively. The concentrations of Cd (p < 0.05) and As (p < 0.01) in well water were significantly higher in the smelter-affected area than those in the reference area, respectively. The health risks to local children in the smelter-affected area were 30.25 times higher than the acceptable level of 1, and most of the risks were resulted from Cd (46%), As (27%) and Pb (20%). The intake of crops was a major source (78%) to health risks for local children.

Spatial distribution and source apportionment of heavy metals in soil from a typical county-level city of Guangdong Province, China.

The contents of ten heavy metals (Cr, Hg, As, Pb, Ni, Cd, Ti, Cu, Zn and V) in 413 topsoil samples from Puning City, Guangdong Province, China were investigated. Obvious enrichment of Hg, As, Pb, Cd and Zn were presented, and the contents of Hg and As in 5.8% and 3.4% samples respectively were higher than the guideline values recommended by the Chinese Environmental Quality Standard for Soils. Chromium and V were presented no enrichment and no pollution. According to one-way analysis of variance, the mean contents of Hg, Pb, Cu and Zn in land for construction were significantly higher than farmland and natural vegetation, but the land use had no obvious effect on other heavy metals. Furthermore, the potential sources of ten heavy metals were identified and apportioned in combination with geostatistics, correlation analysis and positive matrix factorization model. The results were following as: a) Pb, Zn and Cu mainly origin from vehicle emission and atmosphere deposition, and the hotspots approximately distributed in the areas of intensive traffic and near main roads; b) Hg and Cd were derived to industrial activities related to pharmaceutical industries, the textile and dyeing industries and e-waste recycling industries, and high-value areas were mainly concentrated in the northeast of the urban area where the industrial parks have been distributed; c) Soil parent material (Jurassic shale) was the main source of Cr, Ni, V and Ti; d) As mainly came from agricultural inputs such as pesticides or herbicides, livestock and fertilizers. Meanwhile, the contributions of four sources were 33.08%, 24.04%, 27.11% and 15.77% of the total contribution, respectively.

Assessment of exposure to heavy metals and health risks among residents near Tonglushan mine in Hubei, China.

Heavy metal contamination due to mining activity is a global major concern because of its potential health risks to local inhabitants. In the present study, we investigated the levels of Cd, Cu, Pb and As in soil, crop, well water and fish samples collected from the vicinity of the Tonglushan mine in Hubei, China, and evaluated potential health risks among local residents. Results indicate that soils near the mine were heavily contaminated with Cd (2.59 mg kg(-1)), Cu (386 mg kg(-1)), Pb (120 mg kg(-1)) and As (35.4 mg kg(-1)), and exceeded the soil quality standard values of Cd and Cu contamination. The concentrations of Cd, Cu, Pb and As in crop samples grown in mine-affected soils were significantly higher than those of the reference soils. The concentrations of Cd and As in most vegetables grown in mine-affected soils exceeded the maximum allowable level (MAL). The Cd, Pb and As concentration in rice grain collected from mine-affected soils were 2.95, 1.85 and 2.07-fold higher than the MAL, respectively. The concentrations of Cd and As in fish muscle from the mine-affected area were above national MAL in 61% and 34% of analyzed samples, respectively. All measured heavy metals except Pb were significantly greater in well water in the mine-affected area than those in the reference areas. The average estimated daily intakes of Cd and As were beyond the provisional tolerable daily intake, respectively. The intake of rice was identified as a major contributor (⩾72%) to the estimated daily intake among the residents.

[Multivariate geostatistics and GIS-based approach to study the spatial distribution and sources of heavy metals in agricultural soil in the Pearl River Delta, China].

One hundred and eighteen surface soil samples were collected from the Dongguan City, and analyzed for concentration of Cu, Zn, Ni, Cr, Pb, Cd, As, Hg, pH and OM. The spatial distribution and sources of soil heavy metals were studied using multivariate geostatistical methods and GIS technique. The results indicated concentrations of Cu, Zn, Ni, Pb, Cd and Hg were beyond the soil background content in Guangdong province, and especially concentrations of Pb, Cd and Hg were greatly beyond the content. The results of factor analysis group Cu, Zn, Ni, Cr and As in Factor 1, Pb and Hg in Factor 2 and Cd in Factor 3. The spatial maps based on geostatistical analysis show definite association of Factor 1 with the soil parent material, Factor 2 was mainly affected by industries. The spatial distribution of Factor 3 was attributed to anthropogenic influence.