Decabromodifenyl Ether (BDE-209) in Surface Soils from Warsaw and Surrounding Areas: Characterization of Non-Carcinogenic Risk Associated with Oral and Dermal Exposure.

Polybrominated diphenyl ethers (PBDEs) have been used for many years as flame retardants. Due to their physicochemical and toxicological properties, they are considered to be persistent organic pollutants (POPs). BDE-209 is the main component of deca-BDE, the one PBDE commercial mixture currently approved for use in the European Union. The aim of this study was to analyse BDE-209 in surface soil samples from Warsaw and surrounding areas (Poland) as an indicator of environmental pollution with PBDEs, and to characterise the associated health risk. A total of 40 samples were analysed using gas chromatography with electron capture detection (GC-µECD). Concentrations of BDE-209 in soil ranged from 0.4 ng g-1 d.w. (limit of quantification) to 158 ng g-1 d.w. Overall, 52.5% of results were above the method's limit of quantification. The highest levels were found at several locations with heavy traffic and in the vicinity of a CHP plant in the city. The lowest concentrations were observed in most of the samples collected from low industrialized or green areas (<0.4 to 1.68 ng g-1 d.w.). Exposure to BDE-209 was estimated for one of the most sensitive populations, i.e., young children. The following exposure routes were selected: oral and dermal. No risk was found to young children's health.

Quantifying Mercury Distribution and Source Contribution in Surface Soil of Qinghai-Tibetan Plateau Using Mercury Isotopes.

Long-range transport and atmospheric deposition of gaseous mercury (Hg0) result in significant accumulation of Hg in the Qinghai-Tibetan Plateau (QTP). However, there are significant knowledge gaps in understanding the spatial distribution and source contribution of Hg in the surface soil of the QTP and factors influencing Hg accumulation. In this study, we comprehensively investigated Hg concentrations and isotopic signatures in the QTP to address these knowledge gaps. Results show that the average Hg concentration in the surface soil ranks as follows: forest (53.9 ± 36.9 ng g-1) > meadow (30.7 ± 14.3 ng g-1) > steppe (24.5 ± 16.1 ng g-1) > shrub (21.0 ± 11.6 ng g-1). Hg isotopic mass mixing and structural equation models demonstrate that vegetation-mediated atmospheric Hg0 deposition dominates the Hg source in the surface soil, with an average contribution of 62 ± 12% in forests, followed by 51 ± 10% in shrub, 50 ± 13% in steppe, and 45 ± 11% in meadow. Additionally, geogenic sources contribute 28-37% of surface soil Hg accumulation, and atmospheric Hg2+ inputs contribute 10-18% among the four types of biomes. The Hg pool in 0-10 cm surface soil over the QTP is estimated as 8200 ± 3292 Mg. Global warming, permafrost degradation, and anthropogenic influences have likely perturbed Hg accumulation in the soil of QTP.

New Insight into the Natural Detoxification of Cr(VI) in Fe-Rich Surface Soil: Crucial Role of Photogenerated Silicate-Bound Fe(II).

Photoexcitation of natural semiconductor Fe(III) minerals has been proven to generate Fe(II), but the photogeneration of Fe(II) in Fe-rich surface soil as well as its role in the redox biogeochemistry of Cr(VI) remains poorly understood. In this work, we confirmed the generation of Fe(II) in soil by solar irradiation and proposed a new mechanism for the natural reductive detoxification of Cr(VI) to Cr(III) in surface soil. The kinetic results showed that solar irradiation promoted the reduction of Cr(VI) in Fe-rich soils, while a negligible Cr(VI) reduction was observed in the dark. Fe(II), mainly in the form of silicate-bound Fe(II), was generated under solar irradiation and responsible for the reduction of Cr(VI) in soils, which was evidenced by sequential extraction, transmission electron microscopy with electron energy loss spectroscopy, and electron transfer calculation. Photogenerated silicate-bound Fe(II) resulted from the massive clay-iron (hydr)oxide associations, consisting of iron (hydr)oxides (e.g., hematite and goethite) and kaolinite. These associations could generate Fe(II) under solar irradiation either via intrinsic excitation to produce photoelectrons or via the ligand-to-metal charge transfer process after the formation of clay-iron (hydr)oxide-organic matter complexes, which was proven by photoluminescence spectroscopy and X-ray photoelectron spectroscopy. These findings highlight the important role of photogenerated Fe(II) in Cr(VI) reduction in surface soil, which advances a fundamental understanding of the natural detoxification of Cr(VI) as well as the redox biogeochemistry of Cr(VI) in soil.

The Western Himalayan fir tree ring record of soil moisture in Pakistan since 1855.

Data on historical soil moisture is crucial for assessing and responding to droughts that commonly occur in climate change-affected countries. The Himalayan temperate forests in Pakistan are particularly at risk of climate change. Developing nations lack the means to gather surface soil moisture (SSM) information. Tree rings are one way to bridge this gap. Here, we employed dendrochronological methods on climate-sensitive tree rings from Abies pindrow to reconstruct the SSM in the Western Himalayan mountain region of Pakistan from 1855 to 2020. December (r = 0.41), May (r = 0.40), and June (r = 0.65) SSMs were found to be the limiting factors for A. pindrow growth. However, only the June SSM showed reconstruction possibility (coefficient of efficiency = 0.201 and reduction of error = 0.325). Over the studied period, we found 6 years (wet year) when June SSM was above the threshold of 32.04 (mean + 2 δ) and 1 year (dry year) when June SSM was below the threshold of 21.28 (mean - 2 δ). It was revealed that 1921 and 1917 were the driest and wettest SSM of all time, with means of 19.34 and 36.49, respectively. Our study shows that winter soil moisture is critical for the growing season in the context of climate change. Climate change has broad impacts on tree growth in the Western Himalayas. This study will assist various stakeholders in understanding and managing local and regional climate change.

Spatial distribution and source apportionment of surface soil's polycyclic aromatic hydrocarbons in the Yangtze River Delta.

Soil acts as a crucial reservoir of polycyclic aromatic hydrocarbons (PAHs) in the environment, and its PAH content serves as a significant indicator of regional PAH pollution. Monitoring PAH levels in soil is important for assessing the potential risks to human and environmental health. In this study, 53 surface soil samples were collected from the Yangtze River Delta. These samples were monitored for 16 priority PAHs. Pollution levels, compositional profiles, and source differences of soil PAHs were analyzed among different regions, urban and rural areas, and functional zones. The total PAH content (Σ16PAHs) in the surface soil of the Yangtze River Delta was 2326.01 ± 2901.53 ng/g. High-ring PAHs (4-6 rings) accounted for the predominant portion (85.50%) of total PAHs. The average pollution level of soil PAHs in Jiangsu Province (2651.92 ± 3242.87 ng/g) was significantly higher than that of Zhejiang Province (2001.44 ± 2621.71 ng/g) and Shanghai (1669.13 ± 1758.34 ng/g), and high-ring PAHs constituted a predominant portion in these three regions. There was no significant difference in the PAH content between urban and rural areas. In different functional areas, automobile stations exhibited the highest PAH levels among the functional zones analyzed, with traffic emissions identified as a major source of soil PAH in this area. The primary factors influencing the distribution of soil PAHs in the study area were the duration of urbanization exposure (r = 0.753, p < 0.01) and soil organic carbon content (r = 0.452, p < 0.01). This provides novel evidence for the cumulative build-up of PAHs during urbanization. The positive matrix factorization model was used to analyze the sources of PAHs in the surface soil of the Yangtze River Delta, revealing that biomass and coal combustion (60.19%) and traffic emissions and coal combustion (31.82%) were the primary sources of PAHs in the region.

Warming has a minor effect on surface soil organic carbon in alpine meadow ecosystems on the Qinghai-Tibetan Plateau.

The alpine meadow ecosystem on the Qinghai-Tibetan Plateau (QTP) is very sensitive to warming and plays a key role in regulating global carbon (C) cycling. However, how warming affects the soil organic carbon (SOC) pool and related C inputs and outputs in alpine meadow ecosystems on the QTP remains unclear. Here, we combined two field experiments and a meta-analysis on field experiments to synthesize the responses of the SOC pool and related C cycling processes to warming in alpine meadow ecosystems on the QTP. We found that the SOC content of surface soil (0-10 cm) showed a minor response to warming, but plant respiration was accelerated by warming. In addition, the warming effect on SOC was not correlated with experimental and environmental variables, such as the method, magnitude and duration of warming, initial SOC content, mean annual temperature, and mean annual precipitation. We conclude that the surface SOC content is resistant to climate warming in alpine meadow ecosystems on the QTP.

Probabilistic risk assessment of soil contamination related to agricultural and industrial activities.

Soil contamination related to industrial and agricultural activities were associated with many adverse health effects and climate change could exacerbate this effect. However, the evidence on this topic in low and middle-income countries (LMICs) is still scarce. We, therefore, aimed to investigate the heavy metals (HMs) concentrations in topsoil around Lake Urmia (which dried about 50 % of it in recent years). Accordingly, 96 surface soil samples were collected from an area of about 4000 km2 in 2019. An inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used to measure the HMs concentrations, including cadmium (Cd), arsenic (As), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), lead (Pb) and zinc (Zn). Health risk assessment of exposure to HMs was performed using Monte Carlo simulations technique. The mean concentrations of Zn, Cu, Ni, Co, Pb, Cr, As and Cd were 68.66, 35, 31.66, 15, 14.4, 11.2, 7.04, and 0.26 mg/kg, respectively, which was in the allowable range of USEPA guideline. The mean enrichment factor (EF) values for Zn, Cd, Cu, Cr, Ni, Pb, Co and As were1.3, 1.9, 1, 1.2, 1.7, 2.8, 1.8 and 2, respectively. Carcinogenic risks of exposure to HMs for inhalation, dermal and ingestion exposure pathways were at safe level. Similarly, the hazard index (HI) was at safe level (HI < 1). The sensitivity analysis indicated that the exposure duration (ED) for As, exposure frequency (EF) for Cd and Ni, concentration (Csoi) for Cr and Pb had the highest impact on ELCR values. Our finding confirmed that HMs concentrations around Lake Urmia had no health risk for inhabitants.

Faster velocity changes in the near-surface soil freeze state in croplands than in forests across northeast China from 1979 to 2020.

Climate warming has significantly changed the near-surface soil freeze state, significantly impacting terrestrial ecosystems and regional agroforestry production. As Northeast China (NEC) is highly sensitive to climate change, this study introduces the concept of velocity to analyze the spatial pattern of frozen days (FDAY), onset date of soil freeze (FON), offset date of soil freeze (FOFF), and number of soil freeze/thaw cycles in spring (FTC) in NEC from 1979 to 2020. We observed that the velocity changes of FDAY, FON, and FTC in croplands were significantly higher than those in forests (difference >1 km yr-1), with the fastest velocity changes found in the cropland of the Songnen Plain. The highest velocity of FOFF was found in the forests of the Greater Khingan Range. In most study areas (>60%), the isoline of FDAY/FON/FOFF/FTC showed a northward movement. The isoline of FDAY/FON/FOFF/FTC moved in the cold direction in each cropland region (Sanjiang, Songnen, and Liaohe River Plains) and forest regions (Greater Khingan and Lesser Khingan Ranges, and the Changbai Mountains). The results of the quantitative analysis indicate that air temperature (TA) had a more significant effect on the velocity change of FDAY and FON in cropland, whereas snowpack is the dominant factor in forests. In both forests and croplands, the main factor affecting the velocity of FOFF was snowpack, and TA mainly affected the FTC. This study is significant for formulating regional climate change countermeasures and maintaining ecological security in cold regions.

Distribution of heavy metals in surface soil near a coal power production unit: potential risk to ecology and human health.

Coal thermal power plants are the dominant factor in producing various hazardous elements in surrounding surface soil, resulting in a significant human health hazard. In the current study, the seasonal (pre- and post-monsoon) concentration of As, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Ni, Pb, and Zn in surface soil around coal power production unit was analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). The possible health risks throughout multiple exposure routes, i.e., ingestion, dermal, and inhalation were estimated for adult and children. Furthermore, geo-accumulation index (Igeo), enrichment factor (EF), pollution factor (CF), ecological risk index, and pollution load index (PLI) were applied to interpret the environmental pollution in the study area. The geospatial distribution pattern was computed to understand the trace and hazardous element distribution in the surface soil. As a result, the concentration of Fe (mg/kg) in pre-monsoon (15,620) and post-monsoon (27,180), Ni (mg/kg) in pre-monsoon (19.8), and post-monsoon (81.7) was found above the standard limits of soil prescribed by the WHO and FAO. Enrichment factor was observed between 0.95-6948 (pre-monsoon) and 0.53-116.09 (post-monsoon). The ecological risk index was found moderate to considerable for As and Cd metals during both seasons. In addition, the average PLI value was observed high for both seasons indicating the contamination of the study area with heavy metals. Moreover, Igeo values for Fe, Mg, and As were found relatively high. Conversely, health risks to the human population were found within the USEPA acceptable limits.

Responses of fungal communities along a chronosequence succession in soils of a tailing dam with reclamation by Heteropogon contortus.

Phytoremediation can obviously change the fungal communities in the soils, which will significantly impact carbon (C) and nitrogen (N) cycling in ecological system. So far, the relationship between soil fungal communities and environmental factors is still poorly understood along a long chronosequence. In this study, fungal communities in the surface and rhizosphere soils of a tailing dam with Heteropogon contortus phytoremediation were investigated to explore the evolution of fungal community in a span of 50 years. The results showed that microbial community diversity increases along with time series of Heteropogon contortus phytoremediation. The dominant Dothideomycetes (20.86%), Agaricomycetes (18.09%), and Arthoniomycetes (1.69%) in rhizosphere soils were relatively higher than those in topsoil (13.9%, 2.65%, and 0.20%) at class level. Spearman correction analysis by phylum level was conducted to detect whether microflora was related to soil Physico-chemical properties, which affecting the composition of fungal communities along with the Heteropogon contortus phytoremediation. The nitrogen cycle indicators represented good linear correlations as chronosequence goes on, the indexes in the rhizosphere soil were much higher than those in the surface soils and the highest level has occurred in the 47-year-old Heteropogon contortus phytoremediation. The relative abundance of plant pathogen, wood saprotroph, dung saprotroph, and Arbuscular Mycorrhizal showed an upward tendency in rhizosphere soils along with the Heteropogon contortus phytoremediation. The highest soil fungal communities abundance and diversity were possibly attributed to the high-quality Heteropogon contortus litter returning to the ground and artificial disturbance treatments. Such changes in soil fungal communities might demonstrate a significant step forward and provided theoretical support for the biological governance of Heteropogon contortus phytoremediation in 50 years. Our study provides an insight on microbial communities connecting with soil C, N, P and S cycles and community functions in a complex plant-fungal-soil system along a long chronosequence in mine micro-ecology.

Nitrated- and oxygenated-polycyclic aromatic hydrocarbon in urban soil from Nepal: Source assessment, air-soil exchange, and soil-air partitioning.

In contrast to more frequently investigated priority pollutants, such as polycyclic aromatic hydrocarbons (PAHs), only little is known about the fate and distribution of nitrated- and oxygenated-PAHs (NPAHs and OPAHs) in urban soils, particularly in Indian sub-continent. Moreover, experimental data on air-soil exchange and soil-air partitioning are also lacking, which is critical in assessing the partitioning, fugacity coefficient, and secondary emission of PAH-derivatives. Hence, this article provides an insight into the fate, sources, air-soil exchange, and soil-air partitioning of PAH-derivatives on a molecular basis. Prospective health risk due to their exposure has also been discussed. The result showed that PAH-derivatives had significantly polluted all four Nepalese cities. Æ©15NPAHs and Æ©2OPAHs in soil were 4 and 20 times lower than their parent-PAHs, and ranged 396-2530 ng/g (median 458 ng/g) and 91.9-199 ng/g (median 94.9 ng/g), respectively. Æ©15NPAHs was higher than a few global studies, while Æ©2OPAHs was lower than some of the less urbanized/remote areas worldwide. The 6-Nitobenzo[a]pyrene (6-NBaP) was most abundant in soil, and accounted for 10-12% of Æ©15NPAHs, while Benzanthrone (BZONE) exceeded among OPAHs, and represented 71-76% of Æ©2OPAHs, respectively. Source identification study indicated that direct emissions from domestic/residential cooking and heating and secondary formations are the essential sources of derivative chemicals in soil. Fugacity fraction ratio (fratio) indicated volatilization from the soil. The soil-air partitioning study showed sorption by soil organic matter/black carbon has little role in soil-air partitioning of PAH-derivatives in Nepal's urban soil. The toxicity equivalency quotients (TEQs) of NPAHs (314 ± 102 ng/g) was estimated slightly higher than their parent-PAHs (294 ± 121 ng/g) suggesting a relatively higher risk of soil toxicity in Nepal.

Distribution characteristics and main influencing factors of selenium in surface soil of natural selenium-rich area: a case study in Langao County, China.

In order to study the distribution of selenium in surface soil and its main influencing factor, we collected 360 surface soil samples and four groups of soil profiles with 210 corresponding parent rock samples in Langao County, Shaanxi Province (a typical high-selenium area of Daba Mountain). Samples were analyzed for trace elements by using ICP-MS, ICP-OES and HG-AFS. The results show the following. (1) selenium content in surface soils of Langao County varies greatly (0.03-16.96 mg/kg). The mean selenium content in surface soils of Langao County is 0.99 mg/kg, higher than the global (0.4 mg/kg) and China (0.29 mg/kg) soil average, and 3.4 times the mean of soil selenium in China. (2) Selenium content of bedrock in Langao County also varies greatly (0.01-56.22 mg/kg), with an average selenium content of 2.02 mg/kg, which is 40 times higher than the upper crust (0.05 mg/kg). (3) Selenium content in the strata of the Late Precambrian-Early Paleozoic and its variation is an important factor affecting the spatial variation of soil selenium content. The black rock series (carbonaceous slate and silicon-bearing carbonaceous slate) of the Upper Ediacaran-Cambrian on the north side has the highest mean selenium content (> 7.92 mg/kg), and the selenium content of the surface soil in the distribution area can reach up to 16.96 mg/kg. The Middle Cambrian, Upper Cambrian, Ordovician and Silurian (limestone and marl) in the south has the lowest mean selenium content (< 2 mg/kg), and the selenium content of surface soil in the distribution area is lower than 0.8 mg/kg mostly. (4) Soil samples at different depths in the same soil profile have similar composition of rare earth elements (REE), and bedrock and corresponding topsoil has similar composition of REE. This study indicates the selenium content in the topsoil varies greatly, even in high-selenium area. And the difference of selenium distribution is closely related to the original selenium content of the bedrock.

Estimation of surface soil moisture content using fractals.

Soil moisture content is a key factor affecting surface evaporation in the hydrologic cycle, with application in water resources management, early drought warning system, irrigation management, and estimation of crop yield. The subject of soil moisture content has long been of interest in hydrology, agriculture, forestry, and soil mechanics engineering. The cracking of surface soil due to dryness is often used to describe the drought condition of the land based on the certain relationship between soil cracking and moisture content. This study establishes the relation between fractal dimensions of soil cracking patterns and moisture content of surface soil. Sixteen soil samples were prepared and subjected to drying under different temperature levels to crack in the laboratory. Photographs of the cracks were digitized and an algorithm for calculating fractal dimensions of cracking patterns was developed. The results demonstrated that the fractal dimensions of cracking patterns are highly correlated with the surface soil moisture content; the lower the soil moisture content, the larger the fractal dimension is. Therefore, the surface soil moisture content-fractal dimension (DB-w) rating curves can be established. Once crack structures occur on surface soil, the moisture content of the surface soil can be estimated quickly and accurately by mean of remote sensing technique such as UAV together with the fractal analysis.

Spatial and temporal distributions of hexabromocyclododecanes in surface soils of Jinan, China.

Contamination by hexabromocyclododecanes (HBCDDs) in the soil environment is an ongoing concern because of their "specific exemption" on the production and use in China. In this study, spatial distribution, temporal trend, and diastereoisomer profiles of HBCDDs were examined in surface soils collected in Jinan, China. Concentrations of ΣHBCDD (sum of α-, ß-, and γ-HBCDDs) in soils ranged from 1.70 to 228 ng/g dry weight (dw), with a mean value of 26.1 ng/g dw. Soils collected from e-waste dismantling sites (mean 146 ng/g dw) contained significantly higher concentrations of ΣHBCDD than those of urban (15.5 ng/g dw) and farmland soils (3.86 ng/g dw) (p < 0.01). The temporal trend suggested that ΣHBCDD levels in the industrial area rose significantly between 2014 and 2019 (p < 0.05), with an annual increase of 12%. An increase in ΣHBCDD levels was also observed in urban and farmland soil samples during the study period, although it did not reach a significant level (p > 0.05). All surface soils were dominated by γ-HBCDD (mean 60.7% of total concentrations); however, the proportions of α-isomer increased from 28.7% in urban and rural soils to 43.4% in industrial soils. The calculated risk quotients of HBCDDs present in soils were at least 25-fold lower than the threshold limit value. The mean mass inventory of HBCDDs was approximately 2501 kg in the cultivated land of Jinan City; further studies are needed to discern the uptake of HBCDDs by crops and the fate of these chemicals in agricultural ecosystems.

A Laboratory Study on Non-Invasive Soil Water Content Estimation Using Capacitive Based Sensors.

Soil water content is an important parameter in many engineering, agricultural and environmental applications. In practice, there exists a need to measure this parameter rather frequently in both time and space. However, common measurement techniques are typically invasive, time-consuming and labour-intensive, or rely on potentially risky (although highly regulated) nuclear-based methods, making frequent measurements of soil water content impractical. Here we investigate in the laboratory the effectiveness of four new low-cost non-invasive sensors to estimate the soil water content of a range of soil types. While the results of each of the four sensors are promising, one of the sensors, herein called the "AOGAN" sensor, exhibits superior performance, as it was designed based on combining the best geometrical and electronic features of the other three sensors. The performance of the sensors is, however, influenced by the quality of the sensor-soil coupling and the soil surface roughness. Accuracy was found to be within 5% of volumetric water content, considered sufficient to enable higher spatiotemporal resolution contrast for mapping of soil water content.

Ecological and human health risk assessment of toxic metals in street dusts and surface soils in Ahvaz, Iran.

This study aimed to examine the concentrations and environmental health risk of the potentially toxic metals including Pb, Zn, Cu, Cd, Cr, and As in street dusts and surface soils of Ahvaz, the capital of Khuzestan province, located in the southwest of Iran. To this end, a total of 81 street dusts and 96 surface soils were collected from Ahvaz urban areas. Toxic metals were measured by inductively coupled plasma-mass spectrometry and evaluated using enrichment factors, potential ecological risk index and human health risk assessment. Lead in street dusts and Pb and Cu in surface soil showed the highest enrichment factor. The results revealed that there are two major sources of toxic metals in Ahvaz, including industrial activities and road traffic emissions and also resuspension of soil and dust particles. Cu, Pb, Zn, and Cr in Ahvaz soil and dust particles are strongly influenced by anthropogenic activity, mainly industrial and traffic emissions, while As and Co originate from resuspension of soil natural parent particles. The potential ecological risk index (RI) values for dust samples indicated that 58.02% of all samples showed low potential ecological risk. Moreover, 33% and 9% of samples showed moderate and considerable ecological risk, respectively. In addition, the RI values for soil samples indicated that 57% and 40% of all samples had low and moderate ecological risk, respectively, and 3% had a high ecological risk. The hazard index (HI) values of studied potentially toxic metals showed that there is no non-carcinogenic risk for children and adults. Furthermore, the HI value for children was 2-7 times upper than those for adults, which confirm that children show more potential health risks for exposition to these potential toxic metals. Cancer risks of the studied potential toxic elements for both adults and children decreased in the following order Crdust > Crsoil > Cddust > Cdsoil > Asdust > Assoil > Pbdust > Pbsoil. The carcinogenic risk values of Cd, As, and Pb for adults and children was lower than 1 × 10-6, suggesting carcinogenic risk of potentially toxic metals in the street dust and surface soil could be neglected. On the other hand, the carcinogenic risk value of Cr was greater than 1 × 10-6 for both adults and children revealing that the carcinogenic risks of Cr essentially need more consideration for environmental management control.

Trace metal pollution and ecological risk assessment in agricultural soil in Dexing Pb/Zn mining area, China.

Surface agricultural soil samples obtained from Dexing Pb/Zn mining area in Jiangxi province were analyzed for trace metals to assess their pollution status and potential ecological risk. The spatial distributions and the major trace metals pollution sources were described and identified with the combination of chemical measures and geographic information systems technology. The level of pollution in seven metals is decreasing in the following order: zinc (Zn 128.9 mg/kg) > chromium (Cr 64.1 mg/kg) > lead (Pb 58.4 mg/kg) > arsenic (As 45.3 mg/kg) > copper (Cu 41.9 mg/kg) > nickel (Ni 31.3 mg/kg) > cadmium (Cd 1.5 mg/kg). Trace metal spatial distribution maps established by geographic information system techniques displayed two high-pollution zones around mining sites in the study area. Multivariate statistical analyses were also applied, and the results demonstrated that Cd, As, Pb, Cu and Zn in the soils originated from mining activities, whereas Cr and Ni primarily originated from natural sources. The values of pollution index ranged from 4.79 to 71.59, and the values of modified pollution index ranged from 1.98 to 24.69. Moreover, the potential ecological risk values ranged from 264.0 to 3263.5, which indicated considerable ecological risk to very high ecological risk. The potential ecological risk values and other soil contamination indices showed similar patterns that the high-risk areas were around Dexing Pb/Zn mining site. The surface agricultural soil in study area is heavily to extremely polluted , with Cd that made the most dominant contribution.

Levels and human health risk assessment of heavy metals in surface soil of public parks in Southern Ghana.

This study evaluates the extent to which humans may be exposed to health risk from heavy metals in surface soils of public parks in Southern Ghana during outdoor activities. The study investigated surface soils of 56 public parks from seven metropolitan cities in Southern Ghana. Heavy metals (Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) were determined using microwave-assisted HNO3-HF acid digestion and atomic absorption spectroscopy with flame, graphite furnace, and cold vapor options. All parks studied registered the presence of heavy metals with mean concentrations following the order: Mn > Zn > Cr > Pb > Cu > Ni > Cd > Hg. Whereas the mean concentrations of Zn (221.92 mg/kg) and Cr (107.01 mg/kg) respectively exceeded the Canadian (200 mg/kg; 64 mg/kg) and the EU (100-200 mg/kg; 50-100 mg/kg) standards, the ranges of Cu (14.27-138.85 mg/kg) and Pb (6.46-628.31 mg/kg) also exceeded their EU range of 50-100 mg/kg. The results indicated that there was no immediate risk to Ni and Hg on the public parks studied; however, Pb, Cd, Zn, Cu, and Cr may pose some adverse effects as they exceed their respective guideline limits in soil. The ranges of non-carcinogenic risk for adults and children were 0.0186-0.0787 and 0.0197-0.0850 respectively while the corresponding ranges for carcinogenic risks were 3.75 × 10-7-1.28 × 10-6 and 4.17 × 10-7-1.31 × 10-6. Even though risk assessment suggested low and acceptable health risk levels to patrons, there is the need for close monitoring since Pb, Cd, Zn, Cu, and Cr have shown tendency of accumulating beyond acceptable limit.

Distribution, sources, and toxicity assessment of polycyclic aromatic hydrocarbons in surface soils of a heavy industrial city, Liuzhou, China.

As a heavy industrial city, Liuzhou has been facing a serious pollution problem. It is necessary to take steps to control and prevent environmental pollution wherever possible. Surface soil samples were collected from four communities in Liuzhou City, to determine the concentrations, distributions, sources, and toxicity potential of polycyclic aromatic hydrocarbons (PAHs) present. The mean concentrations of total PAHs in the surface soil are 756.43 ng/g for the heavy industrial area, 605.06 ng/g for the industrial area, 481.24 ng/g for the commercial-cum-residential area, and 49.93 ng/g for the rural area. Both the isomer ratio and principal component analyses for the PAHs prove that these pollutants originate mainly from coal, diesel, gasoline, and natural gas combustion. The pollution hierarchies and toxic equivalency factor of BaP prove that the city is subject to heavy pollution caused by industry, transportation, and daily human activities.