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... The mobility and bioavailability of TEs in the five fractions in sequential extraction order show a gradually decreasing trend; [22] therefore, the mobility factor D i values of the waterextractable, acid-soluble, reducible, oxidizable, and residual fractions were set as 1, 0.8, 0.6, 0.4, and 0.2. The background concentration C b values of B, V, Cr, As, Se, Mo, Sb, and W were chosen as 46.9, 66, 40, 9, 0.51, 1.11, 0.68, and 3.34 mg kg 21 , based on suggestions from the literature [23]. ...
... To date, although regional eco-geochemical surveys have been well carried out in most provinces in China, the Leizhou Peninsula is still in a gap in terms of land quality geochemical surveys and regional ecogeochemical surveys (Chai et al., 2019). Since the reform and opening-up policy, the Leizhou Peninsula has achieved rapid social and economic development, yet it has also paid a heavy price in terms of resources and the environment, e.g., the decline in the quantity and quality of natural resources has seriously affected food security production and the cleanliness of the human environment, and restricted the sustainable and rapid socio-economic development of the region (Li et al., 2014;Dou and Li, 2015;Cai et al., 2019;Wang et al., 2020a). To improve the ecological environment and provide a scientific basis for economic and social development and planning, we carried out a geochemical survey of land quality over the Leizhou Peninsula. ...
The Leizhou Peninsula is an important base for tropical and subtropical cash crops in China, but still lacks systematic research on regional eco-geochemical characteristics. Here the elemental results show that risk-free soils accounted for 9168 km² and were mainly concentrated in the northern Leizhou Peninsula, while risk-controllable soils occupied 3318 km² and were mostly distributed in the southern part. The contributor of the heavy metals in soils was mainly natural rocks, while the road traffic dust and coal combustion were also responsible for the origin of anomalous elements Cd, Cr, and Ni (0.004–1.8, 0.76–590, and 0.14–372 mg/kg, respectively). 90.15 % of the Leizhou Peninsula plants were not obviously contaminated, yet the comparison between the data collected in 1997 and 2018 allows us to speculate that Ni in the studied soils will reach the risk screening value in 7 years, followed by Cr and Cu in 39 and 92 years, respectively.
... According to a report of the National General Survey of Soil Contamination in China (2014), the total excess rate of heavy metals in soil is 16.1%, of which the proportions of slightly, lightly, moderately, and severely polluted sites were 11.2, 2.3, 1.5 and 1.1%, respectively, and the excess rates of Cd, Hg, As, Pb, Cu, Cr, Zn, and Ni were 7.0, 1.6, 2.7, 1.5, 2.1, 1.1, 0.9 and 4.8%, respectively. Soil heavy metal pollution as a result of natural background and anthropogenic factors significantly affects environmental quality [1][2][3][4][5][6][7][8][9][10][11]. Heavy metal pollution can not only cause changes in soil composition, structure and function, but also inhibit crop root growth and photosynthesis, resulting in crop yield reduction or even no harvest. ...
... However, with the continuous development of regional large-scale land quality geochemical surveys in China, a set of efficient and effective regional assessment methods with high survey accuracy and a large amount of elemental data to evaluate heavy metal ecological risk has not been developed [17,43]. Unlike previous studies, this study is based on the 1:50,000 land quality geochemical survey, and aims to achieve the following objectives: (1) extract the key influencing factors via a principal component analysis (PCA) superimposed with the background for soil geochemical zoning; (2) evaluate the environmental quality status and potential ecological risk of eight heavy metals in soil geochemical zoning; and (3) the relationship between different evaluation methods is discussed. This study selected Yishui County, a typical agricultural county in northern China, as a case study, and will provide pertinent information for zoning risk assessments and controlling heavy metal pollution in agricultural lands. ...
Various human production activities have caused tremendous damage to the soil ecological environment of cultivated land. Regional ecological risk assessments and the safe use of cultivated land have received widespread attention. The ecological risk assessment of heavy metals based on soil geochemical zoning has not been reported in the past. Using 14,389 topsoil samples, considering comprehensive geological background information, Yishui County in northern China was divided into three soil geochemical areas and 14 soil geochemical sub-regions by means of principal component factor superposition. The results of environmental quality and risk assessments of eight heavy metals based on soil geochemical zoning show that the single pollution index was greater than 1.0 and the Nemerow pollution index was greater than 0.7 for Ni in a sub-region, indicating that Ni pollution had reached the early warning limit, which demonstrates that Ni has a certain enrichment trend. Meanwhile, the geoaccumulation index of Ni and Cr was greater than zero in some sub-regions, indicating a slight pollution level. In addition, the potential ecological risk factor of the measured heavy metals was greater than 40 in 9 sub-regions, indicating a moderate ecological hazard, and the risk index was greater than 150 in a sub-region, revealing moderate ecological intensity, in which Hg and Cd were leading contributors to potential ecological hazards with a contribution rate between 58% and 76%. This method is suitable for the evaluation of soil environmental quality and safety for medium and large scales, and can provide a scientific basis for further zoning and grading prevention and control of soil pollution in cultivated land.
... Reduced rainfall and lower flow rates recorded in the Nyong River have been reported worldwide. In China, it is much more pollution of rivers and watertable [19]. In the Polar Regions is melting glacial ice [15]. ...
The transfers of potential toxic elements (PTEs) from root soil to rice grains and its driving factors are of major worldwide concern. And it is still not clear whether the parent material has influence on the transfers of PTEs in soil. Thus, the aim of this study is to investigate the transfers of PTEs in soil‐rice system from different parent materials area, identify its driving factors and evaluate human health risk. 157 sets of root soil and rice grains samples collected from the areas with quaternary sediments, acidic magmatic rocks and terrigenous clastic rocks in the Pearl River Delta, China. Pearson correlation analysis, discriminant analysis, redundancy analysis, path analysis and human health risk model were utilized for data processing and analysis. The results reveal that parent materials play a primary role affecting the transfers of PTEs in soil‐rice system, and its influence on transfers of PTEs is achieved by governing physicochemical properties of soil. And physicochemical parameters like MgO, SiO 2 , Al 2 O 3 , TFe 2 O 3 , and organic matter (OM) exerted significant influence on transfers of PTEs. The influences of some physicochemical parameters on the transfers of PTEs are most significantly in the area of quaternary sediments. The values of the total non‐carcinogenic and the total carcinogenic risks for children and adults caused by rice consumption are much higher than the corresponding risk limits, and the main contributing elements are Pb, As, and As, Cd, respectively. The human health risks caused by rice consumption are greatest in the area with quaternary sediments.
Although anthropogenic contamination has been regarded as the most important source of potentially toxic elements (PTEs) in soils of large river delta plains, the extent to which human activities affect PTEs in soils is worth exploring. This study used high density geochemical data to distinguish source patterns of PTEs in soils of the Pearl River Delta Economic Zone, a large industrialized and urbanized area in China. Enrichment factor, discriminant analysis, principal components analysis, cumulative distribution function, and positive matrix factorization were used to identify sources of PTEs in soils. The results indicated that parent material was the most significant factor affecting geochemical characteristics of PTEs in soils. Median concentrations of Cd, Cr, Cu, Hg, Pb, and Zn were 0.400, 88.5, 40.5, 0.143, 43.0, and 116.0 mg/kg for stream sediments, 0.333, 75.7, 39.0, 0.121, 42.6, and 98.5 mg/kg for deep soils, and 0.365, 74.0, 45.1, 0.143, 44.6, and 119.5 mg/kg for surface soils, respectively, all of which exceed relevant reference standards. Compared with stream sediments and deep soils, surface soils exhibit substantial concentrations of PTEs. Chemical weathering and erosion of parent materials distributed in the Pearl River Delta were the main sources of PTEs in soils. Diffuse contamination and many small local contamination sources distributed throughout the study area were the most significant anthropogenic sources of PTEs in surface soils. Intensive human activities failed to change the soil geochemical characteristics derived from the parent material at the regional scale. However, it could induce non-point source pollution and local severe PTEs pollution in surface soils.
Land use change is an essential driver of global environmental change, yet the extent and nature of global land use practices are still poorly understood. A study was conducted under four different land uses (Pasture, fertilized cropland, vegetable garden treated with municipal waste in Zaria and Afaka forest). Forty samples from surface soils (0 - 20cm) and profile pits were collected to determine soil physical and chemical properties. Soil properties determined include particle size distribution, bulk density, pH, exchangeable bases, cation exchange capacity (CEC), organic carbon (OC), total nitrogen (TN), and available phosphorus (AP). Results of the analysis showed that surface soils are predominantly sandy loam in all the land uses. At the same time, the texture of profile soils ranged from sandy loam, sandy clay loam, and clay loam depending on the land use and horizon. The pH at both the surface soils and down the horizons is slightly acidic (6.03-6.80) in all the four land uses. Exchangeable calcium ranged from low down the pro-file, to moderate at the surface in all land uses except Sabo where it was found high. Potassium and sodium were both found low at 0-20 cm and various depths in the pedons. CEC under Sabo land use recorded the highest value (13.90 cmol(+)/kg) on the surface soil as opposed to other land uses which recorded moderate values. OC was found low in all the soils with the lowest value of 0.50 g/kg found on the surface soil in IAR and the highest value of 1.43 g/kg found in Afaka soil. TN mean ranged from 0.47 g/kg for Afaka soil to 3.03 g/kg for Sabo soil. AP was observed to decrease with depth, while high values were obtained on surface soils. The results showed that different land uses affect the physical and chemical composition of soils.
A determination of soil heavy metal (Cu, Mn and Ni) concentrations in Perlis state, Malaysia was performed to define the level of soil pollution. Six soil samples were collected at depth of 0 – 15 cm in industrial, residential and school areas around Perlis. The highest concentration of Mn (57.80 mg/kg) and Ni (2.83 mg/kg) were detected at limestone quarry in Bukit Air, Cu (17.43 mg/kg) in Kampung Wang Ulu. The concentration of Cu, Mn and Ni were well below their soil geochemical background values. The single pollution indices assessment revealed that the soil contamination due to heavy metals in Perlis is insignificant. On the basis of the heavy metal content, the potential health risk assessment for children and adults was calculated for a lifetime of exposure through ingestion, inhalation and dermal contact based on the USEPA model. The exposure assessment found that the exposure pathways of heavy metals to both children and adults are through ingestion. Both Hazard Quotient (HQ) and Hazard Index (HI) values are lower than 1, indicating no health risk. From the result, the HI values indicated that the soil heavy metal contamination could pose more impacts on children as compared to adults.
