Cycles of trace elements and isotopes in the ocean – GEOTRACES and beyondDistribution and secondary enrichment of heavy metal elements in karstic soils with high geochemical background in Guangxi, China
Introduction
The distribution and cycling dynamics of metal elements have attracted significant attention (Zhao et al., 2010) as many of them threaten environment and human health due to their toxicity, non–biodegradability and persistence in soils (Kim et al., 2015; Yajima et al., 2015). The concentration of metal elements in the overlying laterite (“red soil”) developed on karst landscapes is generally high, with most researches concluding that the enrichment in soils was related to the parent rocks (Johnson et al., 1996; Miko et al., 2000; Zhang and Lalor, 2002; Halamić et al., 2012; Yamasaki et al., 2013; Wen et al., 2020a). In karstic area, the land is usually covered by clay-rich laterite but with different thicknesses (Wang et al., 1999; Ji et al., 2004). Several hypotheses have been proposed to explain the formation of the overlying laterite in karst areas, including: (1) “Soluble–residual theory”, the accumulation of insoluble residues from the underlying carbonate rocks (Summerson, 1959; Glazovskaya and Parfenova, 1974; Isphording, 1978; Ji et al., 2004), (2) “Dissolution–metasomatism theory”, dissolution of carbonate rocks being accompanied by metasomatism with the materials carried by groundwater (Li et al., 2001), and (3) “Extraneous sedimentation theory”, the weathering of extraneous materials such as, fine–grained eolian sediments (Macleod, 1980; Inoue et al., 1993), volcanic ash (Comer, 1974; Isphording et al., 1995), and fluvial sediments (the weathering products of insoluble rocks outside karst areas; Fu et al., 2013), that are deposited during the formation of the original carbonate bedrock.
The global area of carbonate rocks exposed accounts for about 12% of the land area, and carbonate rocks exposed are mainly distributed in tropical and subtropical regions, such as the Mediterranean coast, North Africa, South Asia, southwestern China, northern Australia, western North America, and southwestern South America (Wang et al., 1999; Jin et al., 2013). China, known for stereotypical karst landforms, is covered by 2,000,000 km2 of karst, accounting for about one–fifth of the land area (Wen et al., 1994). It is mainly distributed in Guangxi, Guizhou and Yunnan provinces of southwestern China, located in the center of East Asia karst region, one of the three major karst regions in the world (Zhao et al., 2006). In addition, there are also some karst areas distributed in Sichuan, Hubei, Hunan, Jiangxi, Guangdong and other provinces in China, and most of the limestones in China are Devonian–Triassic (Zhu et al., 1984). The laterite with thickness of large variations is also widely distributed in the karst areas of China. It has been reported that the karstic soil with high geochemical background was significantly enriched with heavy metals, whose bioavailability however is generally low (Wen et al., 2020b). Meanwhile, an inheritance relationship in mineralogy and trace elements geochemistry between the overlying soils and underlying carbonate rocks has been reported (Wang et al., 1999; Ji et al., 2004).
Systematic soil sampling surveys and elemental analyses have been conducted to varying degrees of element combination size and area coverage in most countries and regions (Lalor et al., 1995; Johnson et al., 1996; Miko et al., 2000; Zhang and Lalor, 2002; Takeda et al., 2004; Halamić et al., 2012; Wang et al., 2012; Yamasaki et al., 2013; Zheng et al., 2018). Most of these surveys focused on exploring element geochemical characteristics at relatively large regional scale. Regional soil with single lithology has been rarely investigated due to the fact of complex lithology and/or significant contribution of anthropogenic contamination at large areas being explored. As a result, there leaves many unsolved problems, particularly for soils derived from carbonate rocks in karst areas.
Pollution of heavy metals in soils is increasing due to the impact of human activities, including agricultural activities (pesticide spraying, fertilization, irrigation, etc.; Ramadan and Mandil, 2009; Vodyanitskii et al., 2010; Mazur and Mazur, 2016), industrial and mining activities (Intamo et al., 2015; Fatoba et al., 2016; Ma et al., 2020), and urban residential activities (Narwal et al., 1993; Filippelli et al., 2018). In addition to human activities, both secondary enrichment of parent material and the process of soil formation influence the enrichment of metals in soil. Metals are apparently accumulated in karstic soils to varying degrees, in spite of the fact that the concentration distribution and migration characteristics of metals in soils derived from different parent rocks during the weathering process are different. Identification of the main controlling factors for this remarkable accumulation is thus very important. It's still unclear that whether the accumulation is due to parent rock inheritance, secondary enrichment in the weathering process, or the joint effect of these two factors. To address this question, we elaborately selected a typical area (covering ~1100 km2) with two adjacent sub-areas of mono-lithology (carbonate vs clastic) in Guangxi, southwestern China. Samples of un–weathered carbonate and clastic bedrocks, and surface soils in the study area were intensively collected for analysis. The objective of this study is to unravel the geochemical behavior of metal elements during the weathering process of carbonate rocks and clastic rocks, and to ascertain the main influencing factors on the accumulation of metals in karstic soils.
Section snippets
Sampling sites
The study area is located in Guigang City of Guangxi, southwestern of China (Fig. 1). Its climate is subtropical monsoon, with an annual rainfall of 1400–1600 mm (Zhou and Tang, 2013). The parent rocks are carbonate rocks and clastic rocks. Carbonate rocks are located in northwest of the study area, including Carboniferous and Devonian dolomite and limestone, and a small amount of Permian limestone. Clastic rocks are located in southeast, and are mainly Cretaceous sandstone, siltstone, Devonian
Surface soils
Statistical results of total concentration of 19 components in surface soils (0–20 cm) in the carbonate and clastic sub–areas are shown in Table 1. Surface soils in the carbonate and clastic sub–areas were weak acidic–neutral and acidic, with soil pH medians of 6.49 and 5.46. The average concentrations of SiO2, Al2O3, TFe2O3, and Mn in the soils from the two substrates were considerably higher than those of the Chinese surface soils (Hou et al., 2020), whereas the pH, and CaO, Na2O, K2O, and
Conclusions
In this study, the spatial distributions of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) were highly consistent with the geographical distribution of the carbonate and clastic substrates. In comparison with the upper continental crust, the enrichment or loss tendencies of elements in soils in the two sub–areas were consistent, with the loss of alkali metals and alkaline earth metal elements, such as Ca, Na, Mg, and K, whereas Cd, Ti, Fe, Zn, As, and Hg were 2–fold enriched. Except Cd,
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This study was financially supported by the National Key R&D Program of China (Granted No. 2017YFD0800300), the project of Geochemical study on selenium and heavy metal elements in central–eastern area of Guangxi, China (2015–2016), Study on the genesis and ecological effect of Se, Ge and Cd in soil of Guangxi, China (2017–2019), Ecological and geochemical survey and study on the heavy metals in typical soil of Guangxi, China (2018–2019), Pollution identification and ecological risk assessment
References (80)
- et al.
Determination of trace elements and evaluation of their enrichment factors in Himalayan lichens
Environ. Pollut.
(2002) Trace elements in ferromanganese concretions, gibbsite spots, and the surrounding terra rossa overlying dolomite: their mobilization, redistribution and fractionation
J. Geochem. Explor.
(2011)- et al.
Trace elements in river waters
Treatise Geochem.
(2014) - et al.
Biogeochemical factors in the formation of terra rossa in the southern crimea
Geoderma
(1974) - et al.
Geochemical Atlas of Croatia: environmental implications and geodynamical thread
J. Geochem. Explor.
(2012) - et al.
Capturing the variable reactivity of goethites in surface complexation modeling by correlating model parameters with specific surface area
Geochim. Cosmochim. Acta
(2019) - et al.
Geochemistry of red residua underlying dolomites in karst terrains of Yunnan-Guizhou Plateau: I. The formation of the Pingba profile
Chem. Geol.
(2004) - et al.
Heat transfer for falling film evaporation of black liquor up to very high Prandtl numbers. Int. J
Heat Mass Transf.
(2013) - et al.
National multi-purpose regional geochemical survey in China
J. Geochem. Explor.
(2014) - et al.
Comparing CaCl2, EDTA and DGT methods to predict Cd and Ni accumulation in rice grains from contaminated soils
Environ. Pollut.
(2020)
Cadmium distribution in soils covering Jurassic oolitic limestone with high Cd contents in the Swiss Jura
Geoderma
Goethite adsorption of Cu(II), Pb(II), Cd(II), and Zn(II) in the presence of sulfate: properties of the ternary complex
Geochim. Cosmochim. Acta
Analysis of 57 elements in Japanese soils, with special reference to soil group and agricultural use
Geoderma
Copper–gibbsite interactions: an application of 1-pK surface complexation model
Colloids Surf. A Physicochem. Eng. Asp.
Surface complexation modeling of cadmium adsorption on gibbsite
Colloids Surf. A Physicochem. Eng. Asp.
Enrichment and source identification of Cd and other heavy metals in soils with high geochemical background in the karst region, Southwestern China
Chemosphere
Evaluation of various approaches to predict cadmium bioavailability to rice grown in soils with high geochemical background in the karst region, Southwestern China
Environ. Pollut.
The PaūTa criterion and rejecting the abnormal value
J. Zhengzhou Univ. Technol.
Heavy metal contaminations in a soil–rice system: identification of spatial dependence in relation to soil properties of paddy fields
J. Hazard. Mater.
Precipitation resources characteristic analysis for Guigang city
Guangxi Water Resour. Hydropower Eng.
The Sagamu cement factory, SW Nigeria: is the dust generated a potential health hazard?
Environ. Geochem. Health
Genesis of Jamaican bauxite
Econ. Geol.
Application of chemometric methods to analyze the distribution and chemical fraction patterns of metals in sediment from a metropolitan river
Environ. Earth Sci.
Exploration for bauxite in Sri Lanka, preliminary investigations
Geol. Soc. India
Weathering Processes. (Geochemical Processes Weathering & Groundwater Recharge in Catchments)
Assessment of toxic heavy metal loading in topsoil samples within the vicinity of a limestone quarry in South Western Nigeria
Afr. J. Environ. Sci. Technol.
Heavy metal pollution and ecological geochemistry of soil impacted by activities of oil industry in the Niger Delta, Nigeria
Environ. Earth Sci.
Mapping the urban lead exposome: a detailed analysis of soil metal concentrations at the household scale using citizen science
Int. J. Environ. Res. Public Health
The influence of environmental conditions on kinetics of arsenite oxidation by manganese-oxides
Geochem. Trans.
Cause study of laterite overlying carbonate rocks
Chin. J. Rock Mech. Eng.
Modelling lead(II) sorption to ferrihydrite and soil organic matter
Environ. Chem.
Chromium(III) complexation to natural organic matter: mechanisms and modeling
Environ. Sci. Technol.
Soil Geochemical Dataset of China
Eolian dust origin of parent materials of the red and yellow soil group in the Nansei Syoto, Japan: oxygen and carbon isotopic ratio of quartz, muscovite and calcite isolated from soils, bedrocks, and piston cores
Quat. Res.
Geomorphic significance on distribution of heavy metals in soils affected by Pb-Zn mining in a limestone karst, Western Thailand
Thai J. Agric. Sci.
Mineralogical and physical properties of gulf coast limestone soils
Gulf Coast Assoc. Geol. Soc. Trans.
Depositional interpretation of limestone insoluble residues from modern and ancient carbonate rocks, caribbean and southern United States
AAPG Bull.
Element geochemistry of weathering profile of dolomitite and its implications for the average chemical composition of the upper-continental crust—Case studies from the Xinpu profile, northern Guizhou Province, China
Sci. China (Series D)
Global distribution of phanerozoic carbonates and controlling factors
Geoscience
Heavy metals in Jamaican surface soils
Environ. Geochem. Health
Cited by (78)
Water-dispersible colloids facilitate the release of potentially toxic elements from contaminated soil under simulated long-term acid rain
2024, Science of the Total EnvironmentThe desorption of n-hexadecane in calcareous soils from a karst area: Insight into endogenous Cd/Pb
2024, Environmental Technology and InnovationDifferentiating environmental scenarios to establish geochemical baseline values for heavy metals in soil: A case study of Hainan Island, China
2023, Science of the Total Environment