Geochemical Characteristics of Soil Selenium and Evaluation of Se- Rich Land Resources in the Central Area of Guiyang City, China
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Acta Geochim (2017) 36(2):240–249 DOI 10.1007/s11631-016-0136-0 ORIGINAL ARTICLE Geochemical characteristics of soil selenium and evaluation of Se- rich land resources in the central area of Guiyang City, China 1,2 2 2 2 2 Ziping Pan • Shaolin He • Chaojin Li • Wei Men • Chengzhi Yan • Fang Wang2 Received: 2 August 2016 / Revised: 28 November 2016 / Accepted: 5 December 2016 / Published online: 16 December 2016 Ó Science Press, Institute of Geochemistry, CAS and Springer-Verlag Berlin Heidelberg 2016 Abstract Based on the results of multipurpose regional certain influences upon the soil Se content as follows: dry geochemical surveys of the Guizhou Province, geochemical land [ construction land [ garden plot [ grassland = characteristics of soil Se and Se-rich land resources in the garden plot [ forest land. (3) Taking 0.4 mg kg-1 B central area of Guiyang City were studied and evaluated. x (Se) \3.0 mg kg-1 as the standard for Se-rich soil, Se-rich Major conclusions are as follows: (1) the Se content in sur- soil of the study area covered an area of 2224 km2 and 92.5% face soil of the central area of Guiyang City was 0.17– of the total area; the remaining is general soil. The study area 2.89 mg kg-1, and the average was 0.78 mg kg-1, which had no Se-excess soil. Therefore, the central area of Guiyang were respectively 2.6 and 3.9 times of the national back- City has a high proportion of Se-rich land, a large area of Se- ground value of soil and the world background value of soil. rich land resources, and a moderate selenium enrichment The Se content in deep soil was 0.11–1.48 mg kg-1, and the strength, which have been rarely seen anywhere and provide average was 0.44 mg kg-1, which were respectively 1.5 and advantageous resources for the development of Se-rich 2.2 times of the national background value of soil and the featured agriculture. world background value of soil. The soil Se content decreased with the increase in the soil depth on the vertical Keywords Central area of Guiyang Á Soils Á Selenium Á profile, and the surface soil had a higher Se content. (2) Geochemical characteristics Á Evaluation of Se-rich land Distribution of Se content was mainly affected by parent resource material, physicochemical properties of soil and other components, soil type, and land use type. Parent material played a key role, as the soil Se content was mainly origi- 1 Introduction nated from parent rock and increased with the background value of Se in parent rock, physicochemical properties of soil Selenium (Se) is a typical dispersed element with an and other components had certain influences upon the Se abundance in the earth’s crust of only 0.05–0.09 content. Se was shown to have a significant linear positive mg kg-1(Liu et al.1984). However, it is one of essential correlation with S and organic carbon but no significant trace elements for human body and animals, and it can correlation with pH value. Se content varied with different improve animals’ immunity as well as enhance the anti- types of soil as follows: skeleton soil [ yellow soil [ paddy cancer and anti-aging ability of human body (Ben et al. soil [ limestone soil [ purple soil. Land use type also had 2011; Kolachi et al. 2011; Heath et al. 2010). Additionally, it has obvious antagonistic effects on toxicity of heavy metals such as cadmium (Cd), arsenic (As), mercury (Hg), & Ziping Pan and silver (Ag) (Jarzya and Falandysz 2011). Se deficiency [email protected] may lead to white muscle disease, Keshan disease, 1 Guizhou Moutai Distillery Co. Ltd. Moutai College, Kaschin-Beck disease, and other Se-deficient diseases in Renhuai 564500, China the human body and animals (Tan 1996; Zhang et al. 2 Guizhou Academy of Geological Survey, Guiyang 550005, 1990). Excessive Se intake has toxic actions on human China body and animals and consequently causes trichomadesis 123 Acta Geochim (2017) 36(2):240–249 241 and nail discolouration to human body as well as staggers and 26°1003700–26°4905600 of northern latitude, with a total to animals (Xue et al. 2011; Ellis and Salt 2003; Thomson area of 2404 km2. 2004; Ben et al. 2011). Human body obtains Se mainly Guiyang City is located in the middle of hills in the from food (Hu et al. 2010), and soil is the storeroom of Guizhou Plateau and at the watershed between the Yangtze edible Se. This in turn determines the Se content in food, River and the Pearl River. Its terrain turns high in the vegetables and even drinking water (Tan et al. 2002; Li southwest to low in the northeast. Guiyang City is a basin, et al. 2012; Qin et al. 2013). Therefore, Se content in soil where mountains and hills cover more than 80% of the total directly affects the content of Se in food in any given area area, but dam fields cover a small area; there are also a few as well as health of human and animals. China is a Se- canyons and other landforms. deficient country, where more than ten provinces and The research area is located in the first-level geotectonic autonomous regions lack Se in varying degrees. This Se- unit- Yangtze Block of the South China plate. At its north deficient region covers about 72% of national territorial side is the fourth-level geotectonic unit-Guiyang complex area. Coal measure strata of Permian, Cambrian black shale tectonic deformation area, and at its south side is the fourth- of Cambrian, and other Se-rich rocks that are widely dis- level geotectonic unit-Guiding north–south tectonic defor- tributed in Guizhou Province establish a solid basis for Se mation area. The stratum is fully developed from the Cam- enrichment in soils. Taking different investigation meth- brian system to the Quaternary system with accumulative ods, He Yalin and Wang Ganlu have studied soil Se in the maximum thickness of above 10,000 m. The Triassic system Guizhou Province and have drawn the conclusion that the is most widely distributed and covers about 50% of the total average Se content in this region’s soil could reach 0.37 area, followed by Dyas and Cambrian strata. Most areas are and 0.39 mg kg-1, higher than the world average value and covered with neritic platform carbonate rocks, and only a few the national average value (He 1996; Wang and Zhu 2003). are covered with terrestrial river–lake red rocks. Most areas belong to the moderate Se content category, but Closely related to carbonatite parent rock, the main soil others are Se-deficient areas or Se-rich areas. The above types are yellow soil, limestone soil, paddy soil and purple studies provide basic data for further research, exploitation soil, which cover 50.97%, 29.85%, 17.42% and 1.61% of the and utilization of Se-rich land recourses. However, distri- total area. respectively. Limestone soil mainly consists of bution characteristics of regional and local soil Se and Se- argillaceous soil and arenopelitic lime soil, and yellow soil rich land resources have been rarely studied in the Guizhou mainly consists of silicoferrite yellow soil. Located in a karst Province, with the exception of some authors who have mountainous area, the study area features more mountains studied Se enrichment of soil and crops in Kaiyang County and less dam fields, heavily stony desertification, no plains, and Fenggang County (Li et al. 2004; Lian et al. 2011; Liu and a low land utilization rate. As fast urbanization and rapid et al. 2012). However, there is little research on Se geo- increase in land usage for transportation occurs, cultivated chemical distribution, Se-rich survey and evaluation in land, garden pot, forestland, water area and unused land in Guiyang City. Therefore, based on the geochemical survey Guiyang City and surrounding towns decreases sharply. results of the multipurpose region in Guizhou Province, the Land resources utilization focuses on agricultural land (in- author studies geochemical characteristics of soil Se in the cluding grassland, cultivated land and forest land), followed center area of Guiyang City and evaluates Se-rich soil by construction land and unused land, as well as water area resources, which may provide a scientific basis for the and special use area. efficient utilization of land resources and the establishment of a Se-rich agricultural production base. 2.2 Sample collection According to Multipurpose Regional Geochemical Inves- tigation Specification (1/250,000) (China Geological Sur- 2 Material and method vey 2005), surface and deep soil samples were collected using two-layer partition method. The sampling density of 2.1 Study area surface soil was 1 piece/km2, sampling depth at 0–20 cm, and a sample comprising equivalent soil was collected The research area is located in the main urban area of from at least five sampling points in the sampling lattice Guiyang City and covers seven administrative areas at the within a radius of 50 m, with the sample weight of district (or county) level in the central area such as Yunyan C1000 g. The sampling density of deep soil was 1 piece/ District, Nanming District and Xiaohe District, as well as 4km2, the sampling depth was 150–200 cm, soil samples suburbs such as Huaxi District, Baiyun District, Wudang were collected by using twist drill, and the sample weight District and Jinyang New District. The geographical was C1000 g. Considering representativeness, uniformity coordinates are 106°3000200–106°5902900 of east longitude and controllability, sampling points were allocated in 123 242 Acta Geochim (2017) 36(2):240–249 paddy fields, dry land, garden plot and forestland in order furnace atomic absorption spectrometry (GFAAS) was used to avoid man-made pollution and recent cumulose soil.