The Grain for Green Project May Enrich the Mercury Concentration in a Small Karst Catchment, Southwest China

Rui Qu and Guilin Han
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Rui Qu: Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, China
Guilin Han: Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, China

Land, 2020, vol. 9, issue 10, 1-13

Abstract: The Chinese project, better known as the Grain for Green Project (GGP), has changed the land-use type in the karst area of Puding county, Guizhou province, southwest China, and this study is aimed at evaluating the Hg distribution and determining factors in soils after the land-use change. A total of ten soil profiles were selected in the typical karst region, and the land-use types were divided into native vegetation land (NVL), farmland (FL), and abandoned farmland (AFL). Total Hg concentration under different land-use types increased in the order: NVL (average 63.26 μg∙kg −1 ) < FL (average 71.48 μg∙kg −1 ) < AFL (average 98.22 μg∙kg −1 ). After agricultural abandonment for four to five years with a cover of native vegetation in the AFL, a higher concentration of Hg compared to the other two land-use types indicate that the Hg accumulation in soil results from vegetation restoration of AFL due to land-use change. Soil organic carbon (SOC) and macro-aggregates were highly correlated to Hg concentration in this study. Macro-aggregates can provide a stable condition for Hg due to the thin regolith and high porosity in the karst region. A high proportion of macro-aggregates can reduce the mobility of Hg in the karst area. Intense tillage can significantly reduce the formation of macro-aggregates in FL, but the macro-aggregates in AFL were recovered as well as those in NVL, resulting in the accumulation of Hg.

Keywords: mercury; Grain for Green Project (GGP); land-use change; soil organic carbon (SOC) and soil aggregate; karst soils; Southwest China (search for similar items in EconPapers)
JEL-codes: Q15 Q2 Q24 Q28 Q5 R14 R52 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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