ORIGINAL RESEARCH
Contamination Characteristics, Source
Apportionment, and Health Risk
Assessment of Heavy Metals in Farmland
across Hunan Province, China
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1
Hunan University of Finance and Economics, Changsha 410205, China
2
Hunan Economic Geography Technology Development Co., Ltd, Changsha 410205, China
3
College of Resources, Hunan Agricultural University, Changsha 410128, China
4
Department of Land Resource Management, Jiangxi University of Finance and Economics, Nanchang 330013, China
5
Agriculture and Rural Bureau of Huaihua City, Huaihua 418000, China
6
Shimen County Cultivated Land Quality Monitoring and Protection Center, Changde 415300, China
Submission date: 2025-01-07
Final revision date: 2025-02-17
Acceptance date: 2025-03-17
Online publication date: 2025-06-05
Corresponding author
Ningxiang Ouyang
Hunan University of Finance and Economics, Changsha 410205, China
Bifeng Hu
Department of Land Resource Management, Jiangxi University of Finance and Economics, Nanchang 330013, China
KEYWORDS
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ABSTRACT
Heavy metal(loid)s (HMs) pollution in farmland soil and its induced health risk have attracted great
attention worldwide. Hunan Province is recognized as one of the principal rice-producing regions in
China. Its farmland is seriously threatened by HM pollution, which poses a great risk to food safety
and residents’ health. However, the spatial and vertical distribution, sources of HMs, the main factor
affecting HMs accumulation, and related pollution and health risks across Hunan Province’s farmland
largely remain unclear. To fill this gap, 62 profile soil samples were collected across the farmland of
Hunan Province with depths up to 140 cm, and their Cd, Cr, Hg, Pb, and As content were measured.
After that, the source of HMs was appointed using the positive matrix factorization model. Then,
the Shapley additive explanations methodology was adopted to quantify the relative contributions of
different natural and anthropogenic variables to HM accumulation. Finally, human health risks and
potential ecological risks were also assessed. Our results revealed a significant concentration of Cr, Hg,
Pb, and As in the farmland of Hunan Province. Only the mean value of Cd (0.42 mg kg-1) in the surface
soil surpassed the screening value for assessing the soil contamination risk regulated by the national
standard (0.3 mg kg-1, GB 15618-2018), indicating that Cd contaminates the farmland soil in Hunan
Province. The HMs were mainly enriched in the surface layer, except for As. The mean contents of Cd,
Pb, Hg, and Cr exhibited a decline as soil depth increased. The Pb and Cd in the surface soil of farmland in Hunan Province was largely sourced from industrial and traffic activities, As and Cr are mainly
derived from soil parental material, and Hg chiefly stems from atmospheric deposition. The mean
annual temperature has the largest effect on Cd, Hg, and Pb accumulation, while Fe2O3 has the largest
impact on the accumulation of As and Cr. Children and adults were treated with high carcinogenic risk
due to long-term exposure to HMs. Cr was the main contaminant for carcinogenic risks, and dermal
contact was the main route for carcinogenic risks. Our results offer empirical evidence to support the
prevention and management of HM pollution in the farmland of Hunan Province, as well as to ensure
food security.