Abstract
Eighteen forests of Camellia oleifera in Hainan province, China were selected to measure the contents of selenium (Se), zinc (Zn), mercury (Hg), cadmium (Cd), chromium (Cr), lead (Pd) and arsenic (As) in soils, roots, leaves, and kernels, and analyze the correlation between the soil content and the corresponding content in the plant. It was found that the content of Se in soils ranged between 0.489 and 2.110 mg/kg, and was higher than 1.0 mg/kg in 10 out of 18 forests. The average content of six heavy metals was low and fulfilled the requirements of soil environment for green-food production, except that the contents of Cr, Pb, and Cd exceeded standards in few regions. The content of Se in Camellia oleifera was relatively low. Only five regions showed detectable levels of Se in kernels, with the highest in Fuwen Town of Dingan county of 0.085 mg/kg. The contents of Zn, Cr, Pb, Cd, As, and Hg in roots of Camellia oleifera were higher than in the leaves and kernels. The contents of Zn, Cr, and Pb were higher than that of Cd, As, and Hg. The As content in soil was in significant correlation with that in the roots of Camellia oleifera. The Pd content in the soil was positively correlated with that of the roots of Camellia oleifera. The Cr, Pd and Cd contents in roots were in positive correlation with that in the leaves significantly. However, the Hg content of the roots was positively correlated with that of the kernels. Furthermore, the Se content in roots of Camellia oleifera was negatively associated with that of the other six heavy metals, having a significantly negative correlation between Se and As.
Highlights
Soil is an integral part of human ecological environment, and the foundation of agriculture and forestry production
There was significant positive correlation between roots and kernels with regard to Hg content; whereas, significant negative correlation was found between roots and kernels in terms of Cd content, implying that Cr and Cd are translocated from roots to leaves, and Hg from roots to kernels
The enrichment coefficient was relatively higher for Zn, Cr and Pb by the roots of Camellia oleifera, which was consistent with the study based on tropical trees such as Casuarina equisetifolia [24]
Summary
Soil is an integral part of human ecological environment, and the foundation of agriculture and forestry production. Heavy metal pollution adversely affects the growth and development of plants and the quality of agricultural products [1]. Studies focused on selenium (Se) and the other heavy metals in the soils cultivating rubber and pepper found abundant Se in soil in the Hainan province [6,7,8]. Camellia oleifera is an important and major source of edible oil in South China [9, 10]. It has a long history of planting and utilization in Hainan province. Known as ‘pomelo on the hill’, Camellia oil from Hainan province is of high quality due to excellent production environment. Studies have been published on Camellia oleifera germplasm resources [11], varieties
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