Cu Distribution in Soil and Cu Accumulation in Pomelo Plants at Typical Pomelo Orchards in Pinghe County

Chemical speciation and concentrations of Cu in different layers of soil samples collected from 13 typical pomelo orchards in Pinghe, Zhangzhou, Fujian were determined based on the BCR sequential chemical extractions for an assessment on Cu pollution. The results showed that the mean Cu contents in three soil layers were 35.28, 15.60, and 13.85 mg·kg^-1. Besides being most variable, the surface layer also contained the highest amount of Cu which exceeded the provincial reference value. Of all samples, 23.1% showed Cu content higher than the standard Ⅱ for soil quality. Most of the soils contained Cu mainly in the form of residues.The proportion of residual phase in the surface layer was lower than in the deeper layers in the samples with high Cu content. Total Cu in soil affected the chemical speciation the greatest among all factors considered; and, the greater the content, the more acid extractable Cu in the sample. Soil Cu also affected Cu accumulation in the pomelo plants that grew on the lot. There was a significant correlation between the Cu content in pomel oleaves and stems and that in the orchard soil, as well as between that and the acid extractable Cu in various soil layers. Thus, the issues of high Cu in the surface soil and the severe pollution at certain pomelo orchards found in the areas should be adequately addressed.