Occurrence of nonylphenol and nonylphenol monoethoxylate in soil and vegetables from vegetable farms in the Pearl River Delta, South China.

ABSTRACT

Low molecular-mass nonylphenol ethoxylates (NPEOs) and 4-nonylphenol (NP) are biodegradation products of higher molecular mass NPEOs used as surface active agents, and they are endocrine-disrupting contaminants. In this study, surface soil (0-20 cm) samples and different vegetable samples were collected from 27 representative vegetable farms located in Shenzhen, Dongguan, and Huizhou within the Pearl River Delta region, South China, and NP and nonylphenol monoethoxylate (NP(1)EO) were analyzed using high-performance liquid chromatography with ultraviolet detection. The results show that NP and NP(1)EO were detected in soil and vegetable samples. The concentrations of NP and NP(1)EO in soil samples ranged from nondetectable (ND) to 7.22 µg kg(-1) dry weight (dw) and from ND to 8.24 µg kg(-1) dw, respectively. The average concentrations of both NP and NP(1)EO in soil samples decreased in the following order Dongguan > Huizhou > Shenzhen. The levels of NP and NP(1)EO in vegetable samples varied from 1.11 to 4.73 µg kg(-1) dw and from 1.32 to 5.33 µg kg(-1) dw, respectively. The greatest levels of both NP and NP(1)EO were observed in water spinach, and the lowest levels of NP and NP(1)EO were recorded in cowpea. The bioconcentration factors (the ratio of contaminant concentration in plant tissue to soil concentration) of NP and NP(1)EO were <1.0 (mean 0.535 and 0.550, respectively). The occurrences of NP and NP(1)EO in this study are compared with other studies, and their potential sources are discussed.