College of Agriculture and Biotechnology, China Agricultural University, Beijing 100093, People's Republic of China.
J Agric Food Chem. 2012 Apr 25;60(16):3999-4004. doi: 10.1021/jf300479z. Epub 2012 Apr 10.
Levonorgestrel, a synthetic progesterone used as an oral contraceptive or emergency contraceptive pill, has been shown to be an endocrine-disrupting chemical. To assess the environmental risk of levonorgestrel, batch experiments and laboratory microcosm studies were conducted to investigate the adsorption and degradation of levonorgestrel in five contrasting soils of China. Freundlich and Langmuir models were applied to sorption data to examine the affinity of levonorgestrel for soils with varying physical and chemical properties. The K(f) of levonorgestrel in the tested soils ranged from 10.79 to 60.92 mg(1-n) L(n) kg(-1) with N between 0.69 and 1.23, and the Q(m) ranged from 18.18 to 196.08 mg/kg. The multiple regression analysis was conducted between K(f) and soil properties. Results indicate that total organic carbon plays a dominant role in the adsorption process. Gibbs free energy values less than 40 kJ/mol demonstrate that levonorgestrel sorption on soils could be considered as a physical adsorption. The degradation of levonorgestrel in five soils was fitted by the first-order reaction kinetics model. The half-lives of levonorgestrel were between 4.32 and 11.55 days. The initial concentration and sterilization experiments illustrated that the degradation rate of levonorgestrel in soil was concentration-dependent and microbially mediated. The low mobility potential of levonorgestrel in soils was predicted by the groundwater ubiquity score (GUS) and retardation factor (R(f)).
左炔诺孕酮是一种合成的孕激素，被用作口服避孕药或紧急避孕药，已被证明是一种内分泌干扰化学物质。为了评估左炔诺孕酮的环境风险，进行了批实验和实验室微宇宙研究，以研究在中国五种不同土壤中左炔诺孕酮的吸附和降解。应用 Freundlich 和 Langmuir 模型来研究吸附数据，以考察左炔诺孕酮对具有不同物理和化学性质的土壤的亲和力。在测试的土壤中，左炔诺孕酮的 K(f)值范围为 10.79 至 60.92 mg(1-n) L(n) kg(-1)，N 值范围为 0.69 至 1.23，Q(m)值范围为 18.18 至 196.08 mg/kg。对 K(f)和土壤性质之间进行了多元回归分析。结果表明，总有机碳在吸附过程中起主要作用。吉布斯自由能值小于 40 kJ/mol 表明，左炔诺孕酮在土壤上的吸附可以被认为是一种物理吸附。五种土壤中左炔诺孕酮的降解符合一级反应动力学模型。左炔诺孕酮的半衰期在 4.32 至 11.55 天之间。初始浓度和灭菌实验表明，土壤中左炔诺孕酮的降解速率与浓度有关，并受微生物介导。地下水普遍得分（GUS）和阻滞因子（R(f)）预测了左炔诺孕酮在土壤中的低迁移潜力。
