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摘要
Estrogenic compounds in livestock manure are also present in soils because manure is land applied on account of its Value as an important nutrient source in agricultural production. This is the first study to compare the sorption of 17 beta-estradiol. estrone, estriol and equol in a wide range of soils. Specifically, for each of these four estrogens, the soil sorption coefficient (K(d)) and the sorption coefficient per unit organic carbon (K(oc)) were determined in 121 surface soils (0-15 cm) obtained from upper-slopes, mid-slopes, and lower-slopes in agricultural fields across seven ecoregions in the Province of Alberta, Canada. Soil organic carbon content (SOC). texture, pH, carbonate content, electrical conductivity and cation exchange capacity were also determined on the air-dried and sieved (2 mm) soil. Both K(d) and K(oc) values significantly increased in the order of K(d)-estriol (23 L kg(-1) soil and 1059 L kg(-1), respectively) = K(d)-17 beta-estradiol (23 L kg(-1) soil and 1082 L kg(-1), respectively) <K(d)-estrone (33 L kg(-1) soil and 1557 L kg(-1), respectively) <K(d)-equol (42 L kg(-1) soil and 2080 L kg(-1), respectively). For each estrogen, SOC was the strongest significant factor explaining variations in K(d) values among soils and particularly small K(d) values were observed when SOC was below a threshold value of 10 g C kg(-1). Regardless of the estrogen, the Mixed Grassland ecoregion characterized by Brown Chemozern soils, as well as upper-slopes in general, demonstrated lesser K(d) values because of reduced SOC. However, regardless of the estrogen, the soils with reduced SOC displayed greater K c values. Equations to predict 17 beta-estradiol, estriol, estrone or equol K(d) or K(oc), values at the regional level were established using either soil properties (Partial Least Squares (PLS) regression) or one single estrogen (ordinary least squares regression). Regardless of the estrogen or the regression used, the strength of the prediction model, as determined by the coefficient of determination (r(2)) and other factors, was always better for K(d) than K(oc) values. Regardless of the regression used, the r(2) of the prediction models exceeded 0.70 for K(d)-17 beta-estradiol and K(d)-estriol, but r(2) was below 0.52 for K(d)-equol. For both K(d) and K(oc) values. the prediction using soil properties (ranging from a r(2) of 0.51 to 0.87 for K(d) and from a r(2) of 0.32 to 0.44 for K(oc)) always provided better prediction models than using a single estrogen (ranging from a r(2) of 0.38 to 0.71 for K(d) and from a r(2) of 0.18 to 0.40 for K(oc)). We conclude that data on basic soil properties are good tools for estimating K(d) values of 17 beta-estracliol, estrone and estriol in western Canadian soils. Additional studies are required to seek better prediction models at the regional scale for estimating K(d)-equol and for estimating K(oc) values of estrogens, particularly because such information could be important for agri-environmental policy analyses in Canada and elsewhere.
- 出版日期2010-2-15
