Effect of biochar on fate and transport of manure-borne estrogens in sandy soil.

The feasibility of using two types of biochars to reduce steroid hormone pollution from poultry and swine manure application on agricultural land was evaluated. The sorption affinity and desorption resistance of softwood and hardwood biochars were also determined for two estrogen hormones, 17β-estradiol (E2) and its primary metabolite estrone (E1). The softwood and hardwood biochars demonstrated high retention capacity for both estrogens. The effective distribution coefficient (K) of soil-softwood-derived biochar (SBS) was significantly higher than soil-hardwood-derived biochar (SBH), indicating the stronger sorption affinity of SBS for estrogens. To validate the laboratory results, a field lysimeter experiment was conducted to study the fate and transport of E2 and E1 in soil and leachate in the presence of 1% softwood-biochar (BS) in topsoil and to compare it with soil without any amendments. The spatio-temporal distribution of both estrogens was monitored at four depths over a 46-day period. The lysimeters, in which the surface layer of soil was amended with biochar, retained significantly higher concentrations of both estrogen hormones. Although they leached through the soil and were detected in leachates, collected at 1.0m depth, the concentrations were significantly lower in the leachate collected from biochar-amended lysimeters. The result confirmed the efficacy of biochar amendment as a remediation technique to alleviate the manure-borne hormonal pollution of groundwater.