Estrogens and xenoestrogen residues in manure-based fertilizers and their potential ecological risks

Optimal manure treatment aimed at usage as agricultural soil fertilizers is a prerequisite ecological pollution control strategy. In this work, livestock manure-based fertilizers were collected from 71 animal farms across 14 provinces in China. The contamination levels and potential ecotoxicological risks of residual steroid estrogens (SEs): estrone (E1), estriol (E3), 17α-estradiol (17α-E2), 17β-estradiol (17β-E2) and xenoestrogen (XE) bisphenol A (BPA), were investigated. The results showed that the occurrence frequencies for SEs and XE ranged from 66.67% to 100%, and the mean concentration varied considerably across the study locations. The total content of SEs and XE in Hebei province was the highest, and swine manure-based fertilizers concentrations were higher than the levels reported in other animal fertilizers. Compared with farm level manure, manure-based fertilizers are processed by composting, and the micropollutants quantities are significantly reduced (mean: 87.65 - 534.02 μg/kg). The total estradiol equivalent quantity (EEQ) that might migrate to the soil was estimated to be 1.23 μg/kg. Based on the estimated application rate of manure, 38% of the fertilizers risk quotients exceeded 0.1, indicating medium to high risks pressure on terrestrial organisms. Nonetheless, the estrogenic risk was lower in manure-based fertilizers than in manure. This study highlights the significance of proper treatment of livestock manure and designing an optimal manure fertilization strategy to mitigate the risks posed by SEs and XEs to the agroecosystems.

Antibiotics in animal manure and manure-based fertilizers: Occurrence and ecological risk assessment

The extensive use of antibiotics globally and their residues in the environment has become a serious concern. Intensive animal farming is considered to be a major contributor to the increased environmental burden of antibiotics. Although some antibiotic investigations have been advancing around the world, as an important agricultural country, the information on these pollutants in animal farms are very limited in China. Previous studies have explored few antibiotic residues in livestock farms, whereas information on some antibiotics has remained unknown. The current study analyzed residues of 32 common veterinary antibiotics in manure and manure-based fertilizers collected from Jiangsu Province, China. In most of the manure and fertilizer samples, sulfamethazine and tetracycline were present, with high concentration up to 5650 and 1920 μg·kg^-1, respectively. These detected antibiotics have weak relationships with physicochemical properties. Ciprofloxacin, enrofloxacin, sulfamethazine, and sulfachlorpyridazine, hence pose a high potential risk to crops based on the toxicological data of organisms and plants in the soil environment. However, soil invertebrate, such as earthworms, Planococcus Citri. and Folsomia fimeraria., had low ecological risks. Our results showed the presence of antibiotics in livestock and poultry farms plus the potential risks to the soil ecosystem. Therefore, the findings can provide guidelines for monitoring antibiotic residues in agroecosystems, as well as insights into the associated ecological risks of using the two products.