畜禽养殖排放的雌激素对周边水体环境的影响

环境雌激素是一大类化学物质，它们能够干扰生物体内激素的合成、分泌、转运、活性等，或与生物体内激素结构相似而发挥激素作用，对生物体的生长、繁殖及行为产生不利影响。环境雌激素包括天然雌激素及人工合成类雌激素。随着国内畜禽养殖的规模与数量的不断扩大，养殖场成为了一个很大的环境雌激素的产生源，其环境风险应得到相应的重视。目前对畜禽养殖过程中环境雌激素的产生量以及雌激素进入环境后的迁移转化行为已有很多的研究，包括野外的调查与实验室内机理研究。畜禽养殖过程产生的大量雌激素进入环境后能够被土壤吸附及微生物降解。室内的静态平衡吸附实验、土柱迁移试验及降解研究均表明雌激素进入环境后绝大部分迅速被吸附到土壤颗粒或悬浮胶体、沉积物颗粒上，同时发生转化与生物降解，由此推断其对周边环境中的雌激素贡献很小。然而，野外调查结果却表明实际情况下雌激素的迁移性高于理论期望值。因此，畜禽养殖对周边环境中雌激素的贡献量的大小尚未明确。本论文综述了畜禽养殖过程中环境雌激素的排放情况，结合国内外的调查研究，阐述了畜禽养殖产生的环境雌激素在土壤及水体中的迁移与降解行为，探讨了影响准确评估畜禽养殖排泄物对周边水体中雌激素贡献大小的因子，并提出了今后应开展原位吸附与迁移的实验，重点考虑天然有机质及抗生素等共存物质对雌激素环境行为的影响，建立综合模型来估算不同时期养殖场对周围水环境雌激素的贡献量的建议。

Effects of estrogens on water environment by livestock excretion

Environmental estrogens are a class of hormones which can interfere with the biological synthesis, secretion, transport, activity, or play the role of hormones because of the similar structure with biological hormone. These chemical substances may adversely affect the growth, reproduction and behavior of the organisms. The contamination of estrogens will disrupt the endocrine systems and induce sexual abnormalities in wildlife, and may lead to the disappearance of the species. They can be divided into natural estrogens and synthesized estrogens. Farm livestock excreta may be a major source of estrogen and its risk should be concerned. Many studies have been carried out on their environmental behaviors, including experiments in the lab and the field investigations. The large amount of estrogens generated from livestock could be absorbed to the soil particles, suspended colloids or sediment particles rapidly and then degraded by biotic pathways when they are released into the environment, which has been proved by the static equilibrium adsorption experiments, soil column experiments and biodegradation experiments. Thus it has been suggested that the contribution of livestock farming to the estrogens in the surrounding environment is very small. However, the field investigation results show that the migration of estrogen was higher than the theoretical expectations. So a link between the estrogens from farms excrement with the endocrine disruption in surrounding water environment is still not clear. Research progresses on mobility and degradation of estrogens and results of field studies, as well as the amount of estrogens produced by livestock, are introduced in detail in this paper. Subsequently contribution of estrogens by livestock to water environment is discussed. Estimation of the impact of livestock farming on the surrounding water environment in different periods by establishing a comprehensive model after in situ experiments and study on the influence of coexisting substances such as natural organic matter and antibiotics is proposed.