典型苯胂酸类化合物的非生物环境转化及基于铁锰氧化物的污染控制研究

p-Arsenilic acid and roxarsone are widely used as feed additives in factory farming of swine and chicken in China, and such phenylarsonic acid compounds are an important source of arsenic pollution in the surroundings of animal farms. This proposed project aims to systematically investigate the mechanism, general rule, and major influencing factors for the abiotic transformation of 4 representative phenylarsonic acid compounds (namely, p-arsanilic acid, roxarsone, nitarsone, and carbarsone), including their photodegradation in surface water and on the surface of soil grains, oxidative degradation on the surface of important metal oxides in soils, and reductive degradation on the surface of reduced minerals in anoxic sediments and soils. A range of spectroscopic techniques, including inorganic and organic mass spectrometry, X-ray photoelectron spectroscopy, infrared spectroscopy, and electron spin resonance spectroscopy, will be used to elucidate the structure-activity relationship between the molecular structures of phenylarsonic acid compounds, structures and surface chemistry of soil minerals, and the activity of photodegradation and oxidative/reductive degradation of these compounds, and to study the coupling between abiotic and biotic processes during their environmental degradation as well. The contribution of abiotic transformation to the environmental fate and ecological risk of phenylarsonic acid compounds will be systematically assessed by combining laboratory experiments, field sampling, and in situ monitoring of surface water, sediments, and soils at selected field sites in a factory farming zone located in Guangdong province. Based on the mechanistic insights obtained, novel pollution control methods will be developed using high valent iron/manganese oxides to oxidize phenylarsonic acid compounds and simultaneously adsorb the asenite/arsenate released from their degradation. The results of this proposed project are expected to enhance our fundamental understanding on the abiotic transformation of phenylarsonic acid compounds in the environment and provide scientific basis for evaluating and predicting their environmental fate and ecological risk, and to develop cost-effective treatment options for removing phenylarsonic acid compounds from animal wastes and thus preventing them from entering the environment.

阿散酸和洛克沙胂在我国集约化猪、鸡养殖业中大量使用，是养殖场周边环境重要的砷污染源。本项目拟细致研究4种苯胂酸化合物在地表环境中发生非生物转化的机制、规律以及主要影响因素，包括在表层水体和土壤颗粒表面的光降解、在土壤金属氧化物表面的氧化和在沉积物和深层土壤还原性矿物表面的还原降解。将运用多种谱学手段，解析苯胂酸化合物结构、矿物结构和表面化学性质与其光降解、氧化-还原降解的结构-效应关系，探讨苯胂酸化合物非生物降解与微生物过程的耦合，并结合室内模拟实验和对典型养殖区地表水体、沉积物和土壤样品的分析与现场监测，系统阐释非生物转化对苯胂酸化合物环境归宿和生态风险的影响。在机理研究的基础上，建立利用高价铁锰氧化物降解苯胂酸化合物并同步吸附去除无机砷的污染控制方法。研究成果将为评估和预测苯胂酸饲料添加剂的环境归宿和生态风险提供科学依据，并为防止它们随禽畜粪便施肥而进入环境提供经济有效的污染控制方法。

苯胂酸化合物作为饲料添加剂在集约化猪、鸡养殖业中大量使用，是养殖场周边环境重要的砷污染源。系统研究苯胂酸化合物在地表环境中非生物降解的机制、规律以及主要影响因素，对于认识其在表层水体和土壤中的归宿与生态风险具有理论价值。同时，建立针对苯胂酸化合物的高效污染控制方法，对于阻止它们随养殖场禽畜粪污进入地表水体和土壤、防控农田砷污染具有重要的现实意义。本项目以认识苯胂酸化合物在地表水体和土壤中非生物降解的机制、研发基于高价铁锰高效去除苯胂酸化合物的污染控制方法为目标，通过四年的研究工作基本上实现了预期目标。此外，在对典型苯胂酸类化合物的非生物降解机制与基于铁锰的污染控制方法研究基础上，扩展考察了其它类型的有机污染物的非生物降解与污染控制，并评估了苯胂酸化合物等饲料添加剂使用的环境与健康风险，丰富了研究的内容。在保证完成项目目标的前提下，探索其它相关问题体现了创新从解决实际问题入手的理念。在项目执行过程中侧重研究了典型苯胂酸化合物的光降解机制、其在土壤矿物表面的吸附与氧化降解机制，以及基于高价铁锰氧化苯胂酸化合物与吸附去除无机砷的污染控制新方法，主要成果包括：(i)解析了苯胂酸化合物在可见光照射下自敏化光降解的机理及动力学；(ii)揭示了苯胂酸化合物在典型土壤矿物以及铁酸盐纳米颗粒上的吸附机理与主要环境因素的影响；(iii)阐明了取代苯胂酸化合物在水钠锰矿上吸附与氧化降解的结构-效应关系；(iv)系统建立了基于高价铁锰的苯胂酸化合物氧化与无机砷吸附去除耦合的污染控制方法；(v)评估了苯胂酸化合物等饲料添加剂使用导致的环境与公众健康风险以及禁用苯胂酸化合物的环境与健康效益。通过本项目研究，阐明了苯胂酸化合物在地表水体和土壤中非生物降解的重要机制，建立了基于铁锰的氧化降解-吸附耦合的污染控制方法，为预测苯胂酸化合物的环境迁移与归宿行为，以及污染控制提供了理论基础和技术支持。本项目执行期间共发表标注项目资助国际SCI论文30篇、中文核心期刊论文4篇。项目执行期间，培养毕业博士人3人，毕业硕士生4人，指导出站博士后3人。