Humic Substance Effect on Photochemical Fate of PAHs

腐殖质对多环芳烃光化学归宿的影响

• 批准号: 6564503
• 负责人: HUEY-MIN HWANG
• 金额: $ 25.93万
• 依托单位: JACKSON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-02-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6564503
• 关键词: aquatic biology; bioassay; capillary electrophoresis; carbopolycyclic compound; detoxification; environmental adaptation; environmental health; environmental toxicology; gas chromatography mass spectrometry; high performance liquid chromatography; mutagen testing; nitrates; nitrites; photochemistry; photolysis; scintillation spectrometry; ultraviolet radiation; water environment; water pollution

The aquatic photolysis of polycyclic aromatic hydrocarbons (PAHs) can be influenced in several ways by the human substances (HS) present in natural waters. On one hand, direct photolysis can be inhibited because of the competitive absorption by colored HS as a light filter. This may lead to decrease in the photolysis rates in the presence of HS compared to the reactions in pure water. On the other hand, UV also induces a variety of photochemical changes in dissolved organic carbons (including humic acid, HA and fulvic acid, FA) and PAHs and lead to production of reactive oxygen species and PAHs in natural aquatic environments may differ significantly from those present in pure water. In this proposed research, we will determine the kinetics of photodegradation of selected PAHs in natural waters as well as in buffered distilled water with and without HS. HA and FA materials will be obtained from commercial source and self-extracted sources. The effect of HS on the persistence, toxicity and degradation pathways of the candidate compounds will be determined. The mechanism of PAHs photolysis in the presence of HA and FA will be studied through the identification of the photoproducts by using microbial bioassay-directed chemical fractionation approach. The influence of pH on the interaction between HS and PAHs will also be investigated in this study. Specifically, we will: (1) measure acute genotoxicity and ecotoxicity of selected PAHs with Mutatox PAHs with Mutatox Test, Microtox Test and other techniques such as respirometry and microbial heterotrophic uptake of glucose and thymidine in the presence of absence of HA and FA; (2) compare major species of the PAHs photoproducts in the presence and absence of HA and FA; (3) determine the effect of HS on bioremediation efficiency of PAHs with riboflavin (an environmentally friendly photosensitizer); (4) model the dependence of toxicity/inhibition index values (e.g., ED50 of Microtex Test and respirometric technique) in individual toxicity tests on HS concentrations; and (5) assess the effect of pH on the influence of HS on the photo-induced toxicity of PAHs. The hypotheses for this study are: (1) The humic substances can reduce availability of solar irradiation in surface waters; therefore, photo- induced toxicity of PAHs in natural aquatic environment will be lower than the counterpart in pure aqueous solutions; (2) With proper manipulation of pH, remediation of PAHs-contaminated waters can be successfully implemented. The Specific Aims of this project are: 1) To determine the influence of HS on photo-induced ecotoxicity and genotoxicity of selected PAHs in natural aquatic environments with microbial bioassays; (2) To determine the effect of humic substances on the persistence and degradation pathways of the candidate PAHs; (3) To study the influence of HS on the efficiency and health impact of using sensitized photolysis for treating PAHs-contaminated waters; (4) To determine the effect of pH on the influence of HS on photo-induced toxicity of PAHs. The long-term objectives are: (1) To enhance the research capability of JSU in th area of environmental health; and (2) To fulfill MBRS Program's mission to study the possible mechanisms by which PAHs compromise human health.

多环芳烃(PAHs)的水生光解可受到天然水体中存在的人类物质(HS)的多种影响。一方面，由于有色HS作为滤光器的竞争吸收，直接光解可以被抑制。这可能导致在HS存在下的光解速率比在纯水中的反应降低。另一方面，紫外线还可以诱导溶解有机碳(包括腐植酸、腐植酸和黄腐酸，FA)和多环芳烃的各种光化学变化，并导致自然水环境中活性氧的产生，多环芳烃的产生可能与纯水环境中的明显不同。在这项拟议的研究中，我们将测定选定的多环芳烃在天然水中以及在含有和不含有HS的缓冲蒸馏水中的光降解动力学。HA和FA材料将从商业来源和自提取来源获得。HS对候选化合物的持久性、毒性和降解途径的影响将被确定。多环芳烃在HA和FA存在下的光解机理将通过微生物生物测定指导的化学分级方法对光解产物进行鉴定。本研究还将探讨pH对HS与多环芳烃相互作用的影响。具体地说，我们将：(1)利用Mutatox测试、Microtox测试和其他技术，如呼吸测量和微生物异养摄取葡萄糖和胸苷，在没有HA和FA的情况下，测量选定的Mutatox多环芳烃的急性遗传毒性和生态毒性；(2)比较在有和没有HA和FA的情况下多环芳烃的主要光产物种类；(3)确定HS对多环芳烃与核黄素(一种环保光敏剂)生物修复效率的影响；(4)建立单独毒性测试中毒性/抑制指数值(例如Microtex测试的ED50和呼吸光敏技术)对HS浓度的依赖关系；(5)评价pH对HS对多环芳烃光毒性影响的影响。本研究的假设是：(1)腐殖质可以降低地表水中太阳辐射的有效性，因此，多环芳烃在自然水环境中的光致毒性将低于在纯水溶液中的相应物质；(2)通过适当控制pH，可以成功地修复多环芳烃污染的水体。本项目的具体目标是：1)通过微生物生物测定，确定HS对自然水环境中选定的多环芳烃的光诱导生态毒性和遗传毒性的影响；(2)确定腐殖质对候选多环芳烃的持久性和降解途径的影响；(3)研究HS对敏化光解处理多环芳烃污染水体的效率和健康影响的影响；(4)确定pH对HS对多环芳烃光诱导毒性的影响。长期目标是：(1)加强JSU在环境健康领域的研究能力；(2)完成MBRS计划的使命，研究多环芳烃危害人类健康的可能机制。