Humic Substance Effect on Photochemical Fate of PAHs

多环芳烃（PAHs）的水生光解可以受到自然界中存在的人体物质（HS）的几种方式的影响。一方面，由于有色HS作为滤光剂的竞争吸收，直接光解作用被抑制。与在纯水中的反应相比，这可能导致HS存在下的光解速率降低。另一方面，紫外线还会引起溶解有机碳（包括腐植酸、透明质酸和黄腐酸、FA）和多环芳烃的各种光化学变化，导致天然水生环境中活性氧和多环芳烃的产生可能与纯水环境中存在显著差异。在这项拟议的研究中，我们将确定选定的多环芳烃的光降解动力学在自然水域以及缓冲蒸馏水有和没有HS。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。利用微生物生物测定定向化学分馏法对光产物进行鉴定，研究多环芳烃在HA和FA存在下的光解作用机理。本研究还将探讨pH对HS与PAHs相互作用的影响。具体来说，我们将：(1)通过Mutatox试验、Microtox试验和其他技术（如呼吸测定法和微生物异养摄取葡萄糖和胸腺嘧啶）测量选定多环芳烃的急性遗传毒性和生态毒性；(2)比较了HA和FA存在和不存在时主要种类的PAHs光产物；(3)确定HS对核黄素（一种环境友好型光敏剂）对PAHs生物修复效率的影响；(4)建立个体毒性试验中毒性/抑制指数值（如Microtex试验ED50和呼吸测定技术）对HS浓度的依赖性模型；(5)评价pH对HS对多环芳烃光致毒性影响的影响。本研究的假设是：(1)腐殖质会降低地表水太阳辐照的有效性；因此，多环芳烃在天然水生环境中的光致毒性会低于其在纯水环境中的光致毒性；(2)通过对pH值的适当控制，可以成功实施多环芳烃污染水体的修复。本项目的具体目的是：1)通过微生物测定法确定HS对天然水生环境中选定多环芳烃光致生态毒性和遗传毒性的影响；(2)确定腐殖物质对候选多环芳烃持久性和降解途径的影响；(3)研究HS对敏化光解法处理多环芳烃污染水体效率和健康影响的影响；(4)确定pH对HS光致多环芳烃毒性影响的影响。长期目标是：(1)提高江苏大学在环境卫生领域的研究能力；(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。

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.