| 水体颗粒物的粒径和组成对多环芳烃生物降解的影响 |
| 摘要点击 1592 全文点击 1065 投稿时间：2005-04-19 修订日期：2005-06-09 |
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| 中文关键词 多环芳烃 生物降解 颗粒物 黄河 |
| 英文关键词 PAHs biodegradation particulates Yellow River |
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| 中文摘要 |
| 采用模拟实验方法,研究黄河水体颗粒物的粒径和组成对苯并[a]芘和的生物降解速率的影响及影响机制.结果表明,苯并[a]芘和在水/颗粒物混合体系的降解符合一级动力学规律,颗粒物的存在促进了二者的生物降解,并且中沙(7～25μm)的促进作用最大,细沙(<7μm)次之,粗沙(>25μm)最小.在中沙、细沙和粗沙体系中,苯并[a]芘的一级动力学常数分别为0.024 8d-1、0.021 2d-1、0.019 2d-1,的一级动力学常数分别为0.028 8d-1、0.026 1d-1、0.021 8d-1.其影响机制主要包括:①颗粒物的存在促进了体系中多环芳烃降解菌的增长,且中沙和细沙体系中微生物增长快于粗沙体系.②多环芳烃(PAHs)吸附于颗粒物表面,其解吸作用使得颗粒物附近PAHs的浓度相对较高,且由于微生物也主要生长于水/颗粒物界面,这样使得微生物和PAHs接触的机会增大.由于中沙和细沙体系中颗粒物对微生物和PAHs的吸附作用均远大于粗沙体系,因此使得中沙和细沙体系中PAHs的降解速率大于粗沙体系.另外,与中沙相比,细沙对PAHs的吸附作用更强,解吸相对困难,从而使细沙体系中PAHs的降解速率低于中沙体系. |
| 英文摘要 |
| Effect of particulate size and composition on the biodegradation of polycyclic aromatic hydrocarbons(PAHs) in nature waters was examined.Experimental study was carried out for the Yellow River.The results showed that the biodegradation of benzo[a]pyrene and chrysene in water system could be fitted with one-order kinetics and the existence of particulates promoted the biodegradation.When the particulate content was 4 g/L,the sequence of increasing trend in the PAH biodegradation rates was: water system with middle size particulates(7～25μm)>water system with small size particulates(<7μm)>water system with large size particulates(>25μm).The biodegradation rate constants for benzo[a]pyrene in water systems with middle,small and large size particulates were(0.024 8)d-1,(0.021 2)d-1,(0.019 2)d-1,respectively,and that for chrysene were(0.028 8)d-1,(0.026 1)d-1,(0.021 8)d-1,respectively.The mechanisms regarding the effects of particulate size on the biodegradation of PAHs include several aspects.First,the particulate size and composition affected the PAHs degraders level in water system as well as the distribution of PAHs degraders in water and particulate phases.The population of PAHs-degraders in water systems with middle and small size particulates was higher than that with large size particulates.Second,PAHs tended to be sorbed on the particulate phase,and the desorption of PAHs from the particulate phase would lead to a higher concentration of PAHs in the interface between water and particulate phases.Since the PAHs-degraders also tended to grow in the interface between water and particulate phases,this would result in a higher contact chances for PAHs and PAHs-degraders.Therefore,the existence of particulates stimulated the biodegradation of PAHs in water system.Third,the sorption capacity of PAHs and PAHs-degraders on the middle and small size particulates was higher than that on the large size particulates. Consequently,the biodegradation rates of PAHs in water systems with middle and small size particulates were higher than that with large size particulates.However,the desorption capacity of PAHs from middle size particulates was higher than that from small size particulates,leading to that PAHs concentration in the water/particulate interface of the former system was higher than that of the latter system.Therefore,the biodegradation rates of PAHs in water system with middle size particulates were higher than that with small size particulates. |
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