菹草(Potamogeton crispus L.)对酞酸酯污染沉积物的净化作用

Purification of sediments contaminated with phthalate acid esters by Potamogeton crispus L.

酞酸酯是一类典型的内分泌干扰物,在我国城区河湖中污染超标相对严重,且污染呈上升趋势.本文采用根袋法,模拟海河干流水体建立了室内菹草微宇宙,同时设置无菹草微宇宙为对照,研究了沉水植物菹草对沉积物中酞酸二丁酯(DBP)和酞酸二异辛酯(DEHP)的去除作用.实验连续运行27 d.结果表明:系统运行结束时,菹草体内DBP和DEHP含量分别升高了133%和68%;水中,有草组和对照组中DBP的浓度始终低于定量限(8μg/L),而DEHP的浓度则由初始的65μg/L和70μg/L逐渐降低,至第3 d后低于定量限(8μg/L);对照组和有草组非根际沉积物中DBP浓度差异不显著,结束时去除率为32.2%～36.5%,根际沉积物中DBP去除率达50.0%;对照组和非根际沉积物中DEHP浓度差异也不显著,始终在一定范围内波动,结束时去除率为10.3%～11.4%,根际沉积物中DEHP则在第27 d时迅速下降,去除率达80.9%.微生物的结果进一步表明,实验过程中根际土中微生物量明显高于对照组和非根际沉积物,实验后期根际沉积物中微生物群落结构变化较大,这与根际中这两种酞酸酯的去除数据相一致.可见,沉水植物菹草可以通过根际效应有效去除沉积物中酞酸酯类化合物.

Phthalic acid esters （PAEs） are a typical kind of endocrine disrupting compounds. The levels of PAEs in urban rivers and lakes have already exceeded the national standards and their pollution is getting more and more serious. Resorting to root bags, removal of dibutyl phthalate （DBP） and di（2-ethylhexyl） phthalate （DEHP） was studied by an indoor Potamogeton crispus L. mi- crocosm simulating the mainstream of Haihe River. An unplanted microcosm was set as a contrast. The experiments lasted for 27 d. Results indicated that the contents of DBP and DEHP in Potamogeton crispuμ L. increased by 133% and 68% at the end of the experiments. Concentrations of DBP in water were lower than the quantification limit （8 μg/L）, while the contents of DEHP in water of planted and unplanted microcosms gradually decreased from the original values 65 and 70 ixg/L to the quantification limit on the third day. Difference in the contents of DBP between non-rhizosphcre sediments and sediments in the unplanted micro- cosm was not significant, and their removal efficicncies were 32.2% -36.5% at the end of experiments, while it was 50.0% in the rhizosphere sediments. The difference in concentrations of DEHP between non-rhizosphere sediments and sediments in the un- planted microcosm was also insignificant and their removal efficiencies were 10.3%- 11.4% at the end of experiments. The con- tents of DEHP in rhizosphere sediments declined rapidly after 27th day and the removal efficiency was 80.9% at the end of experi- ments. Microbial results further revealed that the amount of microbial biomass in rhizosphere sediments were significantly higher than those in both non-rhizospherc sediments and sediments in unplanted microcosm. In the later experiment period, changes in microbial community structure in rhizosphere sediments were remarkable, which is consistent with the removal of the two PAEs in the rhizosphere. This suggests that submerged plants Potamogeton crispus L. can effectively remove the phthalate esters from sedi- ments through the rhizospherc effect.