普通小球藻对邻苯二甲酸二丁酯的富集与降解研究

Accumulation and Biodegradation of Dibutyl Phthalate in Chlorella vulgaris

本实验选取一种典型的富营养化优势藻种普通小球藻(绿藻),研究该藻对典型内分泌干扰物邻苯二甲酸二丁酯(DBP)的富集和降解过程。实验在250mL锥形瓶中进行,采用气相色谱分析样品中DBP浓度变化。结果表明,普通小球藻对DBP有明显的富集,但生物降解作用并不显著,且降解符合一级反应动力学。(1)T=25℃,DBP初始浓度分别为0.198、1.82和4.85mg·L-1时,藻相中DBP浓度分别在12、1和1h达到最大,最大值分别为1.37、85.9和238mg·g-1DW;生物浓缩系数(BCFs)分别在12、1和1h达到最大,最大值分别为8.01×103、4.83×104和5.36×104;生物降解速率常数(kA)分别为0.00、0.80×10-3和0.30×10-3h-1。这可能是由于DBP初始浓度过低导致藻细胞中DBP浓度很小,从而藻对DBP的降解作用不明显;DBP初始浓度较高,对普通小球藻产生了毒性效应,从而抑制了藻的生长和藻体中相关酶的活性,导致降解程度较低。(2)DBP初始浓度约为2.00mg·L-1,实验温度分别为13℃和25℃时,藻相中DBP浓度和BCFs均在1h达到最大,最大值分别为24.0mg·g-1DW及1.23×104和85.9mg·g-1DW及4.83×104;kA分别为0.60×10-3和0.80×10-3h-1。这说明,在普通小球藻适宜生长温度范围内,温度升高有利于藻对DBP的生物降解。

Bioconcentration and biodegradation of dibutyl phthalate（DBP）in Chlorella vulgais were investigated. DBP is a kind of typical endocrine-disrupting（ED ）substances. Chlorella vulgaris is a sort of dominant algae in eutrophic waters. Experiments were performed in 250 mL flasks, DBP was analyzed with GC-FID. Experimental results showed that Chlorella vulgaris was able to accumulate DBP significantly, but biodegradation of DBP by the alga was lower. The decrease of DBP in algal solution was described satisfactorily by a first-order kinetic equation. （ 1 ）At 25 ℃, with the increase of initial DBP concentrations（0.198, 1.82, 4.85 mg· L^-1）, DBP accumulation in alga reached the maxima of 1.37 mg·g^-1DW at 12 h, 85.9 mg·g^-1DW at 1 h, 238 mg·g^-1DW at 1 h, respectively. Bioconcentration factors（ BCFs ）reached the maxima of 8.01×10^3 at 12 h, 4.83×10^4 at 1 h, 5.36×10^4 at 1 h, respectively. And the biodegradation rate constants （ka）were 0.00, 0.80×10^-3, 0.30×10^-3 h^-1, respectively. For 0.198 mg· L^-1 DBP, accumulation amount in algal cells was small, which might cause biodegradation to a small extent. For 4.85 mg· L^-1 DBP, it might be higher toxicity of DBP that inhibited algal growth and activity of enzyme.（2 ）At similar initial DBP concentration （about 2.00 mg· L^-1 ）, accumulation amounts of DBP by algae and BCFs at 13 ℃ and 25 ℃ both reached the maxima at 1 h. DBP accumulation in alga and BCFs reached the maxima of 24.0 mg· g^-1DW and 1.23×10^4 at 13 ℃, 85.9 mg·g^-1DW and 4.83×10^4 at 25℃, respectively. And kA were 0.60×10^-3 and 0.80×10^-3 h^-1, respectively. Studies showed that temperature was one of affecting factors, higher temperature was in favor of biodegradation.