富里酸对土壤中DnBP的降解及微生物活性的影响

为探究富里酸对有机污染物DnBP的降解和土壤微生物活性的作用,采用土壤培养试验,研究了FA对土壤中DnBP的降解动力学过程及土壤微生物活性的影响规律。结果表明,FA的添加缩短了DnBP的降解半衰期,FA各处理组的半衰期为对照处理的48.1%~67.7%;FA促进了土壤的基础呼吸,40mg g-1处理组促进作用最强,最大CO2释放量为空白对照组的40.87倍;而过氧化氢酶活性则表现出了低浓度FA(10~20mg g-1)促进,高浓度FA(40~160mg g-1)抑制的变化趋势;FA对土壤脱氢酶活性主要表现为促进作用,40~160mg g-1FA对脱氢酶活性促进作用显著。相关分析结果表明FA用量与土壤中DnBP降解率呈正相关,与过氧化氢酶活性呈极显著负相关,与土壤呼吸强度、脱氢酶活性呈极显著正相关。通径分析结果表明FA用量与土壤中DnBP降解率之间有较强的直接效应,还与土壤呼吸强度、土壤酶之间存在间接效应,从而影响DnBP的降解。

Effects of fulvic acid on degradation of DnBP and Microbial activity in soil

Phthalic acid esters commonly exist in agricultural soils in China and it has been determined that the soil is seriously polluted by the high levels of DnBP. Fulvic acid(FA)is a type of dissolved organic matter, which is an important component of soil humus and has a crucial effect on the environmental fate of organic pollutants in the soil. This research was conducted to determine the effects of FA on the degradation of DnBP and soil microbial activity using the mean values from soil culture experiments. The results showed that the addition of FA to the soil shortened the half-life of DnBP during its degradation. The half-life period of DnBP in the FA treatment group was 0.481~0.677 times longer than that in the control treatment. FA promoted the basic basal respiration of soil, whereas the 40 mg·g^-1 treatment group with FA had the strongest promotion effect on soil respiration, which could release CO₂ up to 40.87 times that of the blank control group. Catalase activity exhibited an increasing trend with the low FA concentration(10~20 mg·g^-1)and decreasing in the high FA concentration(40~160 mg·g^-1). FA exhibited an active effect on soil dehydrogenase activity and the 40~160 mg·g^-1 significantly promoted soil dehydrogenase activity. The correlation analysis results showed that the dosage of FA used in soil was positively correlated with the degradation rate of DnBP; however, it was negatively correlated with catalase activity. It was also positively correlated with the intensity of soil respiration and dehydrogenase activity. The path analysis showed that the FA dosage used in the soil strongly affected the direct degradation rate of DnBP in the soil with an indirect effect on the intensity of soil respiration and soil enzymes. Thus, FA affectes the degradation of DnBP.