邻苯二甲酸酯污染对黑土转化酶与脲酶反应动力学的影响

采用室内模拟法,以东北黑土为供试土壤,以邻苯二甲酸二甲酯(DMP)和邻苯二甲酸二丁酯(DBP)为代表,采用3,5-二硝基水杨酸法和靛酚蓝比色法测定土壤转化酶和脲酶的活性,研究邻苯二甲酸酯(PAEs)污染对黑土转化酶和脲酶活性及其反应动力学的影响。结果表明,PAEs抑制了黑土中转化酶和脲酶的活性。基于土壤酶活性和PAEs浓度作线性回归,求得黑土轻微污染的临界指标(ED₁₀):DMP污染黑土中转化酶和脲酶的ED₁₀分别为24.352和5.015 mg·kg^-1;DBP污染黑土中转化酶和脲酶的ED₁₀分别为16.911和8.677 mg·kg^-1。根据ED₁₀值越小越敏感的原则,判定黑土中脲酶对PAEs污染比较敏感,可将脲酶活性作为反映PAEs污染黑土的生化指标。DMP和DBP使黑土中转化酶和脲酶酶促反应动力学参数降低,属于反竞争抑制机制。PAEs可能改变黑土的碳氮循环及其生态系统功能,进而影响黑土的可持续利用。

Effect of phthalate esters contamination on urease and invertase reaction kinetics of black soil

The responses of invertase and urease reaction kinetics to phthalate esters (PAEs) were assessed in the northeastern black soil by the indoor simulation method. The enzymatic activities of invertase and urease were measured by 3,5-dinitrosalicylic acid method and indophenol blue colorimetric method, respectively, when dimethyl phthalate (DMP) and dibutyl phthalate (DBP) were used as the test materials. The results suggested that the enzyme activities of invertase and urease were inhibited by PAEs in black soil. Based on the linear regression equation of soil enzyme activities and PAEs concentrations, the critical indicators of the slight contamination (ED₁₀) in black soil were obtained. The ED₁₀ values of invertase and urease for DMP contamination in black soil were 24.352 mg·kg^-1 and 5.015 mg·kg^-1, respectively, and the ED₁₀ values of invertase and urease for DBP contamination in black soil were 16.911 mg·kg^-1 and 8.677 mg·kg^-1, respectively. According to the principle that the smaller ED₁₀ the more sensitive, the results indicated that urease was sensitive to PAEs pollution in black soil and could be used as the biochemical index of PAEs contamination. The kinetic parameters of invertase and urease were decreased by DMP and DBP in black soil, which belonged to the anti-competitive inhibition mechanism. PAEs contamination in black soil might change carbon, nitrogen cycle and the ecosystematic function of black soil, and then affect the sustainable development of black soil.