模拟酸雨对茶园土壤磷素溶出特征与形态的影响

Effects of simulated acid rain on dissolution characteristics and fraction of phosphorus in tea garden soil

为进一步探讨酸雨与土壤磷素流失之间的内在联系,通过土柱淋溶试验,研究模拟酸雨对茶园土壤磷素溶出动力学特征和形态变化的影响。试验共设置4个处理:T1,pH值为3.5的模拟酸雨;T2,pH值为4.5的模拟酸雨;T3,pH值为5.5的模拟酸雨;CK,pH值为6.5的蒸馏水。结果表明,T1、T2、T3处理的土壤可溶性总磷(TDP)累积溶出量均显著(P<0.05)大于CK处理,增幅分别为17.3%、38.8%、20.4%。T1和T2处理的可溶性有机磷(DOP)累积溶出量显著(P<0.05)大于CK处理。回归分析表明,淋出液中总磷(TP)、可溶性无机磷(DIP)的累积溶出量与淋洗液体积的关系符合一级动力学方程(R^(2)>0.999)。与CK相比,T1、T2、T3处理的DIP最大溶出量分别增加了16.0%、49.9%、16.0%,T2处理的TP最大溶出量增加了13.35%。模拟酸雨淋洗结束后,土壤中NaHCO_(3)提取的无机磷、NaHCO_(3)提取的有效磷的质量分数较CK显著(P<0.05)增加,NH_(4)Cl提取的无机磷、NaOH提取的无机磷、浓盐酸提取的全磷质量分数较CK显著(P<0.05)减少。上述结果说明,酸雨既可以直接促进土壤中无机磷和有机磷的溶出,又能够增加土壤中较高活性磷组分的比例,从而增大土壤磷素流失风险。

In order to explore the internal relationship between acid rain and soil phosphorus loss,the effects of simulated acid rain on phosphorus leaching dynamic characteristics and phosphorus form changes in tea garden soil were studied by soil column experiment.Four treatments were designed in this experiment:T1,simulated acid rain with pH value of 3.5;T2,simulated acid rain with pH value of 4.5;T3,simulated acid rain with pH value of 5.5;CK,distilled water with pH value of 6.5 as control.The results showed that the accumulative dissolution amount of total dissolved phosphorus(TDP)under T1,T2,T3 treatments was significantly(P<0.05)higher than that of CK by 17.3%,38.8%and 20.4,respectively.The accumulative dissolution amount of dissolved organic phosphorus(DOP)under T1 and T2 treatments was also significantly(P<0.05)higher than that of CK.The regression analysis results showed that the relationship between the accumulative dissolution amount of total phosphorus(TP),the accumulative dissolution amount of dissolved inorganic phosphorus(DIP)and the leaching volume fit the first-order kinetic equation(R^(2)>0.999).Compared with CK,the maximum accumulative dissolution amount of DIP under T1,T2,T3 treatments was increased by 16.0%,49.9%and 16.0%,respectively,and the maximum accumulative dissolution amount of TP under T2 treatment was increased by 13.4%.After leaching with the simulated acid rain,the mass fraction of NaHCO_(3) extractable inorganic phosphorus and NaHCO_(3) extractable total phosphorus in tea garden soil was significantly(P<0.05)increased compared with CK,yet the mass fraction of NH_(4)Cl extractable inorganic phosphorus,NaOH extractable inorganic phosphorus,and concentrated hydrochloric acid extractable total phosphorus was significantly(P<0.05)decreased.In general,acid rain could directly promote the release of inorganic and organic phosphorus from soil,increase the proportion of active phosphorus components in soil,and eventually increase the risk of soil phosphorus loss.