Effect of the Acidification Environment on Exchangeable Cations and Acid Buffering Capacity of Weathering Products of Purple Parent Rock
[Objectives]This study aimed to analyze the influence of the acidification environment on weathering products of the typical purple parent rock.The weathering products of purple parent rocks from the Suining Group(J3s),Shaximiao Group(J2s),and Penglaizhen Group(J3p)were investigated under different acidification environments in the laboratory.[Method]The acid solutions used for acidification of purple parent rock samples were used to cycle soaking and simulate leaching experiment tests at pHs of 2.5,3.5,4.5,and 5.6.In addition,deionized water(pH = 7.0)was set as a control treatment(CK).[Result]The results showed that the exchangeable cations and content of total exchangeable cations of weathering products of these purple parent rocks decreased as the acidity of the acidifying solutions increased.The acid buffering capacity of weathering products had an extremely significant correlation with the content of the exchangeable K+,Na+,Ca2+,and Mg2+ and the content total of exchangeable cations(P<0.01).Compared with the value at pH = 7.0(CK),the total content of exchangeable cations of the weathering products of purple parent rock of the groups J3s,J3p,and J2s in cycle soaking experiment tests decreased by 8.75%-18.21%,10.83%-23.18%,and 5.85%-18.41%,respectively.When the amount of simulated rainfall at 24 times was compared with that at 12 times,the total content of exchangeable cations in J3s,J3p,and J2s decreased by 1.77%-24.85%,8.99%-25.75%,and 8.05%-25.66%,respectively.In addition,the exchangeable cations characteristics of the weathering products were Ca2+>Mg2+>Na+>K+ under the same acidity treatment.[Conclusion]The acid buffer capacity,exchangeable salt ions,and total salt of weathering products under the soaking treatment in this experiment were lower than under the leaching treatment.It can be seen that the transport of minerals or nutrients on the slopes of hilly areas is dominated by leaching,while the transport of minerals or nutrients on the plains is dominated by leaching.Therefore,acid deposition may accelerate the occurrence of soil erosion on slopes to some extent,which in turn leads to an acceleration of the plain side process.
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