生物结皮发育对风沙土盐基离子释放和矿物风化的影响

Effects of Biocrusts Development on Base Cations Release and Mineral Weathering in Aeolian Sandy Soil

为探明生物结皮发育对风沙土盐基离子释放和矿物风化的影响,以进一步明确生物结皮的风化成土作用。以典型风沙土上发育的生物结皮为对象,通过模拟淋溶试验比较不同类型生物结皮(藻结皮、藻—藓混生结皮和藓结皮)覆盖土壤的盐基离子释放规律,探究盐基离子释放量随淋溶液pH的变化趋势,以及量化生物结皮覆盖土壤的矿物风化速率。结果表明:矿物风化反应阶段不同种类盐基离子的淋出量均较为平缓,生物结皮覆盖土壤的各盐基离子总淋出量表现为Ca^(2+)>K^(+)>Mg^(2+)>Na^(+),其中藻结皮覆盖土壤的盐基离子总淋出量最高,比无结皮、混生结皮和藓结皮分别增加了112.0%,31.2%,27.1%。淋溶液pH显著影响盐基离子的淋溶释放,且其作用程度因离子种类和结皮类型而异。生物结皮覆盖提升了土壤的易风化矿物含量、风化程度和速率,藻结皮、混生结皮和藓结皮覆盖土壤的风化速率相比无结皮分别提升了61.2%,27.1%,152.6%,并且风化速率随淋溶液pH降低而提升。综上,生物结皮能显著促进风沙土矿物风化,其对风沙土改良和修复具有积极意义。

In order to further understand the weathering and pedogenesis effects of biocrusts,we conducted this study to explore the effects of biocrusts development on base cations release and mineral weathering of aeolian sandy soil.The biocrusts developed on aeolian sandy soil were selected as research subjects,and the simulated leaching experiments were carried out to compare the release regularity of soil base cations under different biocrusts(cyano crust,mixed crust,and moss crust)covering.The variation amount of base cations in leachate with different pH values of leaching solution were explored.We also quantified the weathering rate of soil minerals under biocrusts covering.The results showed that:the leaching amount of base cations in the stage of mineral weathering reaction remained relatively stable.The total amount of different base cations in the leachate of biocrusted soil were Ca^(2+)>K^(+)>Mg^(2+)>Na^(+).The total amount of base cations in cyano crusted soil leachate was the highest.Compared with bare soil,mixed crust,and moss crust,the total amount of base ions in the leachate of cyano crusted soil increased by 112.0%,31.2% and 27.1%,respectively.Additionally,the pH value of the leaching solution significantly affected the leaching of base cations,and its effect varied with the types of cations and biocrusts.According to the mineral weathering characteristics indicated by the release of base cations,biocrusts covering could increase the content,weathering degree and rate of easily weathered minerals in the soil.Compared with bare soil,the weathering rate of soil covered with cyano crust,mixed crust,and moss crust increased by 61.2%,27.1% and 152.6%,respectively,and the weathering rate increased with the decrease of leaching solution pH value.All the above findings showed that biocrusts covering can significantly promote the mineral weathering process of aeolian sandy soil,which is of positive significance to the improvement and restoration of aeolian sandy soil.