海鲜壳生物质炭对酸性土壤的改良效果与机制探究

Improvement Effects and Mechanisms of Seafood Shell Biochars on Acidic Soils

以花甲、扇贝、生蚝、青口贝4种市场产量大且壳生物量高的海鲜壳为原材料厌氧热解制备生物质炭作为改良剂,以我国南方红黏土、红砂土、砖红壤3种主要典型酸性土壤为供试土壤,探究海鲜壳炭最佳制备条件及其对我国酸性土壤的改良效果与机制。结果表明:高温条件下制备的海鲜壳炭主要成分是CaO和CaCO_(3),同时含有NaO、MgO等碱性物质,碱含量极高。热解温度对4种海鲜壳炭碱含量影响巨大。800℃是制备海鲜壳炭的最佳温度,此时其碱含量已达到甚至超过石灰的水平,同时保留部分–OH等多种官能团,比石灰更稳定,且含有比石灰更少的致酸物质。800℃制备的海鲜壳炭可以大幅度提高我国南方酸性土壤pH、固相吸附态羟基铝含量、阳离子交换量和酸缓冲容量,降低土壤溶液铝和交换态铝含量,土壤固相有机结合态铝含量呈上升趋势。800℃制备的海鲜壳炭是可以替代传统石灰的理想酸性土壤改良剂,可以有效缓解石灰资源压力并降低改良成本。本研究成果对于酸性土壤改良成本降低及海鲜壳废弃物资源化利用均具有重要指导意义。

In this study,four kinds of seafood shells were used as raw materials by anaerobic pyrolysis to produce biochars and three typical acidic soils in south China were used as test soils to explore the best preparation conditions of seafood shell biochars and their improvement effects and mechanisms on acidic soil.The results showed that the main components of seafood shell biochars prepared at high temperature were CaO and CaCO_(3),and simultaneously containing alkaline substances such as NaO and MgO,meanwhile the alkali content were very high.Pyrolysis temperature had great influence on the alkali content in the biochars,800 was the best temperature for preparing the biochars,at this time the alkali content reached or℃even exceeded lime,while retaining some of the functional groups such as–OH,which was more stable than lime,and containing less acid substances than lime.The biochars prepared at 800℃significantly promoted acidic soil pH,solid phase adsorbed hydroxyl Al,cation exchange capacity and acid buffer capacity,decreased the contents of soil solution Al and exchange Al,and increased the contents of soil solid phase organically bound Al,which is an ideal acid soil amendment replacing traditional lime,can effectively relieve the pressure of lime resources and reduce the improvement cost.The results of this study have important guiding significance for reducing the cost of acid soil improvement and resource utilization of seafood shell waste.