不同植被恢复措施对锰尾砂库有机碳及其组分影响

Effects of different vegetation restoration strategy on organic carbon and its fractions in manganese mine tailings pond

探究不同植被恢复措施下锰尾砂有机碳及其组分特征,为锰尾砂库植被恢复措施的选取提供科学依据,于广西桂林某锰尾砂库进行场地试验。本研究以自然植被恢复为对照,设置5种人工植被恢复措施(包括单作:青葙Q、芒草M和长柄山蚂蝗D;以及间作:长柄山蚂蝗-青葙DQ和长柄山蚂蝗-芒草DM)。结果显示,1)人工植被恢复后,尾砂中的总有机碳含量相较于CK增加了15.0%~290%。不同处理总有机碳含量表现为DQ>D>Q>DM>M,DQ处理的有机碳含量达6.94 g kg^(−1)。2)植被恢复使尾砂中易氧化有机碳(EOC)增加了46.2%~258%,可溶性有机碳含量(DOC)增加了259%~519%,微生物量碳(MBC)增加了51.4%~459%,惰性有机碳含量(ROC)增加了10.5%~295%。其中,DQ的DOC、MBC和ROC显著高于D和Q(p<0.05)。3)植被恢复导致尾砂碳库管理指数(CPMI)的增加。具体而言,DQ的增加最为显著,其CPMI较CK提高了236%,并且高于D和Q。而DM的CPMI高于M而低于D。4)冗余分析结果表明,全氮和活性钙对有机碳及其组分的解释量分别达88.8%和83.8%,是植被恢复下调控尾砂总有机碳及其组分的关键因子。综上所述,植被恢复能够有效提高尾砂库的有机碳及其组分含量。其中,长柄山蚂蝗和青葙的间作是适宜的锰尾砂库植被恢复措施。与单作相比,采取合理的间作措施可以提高尾砂库的碳固定效率并改善碳库的质量。研究结果可为修复尾砂库固碳功能和改善尾砂库质量提供参考。

This study investigated the characteristics of organic carbon and its fractions in manganese tailings under different vegetation restoration strategies.It provided a scientific basis for selecting vegetation restoration strategies for the manganese tailing pond.A field experiment was conducted at a manganese tailing pond in Guilin,Guangxi.Five vegetation restoration strategies were set up(Q:Monoculture Celosia argentea L.;M:Monoculture Miscanthus sinensis A.;D:Monoculture Hylodesmum podocarpum H.;DQ:C.argentea and H.podocarpum intercropping;DM:M.sinensis and H.podocarpum intercropping.),and natural vegetation restoration was used as a control(CK).After vegetation restoration,tailings were collected for analysis of total organic carbon and its fractions.The results indicate that:(1)After vegetation restoration,the total organic carbon content in the tailings increased by 15.0%to 290%compared to CK.The total organic carbon content in different treatments was in the order of DQ>D>Q>DM>M,with the DQ treatment reached 6.94 g kg^(−1).(2)Vegetation restoration increased the easily oxidizable organic carbon(EOC)by 46.2%to 258%,dissolved organic carbon content(DOC)by 259%to 519%,microbial biomass carbon(MBC)by 51.4%to 459%,and recalcitrant organic carbon content(ROC)by 10.5%to 295%.Notably,DOC,MBC and ROC in the DQ were significantly higher than those in Q and D(p<0.05).(3)Vegetation restoration led to an increase in the carbon pool management index(CPMI)of tailings.Specifically,the increase in DQ was the most significant,with its CPMI increasing by 236%compared to CK,and it was higher than D and Q.The CPMI of DM was higher than M but lower than D.(4)Redundancy analysis showed that total nitrogen and active calcium explained 88.8%and 83.8%of the variance in organic carbon and its components,respectively,indicating that these are the key factors regulating total organic carbon and its components in tailings under vegetation restoration.In conclusion,vegetation restoration can effectively improve the organic carbon and component content of the tailings.Compared with monocropping,reasonable intercropping strategies increased the carbon sequestration efficiency and improved the quality of the tailings.C.argentea and H.podocarpum intercropping is a suitable vegetation restoration strategy for tailings.The results of this study can provide a reference for enhancing the carbon sequestration function and improving the quality of tailings ponds.