不同粒径羟基磷灰石对污染土壤铜镉磷有效性和酶活性的影响

Effects of Availability of Cu,Cd and Phosphorus and Soil Enzyme Activities on Contaminated Soils Using Hydroxyapatite with Different Grain Sizes

为研究不同粒径羟基磷灰石对重金属污染土壤的修复效果,采用向污染土壤添加常规磷灰石(150μm)、微米(3μm)和纳米(40 nm)羟基磷灰石的田间原位试验方法,考察其钝化修复5 a后对土壤铜镉磷有效性和酶活性的影响.结果表明:3种粒径羟基磷灰石均提高了土壤p H,降低了土壤交换性酸和交换性铝的含量,且微米羟基磷灰石处理效果最好.常规磷灰石、微米和纳米羟基磷灰石处理分别使w(离子交换态铜)降低了62.6%、74.3%和70.4%,w(离子交换态镉)降低了15.7%、25.3%和26.7%.3种材料均增加了土壤w(TP),其中4.61%~17.4%和73.4%~89.8%分别转化为树脂磷和稳定态磷.微米羟基磷灰石处理分别使土壤脲酶活性和微生物量碳含量提高了4.66和0.66倍.研究显示,微米羟基磷灰石更有利于铜和镉由活性态向非活性态转化,增加土壤磷的有效性,提高土壤微生物活性,在我国南方重金属污染红壤区具有较好的应用潜力.

An in-situ field experiment was conducted to study the effects of ordinary hydroxyapatite( HAP,150 μm), microhydroxyapatite( MHAP,3 μm) and nano-hydroxyapatite( NHAP,40 nm) on the availability of copper( Cu),cadmium( Cd) and phosphorus( P) and soil enzyme activities. The results showed that MHAP had the best efficiency in increasing soil p H and decreasing soil exchangeable acid and aluminum compared with the other amendments. The concentration of exchangeable fraction of Cu was decreased by 62. 6%,74. 3% and 70. 4%,while that of Cd was decreased by 15. 7%,25. 3% and 26. 7%,respectively,in HAP,MHAP and NHAP-treated soils. The three amendments increased soil total P,with 73. 4%-89. 8% transformed into stable-P and only4. 61%-17. 4% changed into resin-P. Moreover,soil urease activities and microbial biomass carbon were 4. 66 and 0. 66 times those in the control. The study showed that MHAP was more effective at transforming Cu and Cd from active to inactive fractions and increasing soil available P and soil microbial activity; therefore,MHAP has good potential for the heavy metal-contaminated red soil in southern China.