添加污泥对尾矿砂理化性质及香樟生理特性的影响

Effects of sewage sludge amendment on physico-chemical properties of mine tailings and physiological responses of Cinnamomum camphora

以香樟作为指示植物,选取黄岩、临海和路桥地区污水处理厂污泥,将污泥与尾矿砂按(污泥质量比例为0%对照、25%、50%和75%)配比进行栽培试验。测定添加污泥对尾矿砂理化性质以及香樟生理特性的影响。结果表明:随着污泥比例的增加,混合基质中的有机质、全氮、全磷明显增加,pH值明显降低,离子交换量明显减少,Cu和Cd总量明显增加,而Pb总量明显减少,Zn总量没有明显变化,Cu、Cd和Zn的DTPA提取量明显增加,而Pb的DTPA提取量明显减少。黄岩和临海污泥在25%和50%比例时,香樟叶和茎的生物量和叶绿素含量明显增加,而根的生物量没有明显变化,在75%比例时,生物量和叶绿素含量均明显减少;而添加路桥污泥使香樟叶、茎和根的生物量和叶绿素含量明显减少。丙二醛含量则与生物量和叶绿素含量呈现相反的变化特征。黄岩和临海污泥在25%和50%比例时,根和叶的Cu、Cd、Pb和Zn含量明显减少,在75%比例时,Cu、Cd和Zn含量则明显增加;而添加路桥污泥使叶和根的Cu、Cd和Zn含量明显增加,Pb含量明显减少。研究表明添加污泥提高了尾矿砂的养分含量,同时改变了其重金属组成,对污泥重金属含量和有机质组成的监控可以准确地预测污泥改良后尾矿砂对植物毒性的变化。

In order to investigate the effects of sewage sludge amendment on physico-chemical properties of mine tailings and physiological responses of Cinnamomum camphora to the mixture,three different sites of sewage sludge （Huangyan （HY）,Linhai （LH） and Luqiao （LQ）） were collected,and then mixed with mine tailings in which the mass percentage of sewage sludge was 0%,25%,50% and 75%,respectively. Results showed that sewage sludge amendment increased the nutrient of mine tailings and changed the heavy metal composition of mine tailings. With the increase of sludge amendment ratios,organic matter,total N and total P were significantly increased,while pH and cation exchange capacity were significantly decreased; total and DTPA-extractable contents of Cu,Cd and Zn except for total Zn were significantly increased,while total and DTPA-extractable contents of Pb were significantly decreased. It can be inferred that the composition of heavy metals in the mixture was related with the original heavy metal characteristics of both mine tailings and sewage sludge. The biomass of leaves,stems and roots,and chlorophyll contents consistently decreased with the increase of LQ sewage sludge amendment ratios,which may be related with the high Cu contents in LQ sludge. The biomass of leaves and stems,and chlorophyll contents of C.camphora grown at 25% and 50% sewage sludge in HY and LH were more than those at control （0）,whereas they were significantly decreased at 75% sewage sludge content. The change of MDA contents,the indicator of biotoxicity,was reverse to those of biomass and chlorophyll. Therefore,the 50% amendment ratios of HY and LH sludge was assumed the best remediate measures due to the least biotoxicity to C.camphora. The biotoxicity had a closely relation with the accumulation of heavy metals in C.camphora. Cu,Cd,Pb and Zn contents of leaves and roots at 25% and 50% ratios of HY and LH sewage sludge were more than those of control （0%）,but Cu,Cd and Zn contents of leaves and roots greatly increased at 75% ratios of HY and LH sewage sludges. However,with the increase of LQ sewage sludge amendment ratios,Cu,Cd and Zn contents of leaves and roots consistently increased,and were more than those of HY and LH sludge treatments. Notably,Pb in the leaves and roots consistently decreased with the increase of LQ sewage sludge amendment ratios,which may be related to the decrease of total and DTPA-extractable contents of Pb. Only in LQ sludge treatments,the Cu,Cd and Zn contents of leaves and roots had positive correlation with their DTPA-extractable contents,respectively,which may be related to different organic matter composition between LQ and other two sludge types. Therefore,heavy metal contents and organic matter composition in the sewage sludge could help to predict the bio-toxicity to plants when mine tailings were amended with sludge.