尾菜再生水灌溉对土壤酶活性与重金属含量的影响

Effects of reclaimed water from vegetable residues irrigation on soil enzyme activity and heavy metals content

为探究尾菜再生水灌溉对土壤酶活性和重金属含量的影响,采用室内土柱模拟试验,分别以尾菜再生水(VW)和自来水(TW)为灌溉水,设置充分灌溉(90%田间持水量,09FC)和非充分灌溉(70%田间持水量,07FC)2个灌水水平,以18 d为1个灌水周期,累计灌溉16期,分别在第72、144、216、288 d进行分层取样,测定土壤过氧化氢酶(CAT)、脲酶(UE)、蔗糖酶(IA)、碱性磷酸酶(ALP)活性及重金属(Pb、Zn、Cr、Cd、Cu)含量的时空变化特征,并对各处理进行相关性分析和潜在生态风险评价。结果显示,与TW-07FC处理相比,长期再生水非充分灌溉0~20 cm土层土壤UE、IA活性分别显著提高了31.36%和6.55%;与TW-09FC处理相比,再生水充分灌溉ALP活性显著提高了15.63%,CAT活性无显著性变化;随着灌溉次数的增加,再生水2个灌水水平均会增加土壤Pb、Cr、Zn含量,但增加效果不显著,土壤Cd含量与自来水灌溉相比无显著变化(P>0.05),土壤Cu含量有降低的趋势;由相关性分析可知,CAT活性与Cu、Zn含量呈极显著正相关关系(P<0.01);IA活性与Cr含量呈显著负相关关系(P<0.05),ALP活性与Zn含量呈显著正相关关系(P<0.05),而与Cd含量显著负相关(P<0.05)。综上可知,再生水长期灌溉可增加0~20 cm土层土壤IA、UE和ALP活性,提高土壤营养素转化率;再生水灌溉能够引起部分重金属元素的累积,但远低于国家标准限定值。

The purpose of this study was to explore the effects of different irrigation treatments on soil enzyme activities and heavy metal contents and to evaluate the potential ecological risks of reclaimed water from vegetable residues(VW)and tap water(TW)to provide a theoretical basis for farmland reuse of reclaimed water from plateau summer vegetable residues.The indoor soil column simulation test was conducted and tap water was used as the control.Two irrigation levels of full irrigation(90%field water capacity,09FC)and inadequate irrigation(70%field water capacity,07FC)were set.An irrigation period of 18 days was used and 16 irrigation periods were accumulated to study the spatial and temporal variation characteristics of catalase(CAT),urease(UE),sucrase(IA),alkaline phosphatase(ALP)activities and heavy metal(Pb,Zn,Cr,Cd,Cu)contents in soil under different irrigation levels of reclaimed water from vegetable residues,and to evaluate the correlation and potential ecological risk.The results showed that compared with TW-07FC,the UE and IA activities in 0~20 cm soil layer under long-term reclaimed water inadequate irrigation were significantly increased by 31.36%and 6.55%,respectively.Compared with TW-09FC,the ALP activity was significantly increased by 15.63%under reclaimed water full irrigation(P<0.05).There were no significant changes in CAT activity(P>0.05).With the increase of irrigation times,the two irrigation levels of reclaimed water increased the contents of Pb,Cr and Zn in soil,but the increasing effect was not significant(P>0.05).Compared with tap water irrigation,the content of Cd in soil had no significant change(P>0.05),and the content of Cu in soil tended to decrease.Correlation analysis showed that CAT activity was positively correlated with Cu and Zn contents(P<0.01).IA activity was negatively correlated with Cr content(P<0.05),ALP activity was positively correlated with Zn content(P<0.05),and negatively correlated with Cd content(P<0.05).In condusion,long-term irrigation with reclaimed water could increase the activities of IA,UE and ALP in 0~20 cm soil,and improve the conversion rate of soil nutrients.Reclaimed water irrigation can cause the accumulation of some heavy metal elements,but it is far below the allowable value stipulated in the soil environmental quality risk control standard for soil contamination of agricultural land.