沙地不同发育阶段的人工生物结皮对重金属的富集作用

生物结皮广泛存在于沙地生态系统,具有重要的生态功能.通过对位于库布齐沙漠腹地达拉特旗火力发电厂附近沙地中不同年代人工生物结皮及物理结皮中重金属含量的测定,旨在分析不同类型生物结皮及物理结皮在不同的发育阶段对重金属富集的影响和重金属污染的指示程度.通过分析和比较,得出以下结论:不同年代生物结皮和物理结皮各种重金属含量均表现为随着发育时间的增加而增加的趋势,生物结皮重金属含量多数类型表现为:Zn＞Cr＞Ni＞Pb＞Cu＞As＞Co＞Cd＞Hg的顺序关系,少数类型表现为:Cr＞Zn＞Ni＞Pb＞Cu＞As＞Co＞Cd＞Hg的顺序关系.通过单因素方差分析(ANOVA),不同年代藓结皮中各种元素差异显著性(P＜0.05)明显低于藻结皮和物理结皮.相同年代生物结皮和物理结皮重金属含量都表现为同样地规律:藓结皮＞藻结皮＞物理结皮,表明相同背景条件下,藓结皮对各种重金属的富集能力明显比藻结皮和物理结皮的富集能力强.通过单因素方差分析(ANOVA),Hg和Ni元素含量在所有相同年代样地的生物结皮和物理结皮均无差异,Cr、Zn、Cu、Co元素含量均存在差异(P＜0.05),但差异有的表现在藓结皮和藻结皮之间,而有的表现为藻结皮和物理结皮之间,而Pb、As、Cd元素含量则表现为有的年代有差异,有的年代无差异.通过污染因子CF值分析,藓结皮对污染的指示作用要明显比藻结皮和物理结皮敏感.同时生物结皮对于重金属的富集具有一定的选择性,像Hg、Ni、Zn、Cu、Pb、Co等元素生物结皮相对富集较少,而像Cr、Cd、As等元素相对富集较多.

Heavy metal contaminant in development process of artificial biological Soil Crusts in sand-land

In sand-land ecological systems, there are wide-spread biological soil crusts which have an important function in the ecological systems. In this study, the heavy metal element contents in artificial biological and physical crusts of different stages were measured in the vicinity of Dalate Thermal Power Plant in Kubuqi Desert to analyze the influence of physical soil crusts and different types of biological soil crusts in different developmental stages upon the ability to accumulate heavy metal and indication of their pollution. The results showed that the contents of various heavy metals increased each year with the increasing of the developmental time of biological and physical crusts of different stages. For most of types of heavy metals in soil crusts, the contents displayed the following sequence as Zn>Cr>Ni>Pb>Cu>As>Co>Cd >Hg, and for a few of types, the contents showed one as Cr > Zn > Ni > Pb > Cu > As > Co >Cd>Hg. One factor analysis of variance (One-way ANOVA) demonstrated that the difference significance (P<0.05) of the various heavy metal contents in moss crusts of different stages was greatly lower than that in the algal and physical crusts. Comparing of the heavy metal contents in the biological crust and physical crusts of the same stage revealed that moss crusts > algal crusts > physical crusts, suggesting that the heavy metal enrichment of moss crusts was greater than that of algal crusts and physical crusts. Through one-way ANOVA, the contents of Hg and Ni in all kinds of biological crusts and physical crusts of the same stage were no significant difference, while the contents of Cr, Zn, Cu and Co were significantly different (P<0.05) in between moss crusts and algae crusts, or in between algae crusts and physical crusts. As for Pb, As and Cd, their contents did not vary significantly with the development stages of different crusts(P<0.05). The contaminant factor (CF) analysis showed that moss crusts were more sensitive than algal crusts and physical crusts for the role of indicating pollution. Meanwhile, biological crusts accumulated the heavy metals selectively. They less likely accumulated Hg, Ni, Zn, Cu, Pb and Co and more likely enriched Cr, Cd and As.