【作者】 冯宜明；

【导师】 王辉；

【作者基本信息】 甘肃农业大学 ， 森林经理学， 2011， 硕士

【摘要】 本文以金川公司尾矿库生态修复试验地穴换土、直接种植、覆土80cm、覆土50cm、覆土30cm五种栽植措施下5年生柠条为研究对象,采用钻土芯法研究柠条根系对重金属胁迫的响应情况以及不同栽植措施下柠条各器官对镍的吸收特征及规律,探讨土壤与植株体内镍元素的关系以及镍在植株体内的转运积累过程和内外循环的规律,以填补重金属胁迫下根系分布特征研究的不足,同时为利用锦鸡儿属植物治理重金属污染提供理论依据,为干旱和半干旱地区尾矿废弃地的恢复与重建提供造林技术方面的有益借鉴。主要研究结果如下:?1.金川公司尾矿库生态修复试验地土壤中Ni的含量大体呈现出随覆土厚度增加而减小,随土层深度增加而增大的规律。镍平均含量的对比结果为穴换土>直接种植>覆土30cm>覆土50cm>覆土80cm。与甘肃省土壤背景值比较,镍含量严重超标。与土壤环境质量标准三级对比,仅有覆土80cm小区的平均Ni含量在标准之内,其他各区的Ni含量均超标,是标准的4.74～9.20倍。2.在重金属胁迫下,柠条根系长度和有效根长水平方向主要集中在0～50cm。垂直方向主要分布在0～60cm,最大长度集中在0～30cm,之后随深度增加长度逐渐减小。五种栽植措施下单位面积根系总长度及平均有效根长密度的大小顺序均为:覆土50cm>覆土80cm>覆土30cm>穴换土>直接种植。3.不同程度重金属胁迫下,柠条根系生物量的大小顺序为:覆土50cm>覆土30cm>穴换土>覆土80cm>直接种植。水平方向,根系生物量在距树干100cm范围内均有分布;垂直方向,柠条根系生物量随着土层的加深逐渐减小,生物量集中分布在0～50cm层,并且与土层深度存在一定得函数关系;不同径级根系的生物量大小顺序为中根(2.0mm≤DR<8.0mm)>小根(1.0mm≤DR<2.0mm)>毛根(DR<0.5mm)>细根(0.5mm≤DR<1.0mm)。4.有效根重密度的分布大体呈现出随覆土厚度增加而降低的规律,从分布的加权平均值上看,不同栽植措施下柠条有效根重密度顺序为覆土30cm>覆土50cm>覆土80cm>穴换土>直接种植;水平方向各区有效根系干重在距树干1m范围内均有分布;垂直方向有效根重密度亦呈现出随土层深度增加而递减的趋势,集中分布在0～60cm层。5.柠条根系和花中Ni含量较大,而叶和茎中的含量较小。根系Ni含量随直径增加而减小、随土层深度增加而增大,在底层(70cm～90cm)出现含量的最大值。6.不同程度重金属胁迫下,柠条对Ni的吸收量随覆土厚度增加一定程度地降低,吸收量的顺序为:覆土30cm>穴换土>直接种植>覆土80cm>覆土50cm。各器官中,根的吸收量明显高于其它器官,其次是茎、叶,花的吸收量最小。总体而言,覆土30cm下生长的柠条对Ni的吸收量大于覆土较厚和直接栽植等措施下柠条的吸收量,是金川老尾矿库柠条修复较适宜的栽植措施。7.柠条各器官对Ni的富集系数大小顺序为根>花>叶>茎,各试验小区中,Ⅲ区Ni富集系数显著高于其他区,Ⅴ区其次,Ⅳ区最小。8.不同程度重金属胁迫下,Ni的转移系数顺序为覆土80cm>覆土50cm>直接种植>穴换土>覆土30cm,不同部位镍转移系数大体呈现花>叶>茎的顺序。而且转移系数均小于1,是一种较典型的根部囤积型植物。9.从根系对Ni滞留率看,覆土30cm下根系Ni富集较多,很少向茎叶花等地上部分转移,根系滞留率达85.24%;其次是穴换土、直接栽植、覆土50cm,滞留率分别为76.92%、74.96%、61.93%;而覆土80cm下,柠条根系对Ni的滞留效应较弱,滞留率仅为47.27,由根系向地上迁移较多。10.柠条对Ni的吸收和土壤Ni含量的关系并非均呈正相关关系,Ⅰ区柠条叶吸收Ni的能力对土壤环境的依赖性比较大,相关系数为0.993,达到了极显著水平(p<0.01);Ⅴ区柠条茎对Ni的富集受土壤环境影响也比较大,相关系数为0.766,呈显著水平(p<0.05);柠条茎和叶在一些区对Ni的富集能力与土壤Ni浓度呈负相关,其余的相关性未达到显著水平(p>0.05)。更多还原

【Abstract】 Taking the 5-year-old Caragana korshinskii under the soil replacement of planting hole、direct planting、covering soil 30cm、50cm、80cm different planting methods in ecological restoration experimental field of tailings in Jin-chuan as the research object, the paper studied on the absorption feature and laws of each organ of Caragana korshinskii to Ni in the response of root to the heavy metal stress and in different planting measures by using soil coring method, discussed the relationship between soil and element of Ni in the plant and the process of transportation and accumulation and the law of internal and external cycle of Ni in the plant.To fill in the research blank of?root distribution under heavy metal stress.Meanwhile in order to Use Caragana plants which provide theoretical basis for remediation of heavy metal pollution.It provided the helpful reference on restoration and reconstruction of mining wasteland in arid and semiarid regions. The mainly results showed that:1. The content of Ni in ecological restoration experimental field of tailings in Jin-chuan experimental field decreased with the increasing of soil thickness and increased with the increasing of soil depth. The comparison results of Ni contend is soil replacement of planting hole >direct planting>covering soil 30cm>covering soil 50cm> covering soil 80cm. Compared with the soil background value, the content of Ni is over standard seriously. Compared with soil environmental quality standardⅢ, only the district of 80cm covering soil measured up to standard and others is over standard seriously which is 4.74～9.20 times than standard.2. Under Heavy Metal Stress, the root length and the effective root length of Caragana korshinskii in horizontal direction is mainly focus on 0～50cm, and in vertical direction mainly focus on 0～60cm which the maximum length is 0～30cm and the length decreased with the depth since the 30cm. In five planting measures, the order of the total root length and the effective root length density in unit area are covering soil 50cm> covering soil 80cm> covering soil 30cm> soil replacement of planting hole >direct planting.?3.Under Heavy Metal Stress in varying degrees, the order of the root biomass of Caragana korshinskii is covering soil 50cm> covering soil 30cm> soil replacement of planting hole> covering soil 80cm >direct planting. In horizontal direction, the root biomass of Caragana korshinskii distribution in the distance of 100cm from trunk; in vertical direction, the root biomass of Caragana korshinskii decreased with the depth of soil lay increasing; it focused on 0～50cm of soil lay and existing certain functional relationship with the depth of soil lay; the order of the root biomass in different diameter class is nakane(2.0mm≤DR < 8.0mm) >rootlet(1.0mm≤DR <2.0mm)>hair root(DR<0.5mm)>fine root(0.5mm<DR<1.0mm)4. The distribution of effective root density decreased with the increasing of soil thickness. From the distribution of weighted mean, the order of effective root weight density is covering soil 30cm>covering soil 50cm> covering soil 80cm> soil replacement of planting hole >direct planting. Dry weight of effective root distribute in the distance of 1m from the trunk in horizontal direction; effective root weight density was a trend in decreasing with the depth increasing of soil lay and focused on 0～60cm of lay.5. The contend of Ni in root and flower of Caragana korshinskii is larger, but it is less in leaf and stem. The content of Ni in root decreased with the increasing of diameter and increased with the increasing of soil layers depth and appeared maximum in the best primary(70cm～90cm).6. Under Heavy Metal Stress in varying degrees, the uptake of Caragana korshinskii to Ni decreased in certain degree with the increasing of soil thickness and the order of the uptake is covering soil 30cm> soil replacement of planting hole >direct planting> covering soil 80cm>covering soil 50cm. In each organ, the uptake of root is higher than any other organs and the minimum is stem, leaf and flower. Generally speaking, the uptake of Caragana korshinskii of growing covering soil 30cm to Ni is more than the one of the measures of thicker covering soil and direct planting measures, which is the best planting measure of Caragana korshinskii restoration of tailings reservoir in Jin-chuan.7. The order of enrichment coefficient of each organ of Caragana korshinskii to Ni is root>flower>leaf>stem. In each experimental plot, the enrichment coefficient ofⅢis significant higher than others,Ⅴis second andⅤis minimum. 8. The order of transfer coefficient of Ni under Heavy Metal Stress in varying degrees is covering soil 80cm>covering soil 50cm >direct planting> soil replacement of planting hole>covering soil 30cm. The order is flower>leaf>stem in different parts of Ni, the transfer coefficient is less than 1 and this plant is a type of root hoarding plant.9. From the retention ratio of root to Ni, in covering soil 30cm, enrichment of root Ni is more and it transferred seldom toward the aerial part of stem, leaf and flower and the retention ratio of root is up to 85.24%; then the retention ratio of soil replacement of planting hole, direct planting and covering soil 50cm is 76.92%,4.96%,61.93% respectively; in covering soil 80cm, the lagging effect of root to Ni is weaker and the retention ratio is 47.27% which is much more in transferring from root to above-ground.10. Not all relationship is a positive correlation between the absorption of Caragana korshinskii to Ni and the content of soil Ni. The dependence is quite large inⅠdistrict of absorptive capacity of Caragana korshinskii leaf to Ni for soil environment and the correlation coefficient is 0.993 which is very significant(p<0.01); the effect is large inⅤdistrict that soil environment for enrichment of Caragana korshinskii stem to Ni and the correlation coefficient is 0.766 which is significant(p<0.05); the relationship had a negative correlation between enrichment ability of Caragana korshinskii stem and leaf to Ni and concentration of soil Ni in some district and the other correlation are not up to significantly(p<0.05).更多还原