【作者】 陈根；

【导师】 张迎梅；

【作者基本信息】 兰州大学 ， 动物学， 2009， 博士

【摘要】 本论文以土壤线虫作为土壤健康指示生物,结合土壤重金属和有机物污染程度,评估黄河兰州段污染对农田土壤健康的危害程度,从生态功能上揭示农田土壤环境的健康状况。本研究在黄河兰州段设立7个采样点(A样点:甘肃省白银市强湾村西大沟边土壤;B样点:甘肃省兰州市马滩村菜地;C样点:甘肃省白银市强湾村菜地;D样点:甘肃省榆中县建亭村菜地;E样点:甘肃省兰州市青白石村菜地:F样点:兰州大学花园土壤;G样点:甘肃省永靖县刘家峡村菜地),采集土壤,检测土样的基本性质;同时用原子吸收光谱法检测土样中重金属镉(Cd)、铅(Pb)、铜(Cu)、铬(Cr)和锌(Zn)的含量,并计算重金属污染指数(Pi);用气相色谱-质谱法(GC/MS)检测有机物多环芳烃(PAHs)的含量;并分离土壤样本的线虫,计数并鉴定种类,计算土壤线虫生态指数。实验结果如下:1.各样点的土壤湿度、pH值、总氮、C/N和有机质之间存在显著性差异(p＜0.05),土壤呈弱碱性,pH值范围从7.70到7.96;土壤平均湿度范围10.33%-19.30%。2.调查的7个样点的土壤受到被检测重金属Cd、Cr、Pb、Cu和Zn等不同程度的污染,且含量有明显的地理位置差异(p＜0.05);A样点土壤的Cd、Pb、Cu和Zn的含量都明显高于其他采样点(p＜0.05);而G样点土样被检测的重金属含量明显低于其他样点(p＜0.05)。3.根据各样本重金属污染指数,除了G样点,其他样点都受到Cd的污染(Cd污染指数Pi＞1),A样点受到Cd(Cd pi=40.35)的污染最严重。A、C和F样点都受到Pb的污染;A和B样点受到Cu的污染;A、B和F样点都受到Zn的污染;各样点没有发现Cr的污染。G样点没有受到被检测重金属的污染。4.各土壤样本多环芳烃的浓度较低,仅有6种PAH被检测到,包括苯并a蒽、屈、荧蒽、萘、菲及笓等PAHs化合物。A、B和F样点多环芳烃含量高于其它样点(p＜0.05)。5.在7个土样里,总共有29科、53属的土壤线虫被识别。A样点的线虫总数量达到1555.48条/100g土壤,明显高于其它各样点(p＜0.05),在A样点仅检出6科6属线虫;在G样点的线虫数量仅次于A样点,共检出13科20属线虫;B、D、E和F样点线虫总数没有显著性差异(p＞0.05);而C样点线虫总数为177条/100g土壤,明显低于其他样本(p＜0.05)。6.食细菌线虫是各样点中最占优势的食性种群,其在A、B、C、D和E样点等土样中占线虫总数50%以上;A样点的食细菌线虫达到93.30%,明显高于其他样点(p＜0.05);G样点土壤中食植物线虫所占比例最高(p＜0.05);在E和G样点杂食性/捕食性线虫的比例明显高于其他样本(p＜0.05);各样本食真菌线虫的比例较其他食性线虫比例低。7.在所调查的所有土样中,c-p1-2线虫占各样点线虫总数的比例在50%以上;A样点的c-p1-2线虫比例明显高于其他样点(p＜0.05);c-p1线虫在G样点占的比例仅为5.92%,而c-p3～5的线虫占G样点线虫总数的50%以上,明显高于其他样点(p＜0.05)。8.污染严重的样点,其MI、∑MI和H’指数低,反之则高。G样点的MI、∑MI和H’指数明显高于其它样点(p＜0.05);A样点的MI、∑MI、PPI和H’值低于其它样点,但WI高于其他样点(p＜0.05)。在B样点,植物线虫指数(PPI)高于其它样点(p＜0.05)。9.Pi的Cd、Pb、Cu及PAHs含量与∑MI、MI和H’间呈负相关性(p＜0.01),但与WI和PPI呈正相关。本论文结果显示黄河兰州段若干样点土壤受到了重金属和多环芳烃不同程度的污染,但多环芳烃类的污染较轻。土壤污染物在不同程度上影响或改变了土壤线虫的种类、数量、取食性和生态多样性。在土壤污染物胁迫下,线虫的数量、线虫食性结构和线虫土壤定居方式都发生了明显的波动。线虫生态指数与土壤重金属及多环芳烃浓度呈现一定的相关性。因此,线虫群落及其指数可以作为土壤生态健康监测的敏感指标。更多还原

【Abstract】 This study investigated the soil nematode community structure along Yellow River in the Lanzhou area of China,and analyzed the impact of heavy metals(Cd,Pb, Cr,Cu and Zn) and polycyclic aromatic hydrocarbons(PAHs) on the nematode community.Soil samples came from seven locations(A site:Xidagou Drain of Baiyin City, B sites:Matan Village of Lanzhou City,C site:Qiangwan Village of Lanzhou City,D site:Qingbaishi Village of Lanzhou City,E site:Jianting Village of Yuzhong County, F site:Lanzhou University garden and G site:Liujiaxia Village of Yongjing County). The results were showed as follows:1.The sampling sites showed significant differences(p＜0.05) in the moisture of the soil,organic matter,total nitrogen,C/N ratio,and pH.Average soil moisture content ranged between 10.33%and 19.30%.Soil was weakly alkaline,with pH ranging from 7.70 to 7.96.2.It was appeared that the soil samples were mainly contaminated by heavy metals.A significant difference on heavy metals contents in soils was also found in soil samples of different sites(p＜0.05).The highest Cd,Pb,Cu and Zn concentrations were found in site A(p＜0.05) and the lowest Pb,Cr,Cu,and Zn concentrations were found in site G,and Cd even could not be detected in site A.3.In accordance with environmental quality standard for soils(China,GB15618, 1995),all soil samples except site G were polluted by Cd(Pi＞1),especially in site A with PI of Cd equaling 40.35.The soil samples of A,C and F site were polluted by Pb Pi＞1).In site A and B,the soil samples were polluted by Cu.Zn polluted soils of sites A,B and F.In all sites,pollution of Cr was not found.4.Concentrations of PAHs were lower in all soil samples than expected.Among seven sites,only six PAHs were found.In A,B and F,soil sample concentrations of PAHs were higher.Lower concentrations of PAHs were found at other sites.5.A total of 29 nematode families and 53 nematode genera were identified. Population of nematode individuals of A site had a population of 1555.48 nematode individuals in 100g soil,which was significantly higher(p＜0.05) than other sampling sites.At B,C,D and G site,the nematode population densities did not have a distinct difference(p＞0.05).Site C was the lowest in nematode population size among all locations(p＜0.05).6.Bacteriovores were found to be the most abundant trophic group in the study area.A significant location effect was found(p＜0.05) among the bacteria feeder nematodes,reaching a mean maximum of 1451.25(93.30%) at location A.The plant-parasite population was the second most common trophic group in all sites.In sites E and G,the omnivorous-predatory proportions were the highest(p＜0.05). Fungivores nematode taxa were found in low numbers in all trophic groups.7.The nematode quantity of which the c-p value was 1 and 2,occupied over 50% of investigated all nematode population numbers.In site A,the nematode numbers of c-p 1-2 were much more than others locations(p＜0.05).In G sites,numbers of c-p 3-5 nematode population were higher than other sites(p＜0.05),but c-p 1 nematode only occupied 5.92%.8.In heavy pollution sites,∑MI,MI and H’ were low,on a contrary,they were high.In site G,∑MI and MI were the highest(p＜0.05).Site A has the lowest∑MI,MI, H’ and PPI,but the highest WI(p＜0.05).PPI was the highest in site B(p＜0.05).9.Negative correlations were found between Pi of heavy metals(such as Cd,Pb Cu and Zn so on),PAHs and nematode index(such as∑MI,MI,and H’) respectively, but positively correlated with WI and PPI(p＜0.01).The results of this study indicated that heavy metals and PAHs influenced or changed soil nematode diversity and tropical structure.The trophic groups,especially bacterivores and plant parasites,presented big fluctuation with the increase contaminant level.The ecological indexes(such as Diversity Index H’ and MI) were significantly correlated with soil environment condition,concentration of heavy metals and PAHs.Therefore the nematode community and the nematode indexes is a sensitive bioindicator for monitoring pollution by heavy metal and polycyclic aromatic hydrocarbons.更多还原