乐安河洪泛区重金属在水稻作物中分布特征及评价

发布时间：2019-06-14 17:43

【摘要】：耕地受到重金属污染后,在其基础上生长的作物的品质会受到重金属污染的直接影响。人体食用受到污染的作物后,将对人体健康造成较大的危害。为阐明乐安河洪泛区典型监测单元水稻土在污染河水灌溉影响下的重金属分布特征、评价耕地土壤和稻谷重金属污染程度、阐述水稻对土壤重金属元素的吸收、积累的时空变化规律以及水稻对重金属复合胁迫的标志物响应规律。本文根据野外实际条件,选择在不同时空条件下(水稻3个主要的生长期和乐安河洪泛区11个典型监测单元)布设21个样点,分别采集土壤样品和水稻样品,在实验分析和运用指数评价的基础上得出以下主要结论:采用电热板消解法提取土壤中重金属元素Cu、Zn、Pb、Cd、Cr、As,并通过ICP-MS检测出各个样品中的重金属总量值。根据测定数据发现,以江西土壤标准值作为背景值的前提下,以上六种重金属含量的平均值都超出了背景标准,以国家农业用地重金属二级标准作为背景值的前提下,As、Cu、Cd平均值超过标准,Cr、Zn、Pb的平均值未超过标准,表明As、Cu、Cd污染程度较严重。运用Arcgis软件地统计法中的空间插值法分析了以上6种重金属元素总量值在具体各样点处的空间分布特征。发现从村落监测单元来看所有元素高值区主要分布在m:口、兰坑和尚濂,从分区来看,B区和D区的的6种重金属元素浓度都比A、C两区的浓度高,而在用水库水灌溉的样点CK处含量接近江西土壤背景值,表明污水灌溉对土壤重金属污染影响显著。通过聚类分析法得出6种元素的来源相对较单一,主要来源于用于灌溉的污染河水,所有样点归为四大类,与重金属空间分布特征相呼应。在土壤重金属总量分析的基础上,采用单因子和综合污染指数法、污染负荷指数法和潜在生态风险指数法对耕地土壤重金属污染程度进行评价,发现整个区域的污染程度为重度污染,主要污染元素为Cd、Cu和As。通过综合潜在生态风险指数计算出各分区的RI值,结果表明D区属于很强度风险程度,A区和B区属于强度风险程度,仅C区属于轻度风险程度。在对水稻不同生长期以及不同生长部位6种重金属含量测定的基础上,侧重对主要污染元素Cd、Cu、As在水稻主要生长期内和在不同生长部位中的时空分布规律进行分析,结果表明水稻叶片和茎中以上三种元素含量随生长期推进呈现“先降低后升高”的趋势,最高出现在分蘖期。从高、中、低三种浓度水平来看,重金属含量随浓度升高而增长,即高值中值CK。与前面分析的耕地土壤重金属含量做相关性分析,发现水稻生长部位中的重金属含量大小与土壤重金属含量大小成正相关关系。水稻各生长部位重金属富集系数平均值,ZnCdCuCrPbAs,说明Zn、Cd两元素较其它元素更易在水稻稻谷中富集。运用单因子污染指数法和重金属危害总指数HI对稻谷的健康风险进行评价。各元素单因子指数法的评价结果表明,六种元素在一半以上的研究区域样点处均超标,污染程度排序为AsPbCrCuCdZn。健康风险评价结果显示,所有样点的稻谷均对食用者存在较大健康风险,其中m:口、兰坑、尚濂村落的样点处稻谷在食用后甚至存在慢性毒性,分区的总危商系数HI的大小排序为D区B区A区C区。通过图表分析表明,在低水平的重金属胁迫条件下,水稻叶片叶绿素的含量因低剂量刺激效果而升高,也表明水稻叶片的光合性能增加。但超过一定阀值后,会对叶片叶绿素的含量降低。从生长期来看,水稻叶片叶绿素含量总体呈现“先上升后下降”的趋势,平均值大小排序为抽穗期成熟期分蘖期。对叶绿素含量和重金属相关关系分析表明,水稻叶片中的叶绿素含量与土壤中的六种重金属元素含量均呈负相关关系。通过对各样点处成熟期水稻根部和叶片中的SOD、POD、CAT、GSH和MDA五种标志物的测定,结果显示,SOD、POD、CAT、GSH含量随样点处重金属含量的升高,呈现“先上升后下降”的趋势,不同酶含量变化的临界值不同。氧化代谢产物(MDA)的变化趋势则相反,呈现“先下降后上升”的趋势。通过运用综合生物标志物响应指数法对各标志物响应重金属污染压力的研究发现,4个区的IBR值高到低排序是:D区B区A区C区,其中C区属于清洁区域;A区的重金属污染压力较大;D区和B区属于四个区域中污染最重的两个区域。综合叶绿素和以上几种酶含量的响应结果表明,研究区域重金属污染对水稻产生了明显的生理胁迫风险。
[Abstract]:When the cultivated land is polluted by heavy metals, the quality of the crops grown on the ground can be directly affected by heavy metal pollution. When the human body is eaten by the polluted crops, the human body health can be greatly affected. in ord to clarify that characteristic of heavy metal distribution of the typical monitor unit in the flood area of the Le 'an River, the soil and the heavy metal pollution degree of the paddy soil under the influence of the irrigation of the polluted river water are evaluated, and the absorption of the heavy metal elements of the soil on the soil is explained, The change of time and space and the response of rice to the heavy metal complex stress were studied. According to the actual conditions of the field,21 sample points were selected under different time and space conditions (three main growing periods of rice and 11 typical monitoring units in the flood area of the Le 'an River) to collect soil samples and rice samples, respectively. The following main conclusions are drawn on the basis of the experimental analysis and the evaluation of the application index: the heavy metal elements Cu, Zn, Pb, Cd, Cr and As in the soil are extracted by an electric heating plate digestion method, and the total amount of the heavy metal in each sample is detected by the ICP-MS. According to the measurement data, the average value of the above six heavy metal contents exceeds the background standard under the premise that the standard value of the soil of Jiangxi is used as the background value, and the average value of As, Cu and Cd is more than the standard, Cr and Zn in the premise of the secondary standard of the heavy metal of the national agricultural land as the background value, The average value of Pb is not more than that of the standard, indicating that As, Cu and Cd are more polluted. The spatial distribution of the total value of the above six heavy metal elements at various points is analyzed by using the space interpolation method in the Arcgis software geostatistical method. It is found that from the village monitoring unit, the high-value area of all elements is mainly distributed in m: kou, Lankeng Monk, and the concentration of 6 heavy metal elements in the B and D regions is higher than that of the A and C regions, The content of CK is close to the background of the soil in Jiangxi, which indicates that the effect of the sewage irrigation on the heavy metal pollution in the soil is significant. The results of cluster analysis show that the source of the six elements is relatively single, mainly from the polluted river water used for irrigation, and all the samples are classified into four categories, which are in concert with the distribution of heavy metal space. On the basis of the analysis of the total amount of heavy metal in the soil, the pollution degree of the heavy metal in the cultivated land was evaluated by a single factor and a comprehensive pollution index method, a pollution load index method and a potential ecological risk index method, and the pollution degree of the whole area was found to be severe pollution, and the main pollution element was Cd, Cu and As. The RI value of each partition is calculated by the comprehensive potential ecological risk index. The result shows that the D region belongs to the intensity risk level, and the A and B regions belong to the degree of intensity risk, and only the C region belongs to the mild degree of risk. The spatial and temporal distribution of the main pollution elements Cd, Cu and As in the main growth period of rice and the different growth sites was analyzed on the basis of the determination of the content of the heavy metals in different growing periods and different growth parts of the rice. The results showed that the three elements in the leaf and the stem of the rice had the tendency of presenting the "first decrease and then raise" with the growing period, and the highest appeared in the sub-stage. In that high, middle and low concentration level, the heavy metal content increase with the increase of the concentration, i. e. the median value of the high value CK. It was found that the heavy metal content in the growth part of the rice was positively related to the heavy metal content in the soil. The average value of heavy metal enrichment factor, ZnCdCuCrPbAs in each growing part of rice, indicates that the two elements of Zn and Cd are more likely to be enriched in rice paddy. The health risk of rice was evaluated by the single factor pollution index method and the heavy metal hazard total index (HI). The results of the single-factor index method of each element show that the six elements are in excess of the standard and the degree of pollution is AsPbCrCuCdZn. The results of health risk assessment showed that the rice of all the spots had a great health risk to the food, among which, the rice in the spot of the village of m: the mouth, the Lankeng and the other villages had chronic toxicity even after the consumption, and the size of the total risk quotient of the partition was ranked as the C area of the area A in the area B of the D area. The results of the graph show that the content of chlorophyll in the leaves of the rice leaves increased due to the low-dose stimulation in the low-level heavy metal stress condition, and the photosynthetic performance of the rice leaves was also increased. But after a certain threshold, the content of the chlorophyll in the leaves is reduced. In the growing period, the content of the chlorophyll content of the leaves of the rice leaves in general shows the trend of the "first rise and fall", and the average value of the average value is sorted into the maturity stage of the mature period of the heading stage. The relationship between the content of chlorophyll and heavy metals showed that the content of chlorophyll in the leaves of rice was negatively correlated with the contents of six heavy metal elements in the soil. The results showed that the contents of SOD, POD, CAT, GSH and MDA in the root and leaf of rice at various points were determined by five markers. The results showed that the contents of SOD, POD, CAT and GSH increased with the content of heavy metal at the sample point, and the trend of the "first rise and fall" and the critical value of the change of the content of different enzymes were different. The trend of the oxidative metabolism product (MDA) is the opposite, and the trend of the "first decrease and then rise" is presented. By using the comprehensive biomarker response index method, it is found that the high-to-low ranking of the IBR value in the four zones is: Zone A, Zone A, Zone B, Zone B, where the C zone belongs to the clean area, and the heavy metal pollution pressure in Zone A is greater; The D and B areas are the two most heavily polluted areas in the four areas. The results of the response of the total chlorophyll and the above-mentioned enzyme contents show that the heavy metal pollution in the study area has a clear physiological stress risk to the rice.
【学位授予单位】：南昌工程学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;X173

【相似文献】