【作者】 杨丹；

【导师】 祁士华；

【作者基本信息】 中国地质大学 ， 环境科学与工程， 2012， 博士

【摘要】 有机氯农药(organochlorine pesticides,简称OCPs)是一类典型的持久性有机污染物(persistent organic pollutants,简称POPs),具有半挥发性、持久性和高毒性,并能通过食物链在生物体中富集。有机氯农药可以在不同的环境介质间迁移,并能在大气环境中进行远程传输,导致大范围乃至全球性的环境污染。早在20世纪70年代,西方发达国家就认识到有机氯农药在环境中的残留危害而禁止对其的使用,随后我国也在1983年禁止了有机氯农药的生产和使用。但由于有机氯农药的使用量大,而它们的难降解和持久性特征使得这些有机氯农药在环境中降解缓慢、滞留时间长,因此,有机氯农药仍然属于环境中检出率最高的一类持久性有机污染物。海湾是连接海洋与陆地并进行海陆交互作用最为频繁的地带,也是人类生存与发展过程中不可或缺的重要地域。但是由于海陆交互作用下汇水盆地向海湾输入的污染物在湾内形成沉淀,导致污染物在海湾及河口沉积物中富集而形成高含量区域,尤其是在有机污染物含量较高的情况下所引起的底栖生物的富集放大现象,都会加剧海湾及河口地区的有机污染。由此可见,了解汇水盆地与其所对应的海湾地区之间的污染输送情况,对于分析海湾污染现状,评估海湾生态风险尤为重要,同时也能为海湾污染的治理指明方向。晋江流域位于福建省东南部,流域面积5629km2,占全省面积约5%。该流域经济发达,十多年来经济总量一直处于福建第一。泉州湾位于福建省东南部沿海、台湾海峡西岸,西迎晋江,北纳洛阳江,属于半封闭式海湾。由于洛阳江的径流量和输沙量均较小,因此,晋江成为向泉州湾输送物资的主要河流,而晋江流域也成为泉州湾污染输入的重要源区。本研究以晋江流域对泉州湾的有机氯农药传输为例,建立有机氯农药的环境多介质逸度模型,研究汇水盆地对海湾的有机氯农药的一对一的输送过程,同时,对泉州湾沉积柱中有机氯农药的沉积历史进行研究分析,并结合多介质逸度模型的模拟结果,对晋江流域和泉州湾的污染历史储量进行估算。论文的第一部分建立了福建晋江流域对泉州湾输送有机氯农药的多介质逸度模型,对基于陆海输送的有机氯农药的地球化学行为与归宿进行了相关研究。本文构建的非平衡、稳态、流动系统模型包括大气相、水相、沉积物相和土壤相四个区间环境相,每个环境相又包含若干子相,如大气相中包含了大气颗粒物子相和气相子相,水相中包含了悬浮颗粒物子相、生物子相和水体子相等等,旨在对研究区环境作出较为全面客观的描述。为了明确研究所构建的模型能否客观地描述有机氯农药的多介质环境行为,本研究将有机氯农药在环境介质中的实际摩尔浓度值,与模型进行多介质模拟后得出的摩尔浓度值作对比验证,结果显示水体、沉积物和土壤相中有机氯农药的模拟值与实测值吻合较好,浓度残差都在1个对数单位内,可见该模型在模拟晋江流域对泉州湾有机氯农药的传输、以及有机氯农药最终在泉州湾的分布和归趋方面与实际情况有着较好的一致性。通过模型对有机氯农药在环境介质中的储量模拟结果显示,HCHs和DDTs在环境介质中的储量分布情况不同,DDTs更容易蓄积在沉积物中,而HCHs蓄积最多的环境介质则为土壤。由此可见,土壤和沉积物对有机氯农药的储存能力明显高于水体和大气,因此,土壤相和沉积物相是OCPs在本研究系统环境中的主要储存介质。对有机氯农药的环境迁移过程模拟结果显示,系统达到稳定状态时,HCHs从水体向大气的迁移通量最大,达到1.44kg/a,而DDTs从水体向沉积物的迁移通量最大,达到29.6kg/a。HCHs和DDTs从大气向土壤的传输通量均大于大气到水体的传输通量,HCHs由水体向大气的迁移通量要大于水体向沉积物的传输通量,DDTs则正好相反。对于土壤相而口,HCHs和DDTs向水体的传输通量要明显大于其向大气的传输通量。由于土壤向水体的传输主要体现在水土流失对海湾的供给,可见,对于晋江流域土壤中残留的有机氯农药以地表径流的方式进入泉州湾的传输通量是不容忽视的。有机氯农药在大气相中以大气的平流输出和降解为主,伴随着少量向土壤和水体的迁移；水相中以洋流的平流输出和水体向大气和沉积物的迁移为主,伴随着少量的降解；土壤相中,以土壤的降解为主,伴随着少量的向水体和大气的迁移；沉积物相中则以沉积物的深层掩埋为主,伴随着一定量的降解过程和少量的再悬浮过程。为了评估模型中的输入参数对模型输出结果的影响,以及可能造成结果输出的可变性,本研究对模型各参数作了灵敏度分析。结果显示,化合物的辛醇-水分配系数对数logKow对HCHs和DDTs在研究区各环境相中的浓度影响最大,即对模型模拟结果影响最强烈。论文第二部分进行了泉州湾有机氯农药的高分辨率沉积记录的研究。根据泉州湾内湾和外湾沉积柱中210Pb的放射性比活度的垂直分布情况,通过恒定沉积能量模式(Constant Initial Concentration, CIC)计算得到泉州湾内湾(QZ1)和外湾(QZ2)沉积物的平均沉积速率分别为1.23cm/a和0.55cm/a,同时通过稳定初始放射性通量模式(Constant Rate of Supply, CRS)计算得到了沉积物在不同深度的沉积速率,从而得到泉州湾内湾(48cm)和外湾(32cm)沉积柱的沉积年代分别追溯到1953年和1948年。根据泉州湾内湾及外湾沉积柱各沉积层的有机氯农药的浓度含量,通过计算得到有机氯农药在两处沉积柱中的沉积年代序列情况。QZ1中HCHs的沉积通量在1950-1960年间出现了一个高峰,与我国在50年代初期农药使用量较小的实际情况有一定出入,可能由于内湾沉积环境较不稳定而出现了较大的扰动作用所致。QZ2中HCHs在1965～1970年出现了高峰值,与我国上世纪60～70年代大量使用六六六类农药较为吻合。QZ2中HCHs和DDTs在1985～1992年间均出现了高峰,究其原因应该是泉州湾在上世纪80年代中期实行的大面积滩涂围垦和毁林造田活动,使得大量残留了有机氯农药的土壤被地表径流携带进入泉州湾沉积下来所造成。泉州湾内湾沉积柱中OCPs的沉积通量低于外湾沉积柱中的沉积通量,而内湾沉积物的平均沉积速率(1.23cm/a)比外湾沉积物的沉积速率(0.55cm/a)要高,出现这种现象的原因可能有两点,一是由于内湾沉积环境较不稳定可能存在一定的环境扰动,影响了OCPs的沉积；二是外湾沉积物可能接受了来自外海回流的污染输入,从而形成这样的差别。通过对泉州湾沉积柱中DDTs的沉积通量与福建晋江流域山区和泉州湾沿海地带的温度和降水情况、以及晋江输沙量等水文和气象数据的逐年统计情况作相关性分析,结果显示,DDTs的沉积情况与上述环境要素相关性很弱。对泉州湾OCPs沉积定年结果的不确定性分析得到,210Pb定年方法的不确定性和OCPs在沉积过程发生垂向位移的不确定性,可能会使泉州湾OCPs的沉积年代序列产生误差而与实际沉积年代不相符。论文第三部分进行了晋江流域对泉州湾有机氯农药污染的历史估算。晋江流域作为向泉州湾输送物资的重要源区,其对泉州湾造成的污染影响其实是其自身的污染写照。通过对沉积柱中有机氯农药含量等信息的解读,我们就能利用多介质逸度模型的相关结论,在一定程度上获取晋江流域的历史污染信息以及泉州湾受到晋江流域影响而形成的历史污染状况。因此,通过多介质环境逸度模型中所得到的OCPs在各环境介质中的储量占环境体系中OCPs总储量的比例,建立研究系统保持稳态比例输出的假设,将泉州湾沉积柱中OCPs的沉积序列通量作为数据源,对晋江流域和泉州湾有机氯农药的污染历史储量进行估算。对50年代至80年代HCHs和DDTs在晋江流域土壤、大气、泉州湾水体、沉积物中的储量以及研究区环境总储量的估算结果显示,泉州湾沉积物中HCHs和DDTs在50年代、60年代、70年代和80年代的储量分别为4.61kg和16.67kg,5.91kg和9.18kg,3.67kg和30.45kg,7.99kg和115.78kg。通过换算得到50年代、60年代、70年代和80年代,研究区,即晋江干流流域至泉州湾总环境体系中HCHs和DDTs的储量分别为25.00kg和16.74kg、35.07kg和9.22kg、23.02kg和30.56kg、47.70kg和116.23kg；研究区晋江流域土壤中HCHs和DDTs的储量分别为19.60kg和0.06kg、28.04kg和0.03kg、18.65kg和0.08kg、38.27kg和0.35kg;大气中HCHs和DDTs的储量分别为5.24g和0.24g、7.00g和0.09g、5.47g和0.33g、10.48g和1.16g；泉州湾海水中HCHs和DDTs的储量分别为0.79kg和0.02kg、1.11kg和0.01kg、0.70kg和0.03kg、1.43kg和口0.10kg。总体而言,HCHs在各环境介质中年代储量顺序基本为80年代>60年代>50年代>70年代,DDTs则为80年代>70年代>50年代>60年代。可见,二者在环境中的储存情况较不相同,可能与福建省或晋江流域在各年代所施用的有机氯农药的种类和数量有所差异有关。估算得到的研究区总环境中HCHs的储量水平与研究区HCHs的总施用量水平相差1-3个数量级。验证结果存在差异的原因主要为多介质环境逸度模型对环境系统稳态的假设以及系统保持稳定输出的假设所产生的误差、泉州湾沉积柱OCPs定年结果的不确定性所产生的误差和研究区HCHs施用量实际值选取的误差。更多还原

【Abstract】 Organochlorine pesticides (OCPs) are typical persistent organic pollutants (POPs), with characters of half-volatility, persistence, and high toxicity in the environment, and biological accumulation through the food web. OCPs are able to migrate between the different environmental media, proceed to long-range transport in the air, and lead to global environmental problems. In the early1970s, western developed countries had prohibited the use of OCPs as having recognized the hazard of OCPs residual in the environment. And in the following1983, the production and usage of OCPs were also banned in China. However, OCPs are still the most widespread POPs in the environment, due to their large use amount and slow degradation.The bay is not only the most important area for the connection and interaction between land and sea, but also the indispensable region for human survival and development. However, pollutants input to the bay from the interactions of land and sea would enter into the sediment of bay, and lead to the contaminants enrichment, especially the benthos amplification in the case of high concentrations of organic pollutants, which may exacerbate the organic pollution in the bay. Thus, having the information about the pollution transport between the bay and its catchment watershed is helpful and important to analyse the pollution status quo, assess the ecological risk, and control the pollution of the bay.Jinjiang River watershed is located in the southeast of Fujian Province, with the area of5629km2, accounted for5%of the whole province area, approximately. The economy of this watershed region is developed and the economic aggregate has been the highest in Fujian more than a decade. Quanzhou Bay is a semi-enclosed bay in the southeast coast of Fujian Province, adjacent to the west side of the straits of Taiwan. Jinjiang Rive and Luoyangjiang Rive inject into Quanzhou Bay from west side and north side, respectively. Compared with Luoyangjiang Rive, Jinjiang River is more important to Quanzhou Bay for offering more runoff and sand to the bay every year. And Jinjiang River watershed has also become the most important source region of pollution input to Quanzhou Bay.In this study, Jinjiang River watershed and Quanzhou Bay were selected as our case study to establish a multi-media fugacity model of OCPs to discuss the transport of OCPs from the watershed to the bay. And the historical trends of OCPs in sediment cores in Quanzhou Bay were studied. Combined with the simulation results of the multi-media fugacity model, this research attempted to estimate the historical pollution reserves of the Jinjiang River watershed and Quanzhou Bay.In the first part of this thesis, a multi-media fugacity model on the transport of OCPs form Jinjiang River watershed to Quanzhou Bay was established, which was used to study the geochemical behavior and the fate of OCPs from land to sea. In order to provide a more comprehensive and objective description of environment in the study area, the non-equilibrium, steady-state flow system model was built in this thesis including four environmental compartments (air phase, water phase, sediment phase and soil phase), and each compartment had a number of sub-cells, such as the air phase including air particle and air sub-cells, water phase including particle, biont and water sub-cells and so on. In order to know whether this model was suitable for this study, the molar concentrations of OCPs from the actual test were compared with the simulation value of OCPs molar concentrations. And the results showed that the value from the actual test and model simulation in water, sediment and soil phase were in good agreement, and concentration residuals were all less than one logarithmic unit. So, this model was able to perform the suitable simulation on the transport of OCPs from Jinjiang River watershed to Quanzhou Bay, as well as the distribution and fates of OCPs in Quanzhou Bay. The model results showed that the reserves distribution of HCHs and DDTs in environmental media were different. DDTs mostly accumulated in sediments, whereas HCHs prefered to accumulate in soil, compared with other environmental media. Thus, the storage capacities of soils and sediments for OCPs were significantly higher than water and air, and therefore, soils and sediments were the main storage media for OCPs in the environment in the study system.Modeling results of environmental migration indicated that the migration flux of HCHs from water to atmosphere was the highest (1.44kg/a), while the migration flux of DDTs from water to sediment was highest (29.6kg/a), when the system reached steady state. The migration fluxes of HCHs and DDTs from air to soil were both higher than the fluxes from air to water. The fluxes of HCHs from water to air were higher than the fluxes from water to sediment, while DDTs were on the opposite. For the soil phase, fluxes of HCHs and DDTs from soil to water were higher than to the air. As the transport from soil to bay water is mainly reflected in the supply of soil erosion to the bay, the transport of OCPs through the surface runoff from the Jinjiang River watershed to Quanzhou Bay was significant. In the air phase, the mainly behaviors of OCPs were atmospheric advection and degradation, with a small amount of migration to the soil and water phase. In the water phase, the mainly behaviors of OCPs were ocean current advection and migration from water to air and sediment, with degradation in a small amount. In the soil phase, the mainly behavior of OCPs was degradation, with a small amount of migration to the water and air. In the sediment phase, the mainly behavior of OCPs was to deep bury, with a small amount of degradation and resuspension.In order to assess the influence of the model input parameters to the model results, this study made sensitivity analysis of model parameters. The analysis showed octanol-water partition coefficient logarithm had greatest impact on the model outputs of HCHs and DDTs concentrations in various environmental phases of the study area, namely this parameter had the strongest influence on the modeling results.In the second part of this thesis, the high-resolution sedimentary records of OCPs in Quanzhou Bay were studied. With the information about the vertical distribution of radioactive activity of210Pb in the inner bay (QZ1) and outer bay (QZ2) of Quanzhou Bay, a constant initial210Pb concentration (CIC) model was used to give average sedimentation rates, the results were1.23cm/a in QZ1, and0.55cm/a in QZ2. And a constant rate of210Pb supply (CRS) model was applied to date each slice of sediment to obtain that QZ1(48cm) and QZ2(32cm) dated back to1953and1948, respectively.Historical trends of OCPs in Quanzhou Bay were obtained by applying the concentration of OCPs in each sediment slice back to the age sequence of sediment cores. There was a peak of deposition flux of HCHs in QZ1between1950and1960, but in the1950s, the use of pesticides in China was not in such high level, and this discrepancy might due to the heavy disturbance in inner bay with instable environment. A peak deposition flux of HCHs was found between1965and1970in QZ2, which was consistent with the heavy use of HCHs in1960s in China. The fluxes of HCHs and DDTs both showed peak values between1985and1992, which mainly because of the large-scale of beach reclamation and deforestation with farmland reclamation in the area of Quanzhou Bay in the mid-1980s, which allowed a lot of soil and surface runoff with OCPs residuals were carried into the Quanzhou Bay and deposited in the sediments.The deposition fluxes of OCPs in inner sediment core were lower than in outer one, whereas the sedimentation rates in inner core were higher than the rates in outer one. The reasons for this phenomenon might be from two aspects. Firstly, the depositional environment of inner bay was instability with many disturbances to affect the deposition of OCPs. Secondly, the outer bay might receive the pollution inputs from the outer sea water.The weak correlation were found between the deposition of DDTs and environmental factors, by the comparison and correlation analysis between the OCPs deposition chronological sequence and the historical hydrological and meteorological datas in mountain area of Jinjiang River watershed and coastal zone of Quanzhou Bay, such as temperature, precipitation and sediment load.Uncertainty analysis for the OCPs deposition chronological sequence showed the uncertainty of the210Pb dating method and the OCPs deposition process both might lead to the results not match the actual deposition ages of OCPs in this study.In the third part of this thesis, the historical reserves of OCPs in Jinjiang River watershed and Quanzhou Bay were estimated. Jinjiang River watershed is the most important area to deliver supplies to the Quanzhou Bay. And the pollution in Quanzhou Bay is the portrayal of the contamination in Jinjiang River watershed. With these information and several results from the multi-media fugacity model, the historical contamination fluxes of OCPs from Jinjiang River watershed to Quanzhou Bay could be work out. Therefore, based on the assumption of steady ratio of output in the research system, the proportions of OCPs reserves in individual environmental medium to the total reserves of the research system could be gained from the fugacity model of multi-media environment. With these proportion values and the OCPs deposition chronological sequence, the historical reserves of OCPs in Jinjiang River watershed and Quanzhou Bay were attempted to estimate.Total historical reserves of soils, atmosphere, water, sediment and the whole environment in Jinjiang River watershed and Quanzhou Bay in1950s,1960s,1970s,1980s were estimated. The results revealed that the reserves of HCHs and DDTs in the sediment of Quanzhou Bay in1950s,1960s,1970s,1980s were4.61kg and16.67kg,5.91kg and9.18kg,3.67kg and30.45kg,7.99kg and115.78kg. So the reserves of HCHs and DDTs in the whole stuty area in1950s,1960s,1970s,1980s were25.00kg and16.74kg,35.07kg and9.22kg,23.02kg and30.56kg,47.70kg and116.23kg, respectively. The reserves of HCHs and DDTs in the soil of the Jinjiang River watershed were19.60kg and0.06kg,28.04kg and0.03kg,18.65kg and0.08kg,38.27kg and0.35kg, respectively. The reserves of HCHs and DDTs in the air phase of study area in1950s,1960s,1970s,1980s were5.24g and0.24g,7.00g and0.09g,5.47g and0.33g,10.48g and1.16g, respectively. The reserves of HCHs and DDTs in the sea water of Quanzhou Bay in1950s,1960s,1970s,1980s were0.79kg and0.02kg,1.11kg and0.01kg,0.70kg and0.03kg,1.43kg and0.10kg, respectively.Overall, the historical reserves of HCHs and DDTs in various environmental media in the study region were basically in the order that1980s>1960s>1950s>1970s and1980s>1970s>1950s>1960s, respectively. The historical reserves orders of HCHs and DDTs were found different in this study, and the reason maybe the different types and quantities of pesticides were applied in different years. The estimated reserves of DDTs in the whole study area were one to three orders of magnitude less than the application amount of OCPs on the study area. The main reasons of this discrepancy were from the errors of the assumption of steady state in multi-media environmental fugacity model and the stable proportion of output reserves, the uncertainty from OCPs deposition chronological sequence, and the chose of actual values of OCPs application amount in the study area.更多还原