Distribution and sources of organochlorine pesticides in sediments of the coastal East China Sea     

Lin T  Hu L  Shi X  Li Y  Guo Z  Zhang G 《Marine pollution bulletin》2012,64(8):1549-1555

Forty-two surface sediment samples collected from the southern coastal East China Sea (ECS) were analyzed for organochlorine pesticides (OCPs). The results showed high concentrations of DDTs and parent DDT fractions in the nearshore area, suggesting that there is still a fresh input of these species from non-point sources, probably due to the recent usage of relevant products. However, for HCHs, the high concentrations with elevated β-HCH fraction were focused at the local major river estuaries, indicating that soils-released HCH input was mainly from the major river runoffs. The distribution and composition of OCPs in the coastal ECS could be more prominently controlled by the direct regional inputs rather than the general natural sorption process on particulate organic carbon. DDTs and chlordane are more important for their potential ecotoxicological risk on neighboring benthic community in the nearshore region and the local major river estuaries.  相似文献   

Understanding the Biogeochemical Process and Mechanism of Ecosystem Carbon Cycle from the Perspective of the Earth's Critical Zone     

Xuefa Wen  Xinyu Zhang  Jie Wei  Sidan Lü  Jing Wang  Changhua Chen  Xianwei Song  Jingyuan Wang  Xiaoqin Dai 《地球科学进展》2019,34(5):471-479

Previous research rarely considers the biogeochemistry process of the whole rock weathering layer-soil profile. The aim of Critical Zone science is re-understanding the structure and function of ecosystems from the canopy to bedrock, which emphasizes the relationship of material and energy between atmosphere and plant, between plant and soil, between soil and river in small watershed on the watershed scale. Carbon fixation and allocation are the key starting processes. Decomposition and transformation of soil carbon are the key turnover processes. Carbon migration and balance in small watershed are the key transfer processes. Further research is needed in the process, mechanism and ecology function of ecosystem carbon cycle from the canopy to bedrock based on the watershed scale. Carbon isotope technology has the function of indication, tracing and integration. Based on the ¹³C natural tracing and artificial labelling methods, we can further understand the process and mechnism of carbon biogeochemistry.  相似文献   

Geochemical and Sr‐Nd‐Hf‐Pb Isotopic Constraints the Petrogenesis and Origin of Basalts from the Southern Okinawa Trough     

Quanshu YAN  Xianwei MENG  Xuefa SHI 《《地质学报》英文版》2019,93(Z2):116-119

  相似文献   

Sources,geochemical speciation,and risk assessment of metals in coastal sediments: a case study in the Bohai Sea,China     

Ningjing Hu  Jihua Liu  Peng Huang  Shijuan Yan  Xuefa Shi  Deyi Ma 《Environmental Earth Sciences》2017,76(8):309

To investigate the sources and toxicity of metals in Bohai Sea sediments, concentration and geochemical speciation of metals of surface sediments were measured. Metal distributions and principal component analysis suggested that Zn, Pb, Cd, and Ag were largely derived from anthropogenic sources, whereas the majority of the other metals studied here were found to have been derived from natural rock weathering and calcareous marine biota. The major sources of anthropogenic metal inputs to the study region are from the mining industry, port transport services, vehicle exhausts, and agricultural runoff. Empirical sediment quality guidelines and the risk assessment code were used to evaluate the metal toxicities in this area. Our results show that Cd presents a high risk to the ecological system because it was found in the non-residual phase, which tends to be weakly bound and highly bioavailable; Cu, Pb, Ni, and Co pose a low risk; Zn and Cr present no risk. The use of the threshold effects level and effects range-low values of Cd and Cr as guidelines for the Bohai Sea are of limited use as they do not account for the bioavailability and toxicity of the elements in marine environments. Assessment of the annual metal fluxes from riverine and atmospheric sources indicates that the largest contributions of metals to the Bohai Sea were derived from the suspended particulate load of rivers. Furthermore, it was found that the main depositional zones for metals in the Bohai Sea were in estuaries and the center mud zones.  相似文献   

渤海沉积记录的末次冰期千年尺度古环境与古气候变化   总被引：1，自引：0，他引：1  

方文丽  姚政权  石学法  葛晨东  乔淑卿  李小艳  董智  王颖 《海洋地质与第四纪地质》2019,39(3):61-71

末次冰期千年尺度古气候变化事件在全球大部分载体中均有不同程度的记录,但在海岸带-陆架区的沉积记录中该事件还未见有报道。对取自渤海的BH08孔上部26m的岩芯进行了高分辨率粒度测试与分析,结合AMS 14C测年结果和微体古生物特征,探讨了研究区末次冰期以来古环境和古气候变化。运用粒级-标准偏差法对粒度数据进行研究,发现BH08孔敏感组分(88.4~148.7μm)的变化记录了末次冰期D-O(Dansgarrd-Oeschger)旋回冷暖事件:在暖期时敏感粒级粗组分(88.4~148.7μm)的含量低,而在冷期时含量高,且可以与反映东亚夏季风的指标对应。在暖期时,强盛的夏季风带来丰富的降水,增加的径流可以将粗粒沉积物搬运至更远的下游区,且暖湿气候有利于植被的发育,使得流域内粗粒沉积物减少;而在冷期呈现相反的变化趋势。我们推测,在末次冰期低海面的背景下,格陵兰和北大西洋等高纬地区气候变化导致大气环流和/或洋流系统发生改变,从而对东亚夏季风降水的调控造成河流输入物质的变化可能是造成BH08岩芯敏感组分变化的主要原因。  相似文献   

富钴结核粒径分形特征     

崔迎春  石学法  刘季花 《海洋湖沼通报》2008,(3)

利用分形理论,对我国在中、西太平洋国际海底区域获得富钴结核的粒径特征进行了研究.结果显示富钴结核的粒径具有分段分形的特点,计算得到了它们的各自的分维数,并对其意义进行了探讨.  相似文献   

南海西北部89PC柱样沉积物中浮游有孔虫特征及其古环境意义     

李小艳  翦知湣  石学法  陈志华  程振波  吴永华  石丰登 《海洋地质与第四纪地质》2009,(3)

对南海北部89PC柱状样进行了浮游有孔虫定量统计分析、氧碳同位素测试、碳酸钙含量分析和AMS14C测年,并采用古生态转换函数计算了表层海水古温度和温跃层深度,揭示了该海区约127 ka以来的古海洋学特征。温跃层转换函数计算的温跃层深度结果表明,在MIS5-MIS4期,温跃层深度没有大的变化,在MIS3-MIS1期,温跃层的深度逐渐变深。古温度转换函数计算的古温度结果表明,夏季温度的变化范围为27.9~29.3℃,变化幅度为1.4℃,冬季温度变化范围为20.6~26.3℃,变化幅度为5.7℃。与南海南部的冬夏古水温资料进行对比,南海南部的温度比南海北部的温度要高,这种差异在冬季时表现更为突出,且在冰期时南海南部和北部的温度差异梯度进一步增大,指示了冰期时冬季风更加强盛。  相似文献   

西菲律宾海780ka以来气候变化的岩石磁学记录:基于地磁场相对强度指示的年龄框架   总被引：2，自引：0，他引：2       下载免费PDF全文

葛淑兰  石学法  杨刚  吴永华 《第四纪研究》2007,27(6):1040-1052

文章对取自西菲律宾海本哈姆高原东部的两个钻孔岩芯进行了岩石磁学和古地磁研究,两个岩芯长度近4m,水深均超过5000m.在岩芯146底部出现了磁倾角倒转和相对磁偏角偏移,被认为是布容-松山极性转换(780ka);而岩芯89中没有发现磁倾角倒转和磁偏角偏移,表明其底部年龄比780ka年轻.岩石磁学结果表明沉积物的磁学特征符合磁性"均一性"条件:即主要载磁矿物为低矫顽力的磁铁矿,磁性矿物粒度在假单畴-单畴范围内,并且磁性矿物含量变化不超过10倍;据此构建了地磁场相对强度(RPI)的3个指标NRM/κ,NRM/ARM和NRM/SIRM.综合古地磁和地磁场相对强度与Sint800的对比结果,我们得到了两个岩芯的深度-年龄对比,在此基础上获得的岩石磁学记录表明,岩芯记录了Brunhes期以来的气候演化:冰期时,磁性矿物的粒度变粗,细粒磁性矿物含量降低;反之,间冰期时磁性矿物的粒度变细,细粒磁性矿物含量增加,与南海ODP1143孔记录的氧同位素具有一致的变化,这反映了间冰期时加强的化学风化对源区物质的影响而不是海面升降造成的沉积分选.而且,在间冰期时磁学参数反映的粒度大小亚峰谷值与氧同位素的亚峰谷值一一对应,表明间冰期沉积过程能反映气候的细微变化.这种磁学参数对气候的响应也出现在南海钻孔中,表明该特征至少是东亚海域沉积物的共同规律.对细粒磁性矿物比较敏感的ARM显示了与磁学粒度参数相似的变化,在间冰期为高值,冰期为低值,而对粗颗粒更敏感的κ和SIRM则缺乏这种与冰期-间冰期旋回的对应关系.与此同时,S-ratio变化不大并且缺乏与亚洲风尘记录的对应关系,表明自从780ka以来沉积区的低矫顽力磁性矿物一直是主要磁性载体,并且暗示物质来源应以来自陆地的悬浮体为主,而非风尘.研究区内自西向东降低的沉积速率表明了沉积物的主要来源是西部的吕宋岛和东亚大陆.400kaB.P.前后,磁学参数出现转折,粒度由逐渐变粗到稳定,磁性矿物含量降低以及变化幅度增加;同时,碳酸盐含量的变化也相应降低,反映了全球海区出现的碳酸盐溶解加剧即中布容事件.磁性矿物含量和粒度与冰期-间冰期的同步变化反证了地磁场相对强度指示年龄的正确性,同时岩石磁学参数对稳定氧同位素和碳酸盐含量的响应也揭示了岩石磁学方法是进行古气候和古海洋研究的有效工具.  相似文献   

10BE ISOTOPE RECORDS IN SEDIMENT CORE Z14-6 FROM THE EASTERN OKINAWA TROUGH DURING THE LAST DEGLACIATION AND HOLOCENE     

Yang Yongliang  Liu Zhenxia  Shen Chengde  Li Tiegang  Shi Xuefa  Cheng Zhenbo  Xiong Yingqian 《第四纪研究》2012,32(3)

文章讨论了末次冰期及全新世以来冲绳海槽中部偏东处的沉积物岩芯Z14-6中10Be的历史记录,并与冲绳海槽北部钻孔DGKS9603的10Be记录进行对比.重力柱状岩芯Z14-6取于冲绳海槽水下739m( 27°07'N,127°27′E),全长8.96m.选取了晚更新世末次冰期和全新世的层段(2～175cm,年代跨度为0.37 ～29.3kaB.P.)中12个层位,利用加速器质谱法测定了10Be的含量.Z14-6孔10Be的平均含量为6.10×108atoms/g,最高值(8.71×108atoms/g)出现在6.3kaB.P.层位,末次冰期10Be含量总体上处于低值.与DGKS9603孔(28°08.869′N,127°16.238′E;永深1100m,岩芯长585cm)的数据比较,Z14-6孔中10Be含量普遍较低.Z14-6孔的10Be沉积通量平均值为1.04×109 atoms/cm2 · ka.最高值(1.36× 109atoms/cm2·ka)出现在6.3kaB.P.层位,最低值(6.45×10s atoms/cm2·ka)出现在9.27kaB.P.层位.Z14-6孔所处水深较浅,黑潮流在末次冰期时并未流经Z14-6孔海区,所以其10Be沉积通量只相当于10Be的大气平均生产率( 1.21 ×109 atoms/cm2 ·ka).Z14-6孔中10Be沉积通量降低可能与几个低温事件有关,Z14-6孔在约3kaB.P.和9kaB.P.存在10Be通最减弱现象,因此推测黑潮产生较大变动.Z14-6孔在全新世一些时段的10Be沉积通量峰值显著高于末次冰期时的沉积通量峰值,表明当时黑潮对该海域已发生影响.  相似文献   

Mineralogical study of surface sediments in the western Arctic Ocean and their implications for material sources     

DONG Linsen  SHI Xuefa  LIU Yanguang  FANG Xisheng  CHEN Zhihua  WANG Chunjuan  ZOU Jianjun  HUANG Yuanhui 《极地研究(英文版)》2014,(3):192-203

Mineralogical analysis was performed on bulk sediments of 79 surface samples using X-ray diffraction. The analytical results, combined with data on ocean currents and the regional geological background, were used to investigate the mineral sources. Mineral assemblages in sediments and their distribution in the study area indicate that the material sources are complex. （1） Feldspar is abundant in the sediments of the middle Chukchi Sea near the Bering Strait, originating from sediments in the Anadyr River carried by the Anadyr Current. Sediments deposited on the western side of the Chukchi Sea are rich in feldspar. Compared with other areas, sediments in this region are rich in hornblende transported from volcanic and sedimentary rocks in Siberia by the Anadyr Stream and the Siberian Coastal Current. Sediments in the eastern Chukchi Sea are rich in quartz sourced from sediments of the Yukon and Kuskokwim rivers carried by the Alaska Coastal Current. Sediments in the northern Chukchi Sea are rich in quartz and carbonates from the Mackenzie River sediments. （2） Sediments of the southern and central Canada Basin contain little calcite and dolomite, mainly due to the small impact of the Beaufort Gyre carrying carbonates from the Canadian Arctic Islands. Compared with other areas, the mica content in the region is high, implying that the Laptev Sea is the main sediment source for the southern and central Canada Basin. In the other deep sea areas, calcite and dolomite levels are high caused by the input of large amounts of sediment carried by the Beaufort Gyre from the Canadian Arctic Islands （Banks and Victoria）. The Siberian Laptev Sea also provides small amounts of sediment for this region. Furthermore, the Atlantic mid-water contributes some fine-grained material to the entire deep western Arctic Ocean.  相似文献