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1.
海洋富有机碳岩石通常赋存对公众生命、人类健康和环境有潜在危害的痕量元素。与世界页岩平均值（ＷＳＡ）相比,中新世蒙特里建造（加利福尼亚最广泛的油源岩）富集多种痕量元素。早期研究表明,在这些岩石中,与有机碳呈高度正相关（γ２＞０．７５）的元素有铬（Ｃｒ）、铜（Ｃｕ）、镍（Ｎｉ）、锑（Ｓｂ）、硒（Ｓｅ）、铀（Ｕ）、钒（Ｖ）、锌（Ｚｎ）等,呈明显正相关（γ２＝０．４～０．７５）的元素有砷（Ａｓ）、钡（Ｂａ）、镉（Ｇｄ）、和钼（Ｍｏ）。在这１２种元素中Ｓｅ对环境最为有害,Ａｓ、Ｇｄ、Ｃｕ、Ｍｏ、Ｎｉ、Ｓｂ… 相似文献
2.
海水池塘施肥混养滤食性鱼贝的初步研究 总被引：1，自引：1，他引：0
实验于１９９５年７月１０日至９月１６日,在烟台市黄海水产集团公司第二养虾场进行。采用围隔生态系实验法,利用４个海水池塘陆基围隔（５ｍ×５ｍ）初步研究了台湾红罗非鱼（Ｏｒｅ－ｏｃｈｒｏｍｉｓｍｏｓｓａｍｂｉｃｕｓ×Ｏ．ｎｉｌｏｔｉｃｕｓ）与菲律宾蛤仔（Ｒｕｄｉｔａｐｅｓｐｈｉｌｉｐｐｉｎａｒｕｍ）施肥混养的效果。结果表明：菲律宾蛤仔的生产力为１．２４ｇ／ｍ２·ｄ,负荷力为３８３０．０ｋｇ／ｈｍ２;罗非鱼的生产力为１．８６ｇ·（ｍ２·ｄ）－１,负荷力为１５８０．８ｋｇ／ｈｍ２。鱼贝对施入氮、磷的利用率分别为１５．０６％和６．８０％,比单养罗非鱼要高;总生产力和总负荷力都明显高于单养罗非鱼。 相似文献
3.
海胆纲动物天然活性物质研究概况 总被引：1，自引：0，他引：1
对已从海胆纲动物中分离到的几种生物活性物质在分离提取及生理药理活性方面的研究情况做一概要介绍。１多聚不饱和脂肪酸１．１提取制备方法多聚不饱和脂肪酸（ＰｌｏｙｕｎｓａｔｕｒａｔｅｄＦａｔｔｙＡｃｉｄ,ＰＵＦＡ,又称ＨｉｇｈＰｏｌｙｕｎｓａｔｕｒａｔｅｄＦａｔｔｙＡｃｉｄ,ＨＰＵＦＡ）系指含有多个双键的长链脂肪酸,主要有二十碳五烯酸（ＥｉｃｏｓａｐｅｎｔａｅｎｏｉｃＡｃｉｄ,ＥＰＡ）、二十二碳六烯酸（Ｄｏ－ｃｏｓａｈｅｘａｅｎｏｉｃＡｃｉｄ,ＤＨＡ）和花生四烯酸（ＡｒａｃｈｉｄｏｎｉｃＡＣｉｄ,ＡＡ… 相似文献
4.
庙岛群岛的光棘球海胆主要分布于北四岛（南、北隍城岛,大、小钦岛）,砣矶岛及大、小竹山岛等,而南五岛极少分布。砣矶岛的海胆多是２～３年生壳径４～６ｃｍ的个体,海胆性腺成熟期为７月中旬至８月中旬,性腺发育与水温、栖息场和饵料等有关。海胆体重随季节而变化,繁殖季节体重Ｗ（ｇ）与壳径Ｄ（ｃｍ）相关,Ｗ＝２．５８２Ｄ２．０３４（ｒ＝０．８７）,性腺重ＧＷ（ｇ）与壳径Ｄ（ｃｍ）关系为ＧＷ＝０．０４０３Ｄ３．０８２８（ｒ＝０．８２７３）,壳径Ｄ（ｃｍ）与壳高Ｈ（ｃｍ）呈线性关系Ｈ＝０．５２２５Ｄ＋０．０６６８（ｒ＝０．９０７８）。壳径生长随年龄而变慢,２．８ｃｍ的幼海胆年增长２．１ｃｍ;６．１ｃｍ的成海胆年增长０．４３ｃｍ。光棘球海胆嗜食海带和裙带菜,平均日摄食量６．０ｃｍ的海胆为２．６ｇ,４．０ｃｍ的为１．３４ｇ,３．１ｃｍ的为１．３ｇ,幼海胆摄食率较高的原因是因其生长发育快速,活动强度和代谢水平高。 相似文献
5.
《海洋学报(英文版)》1996,15(1):54-58
ＡＰＰＥＮＤＬＸＡＩｎｅｒｔｉａｌｓｔａｂｉｌｉｔｙａｎａｌｙｓｉｓＧＯＶＥＲＮＩＮＧＥＱＵＡＴＩＯＮＳＡＮＤＡＮＡＬＹＴＩＣＡＬＳＯＬＵＴＩＯＮＴｏｆｏｃｕｓｏｎｆｉｎｉｔｅｄｉｆｆｅｒｅｎｃｅｓｃｈｅｍｅｓｏｆｔｈｅＣｏｒｉｏｌｉｓｔｅｒｍｓ，ｗ... 相似文献
6.
宁波及其邻近海域沉积物释放耗氧有机物（COD）的初步研究 总被引：2，自引：0，他引：2
本文通过对城市污水纳污海区沉积物样品释放有机物的研究，初步揭示了沉积物释放耗氧有机物（ＣＯＤ）的一般规律。研究表明宁波海域沉积物释放ＣＯＤ的范围在０．１５×１０－３～０．８０×１０－３之间，释放速率平均为１０３．９ｍｇ／（ｍ２．ｄ）；舟山沈家门附近海域沉积物释放ＣＯＤ速率平均为２５３．１ｍｇ（ｍ２·ｄ）。沉积物释放ＣＯＤ的量与沉积物中有机质的含量成正比，而其释放速率与沉积物有机质的含量关系不大。 相似文献
7.
栉孔扇贝血淋巴中超氧化物歧化酶和过氧化氨酶活性及其性质的研究 总被引：2，自引：0，他引：2
于１９９７年１０月－１９９８年１月,从胶州湾贝类养殖场购买栉孔扇贝,分别采用邻苯三酚自氧化法和过氧化氢法测定了其血细胞和血清中的超氧化物歧化酶（ＳＯＤ）和过氧化氢酶（ＣＡＴ）的活力,并对ＳＯＤ类型的鉴别区分、ＳＯＤ和ＣＡＴ的热稳定性以及温度对ＳＯＤ和ＣＡＴ活力的影响进行研究。结果表明,血细胞中ＳＯＤ和 ＣＡＴ活力分别为３１２．７Ｕ和 １２４．４Ｕ,血清中ＳＯＤ和ＣＡＴ活力分别为１０２．３Ｕ和７３．８Ｕ;冻存１０ｄ后,血清中ＳＯＤ的活力丧失２４．６％,而ＣＡＴ的活力丧失４０．８％;血细胞中ＣｕＺｎ－ＳＯＤ和Ｍｎ－ＳＯＤ的活力分别为１９３．４Ｕ和８２．３Ｕ,血清中仅存在ＣｕＺｎ－ＳＯＤ活性;血清中ＳＯＤ的热稳定性很高,在８０℃下保温３０ｍｉｎ后,酶活力仍很高,而ＣＡＴ的热稳定性较低;血清中的ＳＯＤ和ＣＡＴ的最适温度分别为５０℃和４５℃。 相似文献
8.
ＡｎＡＤＩｔｅｃｈｎｉｑｕｅｆｏｒｓｏｌｖｉｎｇｔｈｒｅｅ－ｄｉｍｅｎｓｉｏｎａｌｃｏａｓｔａｌｃｉｒｃｕｌａｔｉｏｎＹａｎｇＬｉａｎｗｕ１，＊ａｎｄＪｏｓｅＯｚｅｒ２（ＲｅｃｅｉｖｅｄＮｏｖｅｍｂｅｒ２７，１９９６；ａｃｃｅｐｔｅｄＤｅｃｅｍｂｅｒ... 相似文献
9.
螺旋藻多糖对CD3AK细胞增殖能力的影响 总被引：7，自引：0，他引：7
研究了螺旋藻多糖（ＰＳ）对ＣＤ３ＭｃＡｂ激活的杀伤细胞（ＣＤ３ＭｃＡｂ Ａｃｔｉｖａｔｅｄ Ｋｉｌｌｅｒ Ｃｅｌｌｓ,ＣＤ３ＡＫ Ｃｅｌｌｓ）增殖能力的影响。结果表明,当ＰＳ浓度为２．５μｇ·ｍｌ＾－１培养体系条件下,对ＣＤ３ＡＫ细胞具有明显的刺激细胞增殖作用（Ｐ〈０．０２）;对培养长达２３ｄ的ＣＤ３ＡＫ细胞杀伤肿瘤细胞（Ｋ５６２细胞）的活性仍维持在较高的水平（４６．５％￣５０％）。提示ＰＳ对辐射 相似文献
10.
实验研究了一个中型水库（黄同水库）中几种主要微量营养元素（Ｆｅ、Ｍｎ、Ｚｎ、Ｃｕ、Ｍｏ）的存在形态、分布及其季节变动。主要结果为：（１）水库中Ｆｅ、Ｍｎ、Ｚｎ和Ｃｕ的平均总浓度分别为３６４．３、１１２．１、９６．０１和３．２４μｇ／Ｌ;Ｍｏ的溶解态平均浓度为３．２６μｇ／Ｌ。Ｆｅ和Ｍｎ以颗粒态为其主要存在形式,而Ｚｎ和Ｃｕ则以溶解态为主。（２）该水库５种微量元素的水平分布呈均匀化特征,但其浓度具有较明显的季节性变化。其垂直分布互有差异,Ｆｅ、Ｍｎ、Ｚｎ随水层深度增加而递减,而Ｃｕ和Ｍｏ的垂直变化甚小。（３）微量元素存在形态与水化学因子存在一定相关性,ＰＦｅ、ＰＺｎ、ＰＣｕ与ＤＯ间具有良好负相关,而ＤＺｎ、ＤＣｕ、ＤＭｏ和ＰＺｎ、ＰＦｅ与叶绿素间均呈紧密正相关。 相似文献
11.
南海铁锰结核(壳)的元素地球化学研究 总被引：1，自引：0，他引：1
本文利用南海11个铁锰结核(壳)样品的化学分析资料,研究了铁锰结核(壳)中Fe,Mn,Cu,Co,Ni,Pb,Zn,Cr,K,Na,Ca,Mg,Si,P,Al,Ti,Sr,Ba及∑REE的元素地球化学特征。结果表明:(1)铁锰结核(壳)以高Fe,∑REE,低Mn,Cu,Co,Ni等元素为主要特征;(2)铁锰结核(壳)中Fe,Mn间无明显相关,而Fe与∑REE,∑Ce,∑Y呈弱的正相关,Mn与∑REE,∑Ce,∑Y呈明显的正相关,结壳中Fe,Mn与Si,Al,Cu Co Ni呈负相关;(3)结核(壳)中Mn/Fe与Cu/Ni,Ce/La呈负相关,Mn/Fe主要受Mn控制;(4)结核(壳)中Fe,∑REE等元素主要来自南海陆源中酸性岩类的风化、淋滤和沉积。 相似文献
12.
冲绳海槽北端表层沉积物过渡元素地球化学特征 总被引：4，自引：0，他引：4
利用原子吸收和等离子发射光谱等方法,对冲绳海槽北端184个表层沉积物中的Al和过渡元素(Ti、Cr、Mn、Fe、Co、Ni、Cu、Zn和Zr)进行了化学分析。结果表明,由于受生源碎屑稀释作用的影响,过渡元素在陆架砂质区含量较低,其分布呈北西-南东向舌状延伸;由于细粒组分的增加,在陆架细粒沉积区和海槽区过渡元素含量较高。Mn主要在海槽区富集,在陆架和陆坡区变化不大。除了Mn之外,Al和其他过渡元素均呈明显正相关。Al/Ti比值与陆壳平均值接近,说明二者主要来源于陆源碎屑。Mn/Fe比值与邻近海区沉积物类似,但在陆架区CaO含量大于20%的沉积物和海槽区沉积物中相对较高,这分别是生物富集作用和自生沉积的结果。过渡元素富集因子分析结果表明,研究区过渡元素部分来自于黄河、部分来自于长江物质。 相似文献
13.
Shizuko Hirata 《Marine Chemistry》1985,16(1):23-46
Phosphorus and metals bound to organic matter were separated from coastal sediments of Harima Sound in Seto Inland Sea, Japan by extraction with NaOH and fractionated by Sephadex G-25 chromatography. Phosphorus and metals were determined in the eluates by a multi-channel, inductively coupled plasma-atomic emission spectrometer. Phosphorus and Cu, Zn, Fe, Mn, Ni, Cr, Co and Ti bound to organic matter with high molecular weights (OMHMW) (MW ? 5000) were found to be present in the sediments, but no Mo or V were found. The technique provides minimum estimates of the amounts of P and metals bound to organic matter. These organic complexes show surface enrichment in a sediment core (0–20 cm) and their contents decrease with depth. Also, the amounts of eighteen elements, namely: P, Fe, Mn, Zn, Cu, Si, Al, Ti, Pb, Co, Ni, Cr, Mo, V, Na, K, Ca and Mg, in H2O, ammonium acetate at pH 7 and 5, hydrogen peroxide, hydroxylamine hydrochloride and hydrogen fluoric acid soluble fractions have been determined with a selective chemical leaching technique for the 210Pb-dated sediment core sample. Considerable amounts of P (6–19%) and Cu (5–21%) were associated with organic matter, in contrast to other metals such as Fe, Mn, Zn, Ni, Cr, Co and Ti which were associated with sulfide and silicate. 相似文献
14.
Fourteen trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn) were analyzed in livers and muscles from 22 fish species from the New Caledonia lagoon, which is subjected to important chemical inputs due to intense land-based mining activities (New Caledonia is the third largest world producer of Ni). The results of this baseline research indicated that livers generally concentrated trace elements to a greater extent than muscles. Nevertheless, the overall trace element concentrations in both tissues were barely above the levels reported in fish and thus contamination at the local scale was poorly discriminated. Although these levels were low, preliminary risk assessment from a global health standpoint suggests that As would be an element potentially leading to exposure of concern for fish consumers. Based on the trace element concentrations in livers and the fish trophic preferences, some trends have been observed among trophic groups: Ag, Cu, Fe, Hg, and Zn concentrations were generally higher in liver of fish with the highest trophic position whereas Cd concentrations were lower in these groups. The use of the leopard coral grouper Plectropomus leopardus as a resident top predator allowed determining the geographical variations in contamination levels with significant differences for six out of the fourteen elements investigated. The sampling sites influenced by anthropogenic inputs were revealed by high Ag, Cd, Cu, Hg, and Pb concentrations. Such geographic differences also applied to Zn but surprisingly not for the typical elements associated with Ni mining, i.e., Co, Cr, Mn and Ni. 相似文献
15.
Abstract A large number of surface sediments as well as short sediment cores collected in the Central Indian Ocean Basin have been subjected to various geochemical investigations during the last one and half decade. The studies varied, covering different aspects of sediments and resulting in a number of publications. In the present article, we have put together the data from 82 surface sediments and 14 short sediment cores, including 25 new analyses, to study the trend of their distribution and source at large. The distribution maps of elements show that highest concentrations of Mn, Cu, Ni, Zn, Co, and biogenic opal in the surface sediment occurs between 10°S and 16°S latitude, where diagenetic ferromanganese nodules rich in Mn, Cu, Ni, and Zn are present. The studies highlight that the excess element concentration (detrital unsupported) such as Mn, Cu, Ba, Ni, Co, Pb, and Zn have contributed >80% of their respective bulk composition. These excess elements exhibit strong positive correlation with each other suggesting their association with a single authigenic phase such as Mn oxide. Biogenic opal contributes 30–50% of the total silica in the siliceous sediment. Aluminum, Fe, and K have contributed >60% from terrigenous detrital source compared to their bulk composition. In calcareous ooze, Ca, and Sr excess contribute >95% while, in siliceous ooze it is only 50% of their bulk composition. Nearly 35% of structurally unsupported Al in the sediment raises doubt of using Al as a terrigenous index element to normalize the trace and minor elements. Biogenic apatite is evident by the positive correlation between Ca (<1%) and P. Calcium, Sr, and P depict a common source such as biogenic. Bulk element concentration such as Li, V, Cr, Sc, and Zr are positively correlated with Ti indicating their terrigenous detrital source. Rare earth element (REE) concentration increases from calcareous ooze to siliceous ooze and reaches a maximum in the red clay. Presence of positive Eu-anomaly in these sediments has been attributed to aeolian input. REE in these sediments are mostly carried by authigenic phases such as manganese oxide and biogenic apatite. Based on the distribution of transition elements in the sediment cores, three distinct zones—oxic at top, suboxic at intermediate depth, and a subsurface maxima—have been identified. Oxic and suboxic zones are incidentally associated with high and low micronodule abundance in the coarse fraction (>63 μm) respectively. Ash layers encountered at intermediate depth between 10 to 35 cm are correlative with the Youngest Toba eruption of ～74ka from Northern Sumatra. This ash is mainly responsible for the high bulk Al/Ti ratio up to 48.5 (three times higher than Post Archean Australian Shale), other than scavenging of dissolved Al by biogenic components. 相似文献
16.
以成矿作用反应场中的成矿物质和成矿环境为切入点,指出洋底水-沉积物界面附近形成了金属垒、碱性垒和氧化垒的垒群带以及矿物的沉析带;溶解态成矿金属的存在形式除Fe主要呈高价态外,Mn、Cu、Ni、Co均呈低价态;洋底沉析的矿物有赤铁矿、针铁矿、石英、硅酸盐类和碳酸盐类矿物。成矿溶液中存在富含Mn、Fe的胶体和微粒,其Mn、Fe含量比溶解态的高出百倍至千倍,Cu、Ni、Co含量也以增高为主。南极底层流的供氧使表层沉积物均呈浅黄、黄褐、褐色系列色调,并且成矿溶液呈低温、弱碱性、强氧化环境。在构筑成矿金属运聚和分异的动态模型基础上,提出了氧化、胶体化学和生物化学是结核生成的作用链,归纳为以洋底垒群带和矿物沉析带的复合带为背景、胶体化学作用为主导、物理化学作用和生物化学作用叠加的外生成因水下沉析的结核成矿模式。 相似文献
17.
东海陆架晚第四纪沉积物化学成分及物源示踪 总被引：11，自引：0，他引：11
东海陆架EA1孔和EA5孔沉积物化学成分变化范围较大。与东海陆架表层沉积物相比，钻孔沉积物的Si,Al,Mg,Mn,Ti,P,Ba,Zr,Co,Ni,Cu,Zn,Cr明显偏高，而Fe,Na,Ca,Sr,Li,U明显偏低，与全球大陆地壳化学组成相比，钻孔沉积物的Si,Li,Rb,Ba,Th,Zr,Hf,Cu,Zn,Pb偏高，而Al,Na,Ca,Mg,Fe,Mn,Ti,P,Sr,U,Co,Ni,V,Cr偏低，钻孔沉积物的化学成分在垂向上具有明显变化，主要受岩性和沉积环境的控制，钻孔沉积物中元素的富集因子（EF）均小于10，接近于1，表明钻孔沉积物主要来自大陆地壳，一些元素因分异或外来物质加入而富集，一些元素则因分异带出而亏损，钻孔沉积物源区的DF值判别表明，钻孔沉积物与现代黄河，长江沉积物均有亲缘关系，可能是在末次冰期最盛期，由于气候带南移，干旱区域扩大，在古长江搬运沉积物中类似现今黄河沉积物的干旱组分明显增加，从而导致了地球化学示踪结果的长江与黄河双重性，或者说古气候的变化导致了古长江搬运物质成分的变化。 相似文献
18.
《Deep Sea Research Part I: Oceanographic Research Papers》1999,46(1):149-169
Particulate fluxes of trace elements (Al, Cd, Co, Cu, Fe, Mn, Ni, P, Ti, V and Zn) in the northeast Atlantic Ocean (three positions at latitudes from 33°N to 54°N along ∼20°W) were measured using time-series sediment traps between March 1992 and September 1994. Significant variabilities of fluxes with season and depth (1000 m to maximum of 4000 m) were observed only for ‘biogenic elements’, such as Cd, Ni, Zn or P. On the other hand, we found a distinct large-scale increase of fluxes into the deep-sea traps to the south for Al, Co, Fe, Mn and V. We attribute this latitudinal gradient to the increasing influence of the Saharan dust plume. The biogenic flux decreased towards the south. This trend was clearly visible for Cd and P only. The fluxes of other ‘nutrient-like’ elements, such as Ni or Zn, exhibited a general decrease between 53°N and 33°N. We compared our sedimentation flux data with published data from the western North Atlantic basins. For this purpose we corrected the deep-sea fluxes of Cu, Mn, Ni and Zn for their lithogenic fractions on the basis of Al, with average crustal material and granitic rocks as references. The comparison indicates that these ‘excess’ fluxes are a factor of at least 2 higher in the western basins for the selected elements. Estimated fluxes are in good agreement with reported atmospheric deposition in the two areas. The noted imbalance between the non-lithogenic atmospheric input of Mn and the determined ‘excess flux’ in the deep northeast Atlantic indicates an additional input in the form of a lateral flux of dissolved Mn(II) species and scavenging onto sinking particles. With respect to the mechanism of sedimentation, a unique behaviour is noticed for the refractory elements Co, Fe, Mn, Ti and V, which were found to correlate with the vertical transport of Al (clay). The ‘excess’ fluxes of Cu, Ni and Zn are linearly related to Corg, whereas the overall relation of Cd to P fluxes exhibits a molar Cd/P ratio of 2.0×10-4, which is close to the ratio in the dissolved fractions in the northeast Atlantic. 相似文献
19.
Elemental mass-balance of material carried by major world rivers 总被引：3，自引：0，他引：3
An estimate of average river particulate matter (RPM) composition was bàsed on analyses of more than 40 elements in the Amazon, Congo, Ganges, Magdalena, Mekong, Parana and Orinoco rivers, to which were added literature data for 13 other major world rivers, covering the whole spectrum of morphoclimatic features. Geographic variations of major elements in RPM are mostly linked to weathering types and to the balance between weathering rate and river transport. As a result of chemical erosion, Al, Fe and Ti are enriched in RPM with respect to the average parent rock, while Na, Ca, Mg and Sr are strongly depleted. These figures are directly related to the relative importance of dissolved and particulate transport in rivers; this has been computed for each of 40 elements. In order to study weathering on a global scale, the total observed elemental fluxes (dissolved + particulate) have been computed and compared to theoretical ones. The latter were derived from the elemental content in the average parent rock and the total quantity of weathered material, computed from the Al ratio in RPM and in parent rock. Observed and theoretical fluxes are balanced for the less mobilized elements (rare earths, Co, Cr, Cs, Fe, Mn, Rb, Si, Th, Ti, U and V) for which no enrichment relative to Al is noted in RPM, and for B, Ba, Ca, K, Mg, Na, Sr which are relatively depleted in RPM due to their high dissolved transport. Additional fluxes have been found for Br, Sb, Pb, Cu, Mo, Zn and are possible also for Ni and P. This is reflected by marked enrichments in RPM relative to Al for the poorly or moderately dissolved transports (Pb, Cu, Zn). Several hypotheses involving either the natural origin (volcanic dust, marine aerosols, geochemical fractionation) or the artificial origin (worldwide pollution) are discussed to explain these discrepancies, assuming river transport and weathering either to be in a steady state on a global scale or not. However, none of them can fully account for these additional fluxes. It is most likely that these excesses have multiple origins, anthropogenic or natural or both. The comparison between RPM and deep-sea clay compositions emphasizes the prime influence of river input on oceanic sedimentation of Si, Al, Fe, Ti, lanthanides, Sc, Rb, V, etc. A few elements such as Zn, Sb, occur in excess in RPM as compared to deep-sea clays; in order to balance this excess, a remobilization of these elements out of the sediment can be considered. Finally, the enrichment of Co, Cu, Mn and Ni in deep-sea clays compared to RPM is discussed and attributed to several sources and processes. 相似文献
20.
The early diagenesis of trace elements (V, Cr, Co, Cu, Zn, As, Cd, Ba, U) in anoxic sediments of the Achterwasser, a shallow lagoon in the non-tidal Oder estuary in the Baltic Sea, was investigated in the context of pyrite formation. The dissolved major redox parameters show a two-tier distribution with transient signals in the occasionally re-suspended fluid mud layer (FM) and a permanently established diagenetic sequence in the sediment below. Intense microbial respiration leads to rapid depletion of O2 within the uppermost mm of the FM. The reduction zones of Mn, Fe and sulfate overlap in the FM and in the permanently anoxic sediment section which appears to be a typical feature of estuarine sediments, under low-sulfate conditions. Degrees of pyritization (DOP) range from 50% in the FM to remarkably high values > 90% at 50 cm depth. Pyrite formation at the sediment surface is attributed to the reaction of Fe-monosulfides with intermediate sulfur species via the polysulfide pathway. By contrast, intense pyritization in the permanently anoxic sediment below is attributed to mineral growth via adsorption of aqueous Fe-sulfide complexes onto pyrite crystals which had originally formed in the surface layer.The studied trace elements show differential behavior patterns which are closely coupled to the diagenetic processes described above: (i) Zn, Cu and Cd are liberated from organic matter in the thin oxic layer of the sediment and diffuse both upwards across the sediment/water boundary and downwards to be trapped as monosulfides, (ii) V, Cr, Co and As are released during reductive dissolution of Mn- and Fe-oxyhydroxides, (iii) U removal from pore water occurs concomitantly to Fe reduction in the FM and is attributed to reduction of U(VI) to U(IV), (iv) the Ba distribution is controlled by reductive dissolution of authigenic barite in the sulfate reduction zone coupled with upward diffusion and re-precipitation. The incorporation of trace elements into pyrite is most intense for Co, Mn and As, intermediate for Cu and Cr and little to negligible for U, Zn, Cd, V and Ba. The observed trend is largely in agreement with previous studies and may be explained with differing rates for ligand exchange. Slow and fast ligand exchange and thus precipitation kinetics are also displayed by downcore increasing (Mn, Cr, Co and As) or constantly low (Zn, Cu, Cd) pore water concentrations. The downward increasing degrees of trace metal pyritization (DTMP) for Co, Cu, Zn and As are, in analogy to pyrite growth, assigned to adsorption of sulfide complexes or As oxyanions onto preexisting pyrite minerals. 相似文献