塔里木盆地下寒武统底部富有机质层段地球化学特征及成因探讨

塔里木盆地下寒武统底部玉尔吐斯组富有机质沉积层段分布广泛, 层位稳定, 其中的硅质岩发育, 并伴有磷矿产出. 硅质岩的Al/(Al + Fe + Mn)和Si/(Si + Al + Fe)比值分别在0.0023 ~ 0.0046和0.965 ~ 0.98之间, 表明其形成于海底热水沉积环境, 且远离陆源区. 富有机质沉积层段明显富集As, Hg, Pb, Zn, Cu, Co, P, V, Ba等微量元素, Ba/Sr比值分布在21.2 ~ 158.1之间, 与现代海底热水沉积物中的Ba/Sr比值相似, 具有明显的海底热水沉积特征; 硅质岩的稀土元素总量SREE从8.81 ~ 56.682 mg/g, 平均值为31.414 mg/g, 介于大陆边缘硅质岩与深海硅质岩稀土总量之间; 硅质岩的LREE/HREE比值为1.01 ~ 3.56, 显示出海底热水沉积的特征. 该组中有机质丰度(TOC)与表征海底热水活动的地球化学参数Ba/Sr值等具有正相关趋势, 这表明海底热水活动对有机质的富集有明显的影响.     

河西走廊花海古湖泊全新世白云石的发现及其环境意义

通过对河西走廊花海古湖泊沉积物的X衍射分析发现,全新世期间有明显的白云石沉积.岩性、沉积过程、石膏以及Fe3+含量的变化表明,花海湖全新世白云石沉积环境以还原环境为主,即还原环境利于白云石的形成,为白云石的成因研究提供了新的证据.白云石作为碳酸盐矿物,可以反映湖水盐度,但并非直接指示了湖水的咸化.随着湖水盐度的进一步增加,在硫酸盐型湖泊中,白云石含量随盐度的增加而相应减少,表明利用白云石分析湖水盐度时需要结合其他矿物进行分析.结合石膏含量的变化,花海湖全新世时期白云石含量的变化可以揭示该区域湖水盐度的变化.在10.478.87 cal ka B.P.早全新世时期,湖水的盐度较高,气候由干向湿转变;8.87 cal ka B.P.时期,有大量石膏沉积,显示了湖水盐度的进一步升高,气候干旱;随后湖水相对淡化,气候湿润;5.50 cal ka B.P.至今,沉积出现间断,气候逐渐干旱.     

台湾大鬼湖的古气候研究

台湾大鬼湖之黑色沉积物岩芯中出现特殊的白层,其性质与黑色沉积物差异很大:白层有较低的孔隙率、有机质含量、碳/氮比,与较高的碳/硫比和氮/硫比,有机质较偏向水中浮游生物,可能是较干冷的气候下沉积的;而黑层之有机质主要来自陆生植物,可能代表较湿暖的气候.主要的白层出现年代,如0aAD,500aAD,700aAD,900aAD,1350aAD和1500aAD等,大多可以和中国或秘鲁冰芯所记录之干冷期及高尘暴期相对应,似乎表现大尺度的气候变动。     

流域数据模型研究—以太湖流域西苕溪流域为例

对江汉平原江陵剖面沉积物中的总有机碳（TOC）、总氮（TN）、有机碳同位素δ13C值和粒度参数的分布特征与环境气候的关系进行了研究.结果表明：沉积物中有机碳、总氮较高,有机质的δ13C值偏负,沉积物的平均粒径较粗时,气候温暖湿润;反之,沉积物中有机碳、总氮较低,有机质的δ13C值偏正,沉积物的平均粒径较细时,气候温凉偏干.结合14C测年,判别江汉平原江陵地区的古气候演化过程：8900-6070 aBP,为温湿时期;6000-4600 aBP为相对冷干时期;4600-2500 aBP为温暖湿润时期;2500 aBP以来为温凉偏干时期.     

艾比湖水化学演化的初步研究

本文通过野外地质调查和大量样品的分析测试结果,从以下三个方面对艾比湖湖水的水化学特征进行论述:(1)湖水的矿化度和pH;(2)湖水的化学组成;(3)湖水化学组分的侧向分布。初步揭示了湖水水化学变化和主要化学元素迁移和富集的规律。艾比湖沉积物中碳酸盐矿物组成及其地球化学性质反映湖水化学组成的变动。这种变动明显受气候环境变化的影响。因此,CK4孔和湖底沉积物中的碳酸盐沉积,提供了许多信息作为湖水化学演化和古气候波动的标志,根据其碳酸盐含量、方解石含量、方解石格架中MgCO_3mol.％、Sr含量和Sr×1000/Ca比值,最后结合碳酸盐的沉积特征、地球化学演化和古沙嘴的演变,进一步阐明了湖水化学演化的趋势。     

泥炭沼泽不同植物群落中地表糙度变化及其影响机制

对藏南沉错CCl孔216个沉积物样品进行了15种金属元素含量的测试,研究金属元素含量的分布特征,以及与粒度参数的变化关系．结果显示：金属元素的分布特征可分为三组,K、Na、Mg、Al、Ti、Ba、Cu、Zn、Fe、Pb、Cr、V等12种元素具有较为相似的变化趋势;Ca和Sr变化趋势相同;而Mn与其他任何一种元素都不相似．元素分布与粒度参数的相关分析结果表明,Ca、Ti、Pb的变化与沉积物粒度没有明显的关系;K、Na、Al、Ba、Cu、Fe、Cr、V等8种元素与沉积物粘土含量（〈4um）呈正相关关系;Mg、Zn、Mn与粉砂含量（4—63μm）呈正相关关系;而Sr与砂含量（〉63gm）呈正相关关系本研究中大部分元素的粒度效应与其他湖泊、海洋等水体沉积物中元素的粒度效应具有一致的结果．与本岩芯已有的过去1400年来的环境重建资料对比可以发现,在不同的环境变化阶段,元素组合特征都与湖区环境状况具有较好的对应性．其中大部分元素的含量变化受物源条件即流域风化侵蚀程度的影响,而Ca含量不受沉积物粒度变化影响,且与沉积物中碳酸盐含量、Sr／Ba具有很好的相关性,说明其变化受物源条件影响小,而主要与湖水理化性质、蒸发强度以及湖泊沉积过程有关．     

太平洋富钴结壳高密度环境记录解读

生长缓慢、具有层带结构的海山富钴结壳蕴含着高信息密度的古海洋环境变化记录．具有微米级空间分辨率的现代微探针技术可解读结壳中的环境信息．采用具有微米级空间分辨率和ng／g级检出限的激光剥蚀电感耦合等离子体质谱与电子探针相结合,测定了采自中、西太平洋海山区4个典型板状结壳样品剖面中包括全部稀土在内的40多个元素的微区分布,获得了结壳生长期这些元素的分布及其相互关系变化的特征曲线;采用^10Be法和经验公式法相结合,对结壳整个生长期进行了生长速率计算和定年．重点讨论了A1／（Fe＋Mn）及P和Y／Ho记录的古海洋环境和古气候意义,认为Al／（Fe＋Mn）记录可反映亚洲季风气候的演化历史;通过将P和Y／Ho记录与深海沉积物的碳同位素记录进行对比,认为它们是生物成因事件的指示剂．最后对结壳定年及现代微探针技术的方法学问题进行了讨论．     

固城湖晚全新世以来的孢粉组合及环境变迁

本文依据固城湖GD钻孔系统的孢粉分析资料,将井深6.3m岩心所做的孢粉图式,结合~(14)C测年,从下面上分为8个孢粉组合带,进而论述了4000年来该区的植被发展和气候的4次冷暖交替的变化。4次冷期约为3.0—2.5KaB.P.2.0—1.5KaB.P.、1.0—0.8KaB.P.和0.4Ka以来。此外,还根据沉积物中的硅藻分析、有机质δ~(13)C值、有机碳含量及历史记载等资料,侧重讨论了气候及人类活动对湖泊环境演变的影响。     

梵净山九龙池沉积物氮同位素组成与全新世气候演变过程

湖泊沉积物氮同位素(δ¹⁵N)在古环境、古气候变化方面有着指示气候干湿变化的重要作用,但目前学界对于δ¹⁵N记录作为气候代用指标所指示的气候干湿变化特征仍缺乏深入探索。本文以贵州省梵净山九龙池湖泊沉积物为研究对象,分析并探讨δ¹⁵N所记录的梵净山地区气候干湿变化过程与特征,并结合总有机碳(TOC)、总氮(TN)和碳氮比值(C/N)数据进行对比研究,结果表明:(1)由于九龙池湖泊沉积物有机质受流域输入影响,气候湿润时,陆生植物增多,土壤湿度增大,外源输入对湖泊沉积物有机质影响增大,沉积物δ¹⁵N值偏负;气候干旱时,陆生植物减少,土壤湿度降低,外源输入对湖泊沉积物有机质影响减小,沉积物δ¹⁵N值偏正;(2)九龙池湖泊沉积物δ¹⁵N记录很好地揭示了梵净山地区全新世的气候干湿变化过程,即早期(11.5—9.2 ka B.P.)亚洲夏季风增强,气候从干旱期向湿润期转变,中期(9.2—3.0 ka B.P.)亚洲夏季风强盛,气候整体处于湿润期,晚期(3.0—2.2 k...     

太湖草源性"湖泛"水域沉积物营养盐释放估算

于太湖草源性"湖泛"暴发期,采集柱状沉积物并应用peeper被动采样装置获得"湖泛"区原位沉积物间隙水.泥水样品分析表明:"湖泛"发生水域表层(0~7 cm)沉积物的含水率、孔隙度和有机质含量均明显高于对照区,其中有机质含量更是对照区样品的4倍左右,沉水植物残体促使表层沉积物物化性质改变的作用明显;"湖泛"发生水域表层沉积物间隙水中铵态氮(NH+4-N)、溶解性反应磷(SRP)及Fe2+含量远高于未发生区,植物残体降解对沉积物厌氧环境的营造显著.运用分子扩散模型对沉积物释放通量估算:"湖泛"发生区沉积物NH+4-N、SRP和Fe2+的释放速率分别是对照区的49.8、15.3和123.1倍.研究认为,草源性"湖泛"水体氮、磷等营养物含量升高的主要原因是沉积物的释放,而"湖泛"所营造的厌氧环境是氮、磷释放急剧增加的主要驱动因素.     

The chemistry of hydrothermal mounds near the Galapagos Rift

Samples dredged from the sediment mounds have a unique chemistry and mineralogy which reveals details of the hydrothermal processes that produce these deposits. The mounds form primarily by deposition of Fe, Mn and Si from hydrothermal fluids which circulate through the basalt crust and the overlying sediments. The Mn, Fe and Si are strongly fractionated in the process; the Fe and Si precipitate within the mounds under slightly reducing conditions as nontronite, while the Mn is deposited as Mn oxyhydroxides at the seawater-sediment interface. The nontronite is exceptionally well crystallized, and contains less than 200 ppm Al. The Mn minerals, todorokite and birnessite, also have exceptional crystallinity and the distribution of trace elements Cu, Ni, Zn, Co, Ca and Ba in these phases agrees with predictions made on the basis of models of their crystal structure. The environment of deposition which produces this suite of minerals — slow percolation of hydrothermal fluids through pelagic sediments — may not be unique to the Galapagos Rift, as the same suite of minerals has been found in similar setting in the Gulf of Aden and on the Mid-Atlantic Ridge.     

Dynamics of dissolved major (Na,K, Ca,Mg, and Si) and trace (Al,Fe, Mn,Zn, Cu,and Cr) elements along the lower Orinoco River

This study addresses the changes in dissolved major and trace element concentrations along the Orinoco River, including the mixing zone between the Orinoco and Apure Rivers. Water samples from the Apure and Orinoco Rivers were collected monthly in four sectors over a period of 15 months. Auxiliary parameters (pH, dissolved oxygen, conductivity, and temperature), total suspended sediments, dissolved organic carbon (DOC), and major (Na, K, Ca, Mg, and Si) and trace (Al, Fe, Mn, Zn, Cu, and Cr) element concentrations were measured in all sectors. The relative contribution of both rivers after the Apure–Orinoco confluence was determined using Ca as a tracer. Moreover, a mixing model was developed to determine whether dissolved species exhibit a conservative behavior during mixing. The results indicate that DOC is removed from waters during the Apure–Orinoco mixing, probably due to absorption of DOC on mineral phases supplied by the Apure River. Dissolved Na, Ca, and Mg behave conservatively during the mixing processes, and their concentrations are controlled by a dilution process. The anomaly in the temporal pattern of K in the Orinoco is caused by the input of biogenic K originating from the Apure River during the high‐water stage. The loss of dissolved Si during the low‐water stage can be explained by the uptake of Si by diatoms. Dissolved Mn, Zn, Al, and Fe showed a non‐conservative behavior during the Apure–Orinoco mixing. The removal of Mn and Zn from the dissolved phase can be explained by the formation of Mn‐oxyhydroxides and the scavenging of Zn onto Mn oxides. Dissolved Fe is controlled by redox processes, although the removals of Fe and Al due to the preferential adsorption of large organometallic complexes by mineral surfaces after the Apure–Orinoco confluence can affect the mobility of both elements during transport. The conservative behavior shown by Cu and Cr can be related to the tendency of both elements to be complexed with small organic colloids, which are not preferentially adsorbed by clays.     

Evaluation of metal contamination in coastal sediments of the Bay of Bengal, India: geochemical and statistical approaches

Surface sediment samples collected from the inner shelf region of the Bay of Bengal, were analysed for the major elements and total and acetic acid available trace elements (Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Si, Zn) to evaluate geochemical processes influencing their distribution. Major elemental analysis showed that the sediments had high concentrations of Si and relatively low concentrations of Al and Fe. Both major elemental and trace metal concentrations indicated that the sediments represent weathered products of granite and charnockite. Normalization of metals to Al indicated relatively high enrichment factors for Pb, Cd, Zn and Cr. The higher proportions of nondetrital Pb (66%), Cd (41%) and Co (28%) reveal metal contamination due to anthropogenic inputs. Factor analysis (FA) identified six possible types of sedimentological and geochemical associations. The dominant factor accounting for 26.9% of the total variance identifies an anthropogenic input and accumulation of nondetrital Cd, Co, Cr, Ni and Pb. Association of these metals with CaCO3 reveals that shell fragments in the surface sediments are likely act as a carrier phase for nondetrital metals. The results are discussed in the context of the sources and pathways of elements in the Bay of Bengal.     

The Apure River: geochemistry of major and selected trace elements in an Orinoco River tributary coming from the Andes,Venezuela

The analysis of physicochemical variables and selected dissolved elements was performed on the Apure River waters for 15 months. The variables pH, alkalinity, dissolved O₂, conductivity and Na, Ca, Mg and Cd concentrations showed maximum values during low water, whereas K, Si, Fe, Al, Mn, Zn, Cu, Cr and dissolved organic carbon (DOC) showed maximum concentrations during rising and high water. Five important factors were found to control the amount and temporal variability of the dissolved elements: lithology, hydrology, vegetation–floodplain processes, redox conditions and organic complexation. Weathering of silicates, carbonates and evaporites in the Andes provides most of the proportion of Na, Ca, Mg and HCO₃^? to waters. The temporal variability of these ions is controlled by a dilution process. Although Si can be taken up by the biomass, Si and K can be leached from the floodplain by weathering of clays. Microbial decay of the submerged plants in the floodplain during the inundation periods provides DOC and K to river waters and changes the redox conditions in water. The changing redox conditions control the solubility of Mn, Zn and Fe. Dissolved Mn is a function of pH‐dependent redox process, whereas Zn solubility is controlled by scavenging of Zn during the oxidation of Mn²⁺ to MnO₂. Positive relationships between Al, Fe, Cu, Cr and DOC suggest that these elements are complexed by organic colloids generated in the floodplain. Moreover, the binding capacity of Fe with DOC increases under reducing conditions. Although Cd seems to be provided by weathering in the Andes, several processes can affect the mobility of Cd during transport. Copyright © 2010 John Wiley & Sons, Ltd.     

Geochemical characteristics of organic matter-rich strata of lower Cambrian in Tarim Basin and its origin

The organic matter-rich strata of the Yurtusi Formation of Lower Cambrian are wildly spread and steady in the Tarim Basin, in which cherts are developed, companied with phosphorite. Al/(Al+Fe+Mn) ratio and Si/(Si+Al+Fe) ratio of cherts range from 0.0023 to 0.0046 and 0.965 to 0.98, respectively, suggesting that cherts are formed in submarine hydrothermal activity and far away from terrestrial. Trace elements, such as As, Hg, Pb, Zn, Cu, Co, P, V, Ba, etc., are markedly rich in organic matter-rich sedimentary rocks of which Ba/Sr ratios are between 21.2 and 158.1. Compared with modern hydrothermal sediments, their Ba/Sr ratios are similar, it indicates that the organic matter-rich strata have the geochemical feature of submarine hydrothermal sediments. The total content of rare earth elements (ЕREE) in cherts is from 8.81 to 56.682 μg/g, on average 31.41 μg/g and the ΕREE of cherts is between continental margin chert's and abyssal chert's. The LREE/HREE ratio of cherts varies from 1.01 to 3.56, which reveals the characteristics of hydrothermal sediments. There is positive correlation between the total organic content (TOC) and Ba/Sr ratio which is geochemical index of submarine hydrothermal activity, which indicates that the submarine hydrothermal activity obviously influences the richness of organic matter in the Yurtusi Formation.     

Flood effects on phosphorus immobilisation in a river water filled pit lake—Case study Lake Goitsche (Germany)

Between 1999 and 2002, a former open-cast mine was filled with river water forming the recent Lake Goitsche. During filling initially acid water was neutralised. Phosphorus (P) imported from Mulde River was nearly completely removed from the water column by co-precipitation with iron (Fe) and aluminium (Al) and deposited in the sediment.During extremely high waters of the Mulde River in 2002, a dike breach facilitated a second high import of P into Lake Goitsche with suspended and dissolved matter. The analysis of total phosphorus (TP), however, showed that P again had been eliminated from the water body a few months after the flood event. Sediment investigations before filling with river water, during filling, and after the flood event were used to analyse the process of P immobilisation in a lake with acid mine drainage history.The ratios of Fe to soluble reactive P (SRP) of sediment pore water were up to three orders of magnitudes higher than in natural lakes and can serve as an indicator for potential internal P loading from sediments. The SRP concentrations at the oxic/anoxic boundary were near or below the limit of quantification (< 0.2 μmol/L). Fe and manganese (Mn) redox cycling were responsible for hindering P dissolution from sediment to lake water.Finally it can be stated, that the risk of eutrophication for such a lake seems to be low.     

Investigations on Mineralogical and Chemical Composition of Suspended Particulate Matter (SPM) in the Odra Estuary

In order to recognize lateral and seasonal variations in composition of suspended particulate matter (SPM) in the Odra Estuary, samples were taken at four sites in the period July 1996 - July 1997 monthly if possible. The contents of the elements Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P, C, S as well as Ba, Cr, Sr, V, Zn, Cu, Zr, and of the minerals illite, chlorite, smectite, kaolinite and others have been determined. The decreasing influence of the river Odra towards the open sea could be realized with the help of the contents of the minerals quartz, smectite, and of the elements Ba, Cr, K, P, Si and other. 60% of the seasonal and lateral variations can be explained by changing contents of total carbon (TC), total organic carbon (TOC), Al, Fe, Si, Ti, P, Mn, and Ba. They are mainly caused by differences in the production of organic matter, resuspension, riverine input, and redox-sensitive processes.     

Temporal and spatial variations in the geochemistry of major and minor particulate and selected dissolved elements of Thermaikos Gulf, Northwestern Aegean Sea

The objectives of this study were to examine both spatial and temporal changes of particulate major elements and minor metals, as well as dissolved Mn and Cd, in the waters of Thermaikos Gulf. Collections of water and suspended particulate matter (SPM), as depth profiles (5–8 depths), were undertaken at 10 principal stations, essentially on a N–S traverse of the western side of the Gulf.One of the principal aims of the study was to observe if there was any change in the patterning of the elements between the three occupations of the stations: (a) in September 2001, immediately before the commencement of trawling; (b) in October 2001, whilst fishing was active; and (c) in winter/early spring conditions (February 2002), when fishing was still active, but after a change of river/atmospheric conditions.Bottom (20 m) waters were dominated by sediment resuspension; this was identified by concentration changes in the aluminosilicate elements (e.g. Al, Ti, K, Fe) of the SPM. A two- to three-fold increase occurred between September and October, caused probably by trawling; this was sustained at the offshore stations, in February. During February, the western inshore stations showed little sediment resuspension, caused by extreme winter cooling and the sinking of water. Consequently, a N–S density discontinuity existed at all water depths, which prevented the thermohaline cyclonic circulation from penetrating into the western seaboard of the Gulf. The distribution of dissolved and particulate Mn in the lower waters was due to redox cycling of the element at the benthic boundary; this was more intense in the north, where the organic supply was higher.Biogenic element concentrations and Ca/Al, Si/Al ratios showed no evidence that trawling activity promoted higher biological production. Strong correlations of Co, Cr, Ni and V, with Al and K, showed that these elements were associated strongly with detrital aluminosilicates. However, the variable association of Cd, Pb and Zn, with K (and Al), especially in the upper waters, implied an anthropogenic source derived from the rivers and the city of Thessaloniki. Examination of the Kd's of Cd showed a two-order of magnitude decrease with depth, caused by resuspension and possible advection of relatively unpolluted sediments, into the western Gulf.     

Iron oxidation state in lower mantle mineral assemblages: II. Inclusions in diamonds from Kankan, Guinea

Inclusions of ferropericlase and former (Mg,Fe)(Si,Al)O₃ perovskite in diamonds from Kankan, Guinea believed to originate in the lower mantle were studied using Mössbauer spectroscopy to determine Fe³⁺/ΣFe. Fe³⁺ concentration in the (Mg,Fe)(Si,Al)O₃ inclusion is consistent with empirical relations relating Fe³⁺/ΣFe to Al concentration, supporting the inference that it crystallised in the perovskite structure at lower mantle conditions. In ferropericlase there is a nearly linear variation of trivalent cation abundance with monovalent cation abundance, suggesting a substitution of the form Na_0.5M_0.5³⁺O (M=Fe³⁺, Cr³⁺, Al³⁺). Excess positive charge is likely balanced by cation vacancies, where their abundance is observed to increase with increasing iron concentration, consistent with high-pressure experiments. The abundance of cation vacancies is related to oxygen fugacity, where ferropericlase inclusions from Kankan and São Luiz (Brazil) are inferred to have formed at conditions more oxidising than Fe-(Mg,Fe)O equilibrium, but more reducing than Re-ReO₂ equilibrium. Fe²⁺/Mg partition coefficients between (Mg,Fe)(Si,Al)O₃ and ferropericlase were calculated for inclusions co-existing in the same diamond using Mössbauer data and empirical relations based on high-pressure experimental work. Most values are consistent with high-pressure experiments, suggesting that these inclusions equilibrated at lower mantle conditions. The measured ferropericlase Fe³⁺ concentrations are consistent with diamond formation in a region of redox gradients, possibly arising from the subduction of oxidised material into reduced lower mantle. Reduction of carbonate to form ferropericlase and diamond is consistent with a slight shift of Kankan δ¹³C values to isotopically heavy compositions compared to the worldwide dataset, and could supply the oxygen necessary to satisfy the high Fe³⁺ concentration in (Mg,Fe)(Si,Al)O₃ perovskite, as well as account for the high proportion of ferropericlase in the lower mantle paragenesis. The heterogeneity of lower mantle diamond sources indicates that the composition of lower mantle diamonds do not necessarily reflect those of the bulk mantle.     

The distribution of trace metals in Florida Bay sediments

The distribution of trace metals based on surface sediments collected at 40 stations across Florida Bay was done in June, November and February 2000-2001. Concentrations of Sc, V, Ba, Cd, Cr, Co, Cu, Pb, Mn, Ni, Zn, Al and Mg were determined by ICP-MS, and the total Fe was determined by spectrophotometry. Organic carbon (OC), nitrogen (N), and calcium carbonate (CaCO3) were also measured. Eleven of 13 metals showed a similar distribution pattern for the various months studied. Maximum concentrations of metals were lower than those found in most estuarine systems and were concentrated in the north-central and western zones of the Bay. The Mn and Fe concentrations, unlike the other metals, gradually decreased from north (Everglades) to south (Florida Keys). Some metals (Ni, Zn, Cu, Cr, Pb and Ba) associated with petroleum use showed high concentrations at stations near the Tavernier marina. Florida Bay sediments are predominately CaCO3 (65.9-92.5%). The greatest value for OC (5.5%) and the lowest value of CaCO3 (65.9%) were found in the western zone. Trace metal distribution patterns are similar to the OC and N in the sediments. There was a strong correlation between most metals (V>Cu>Ni>Cr>Al>Co>Ba>Zn>Pb>Mg) and the percentage of OC. The maximum C/N values (9-12) were observed at the stations with the highest OC, where dense colonies of seagrass are found and most of the metals are concentrated. All metals except Mg, Mn and Co showed a strong correlation with Al and the fine fraction of the sediments (aluminosilicates) associated with continental input and river runoff.