洪泽湖入湖河流沉积物有机磷分布特征及外源输入对其形态转化的影响

为探究洪泽湖入湖河流沉积物有机磷的空间分布及外源输入对其形态转化的影响,本文利用Ivanoff法开展有机磷形态特征研究,并通过实验室添加常见外源有机质和铁离子,深入探讨外源物质对沉积物有机磷形态变化的长期影响.研究结果表明,洪泽湖入湖河流沉积物有机磷含量范围为34.8～398.6 mg/kg,占总磷的7.7%～36.9%,其中非活性有机磷(NOP)>中活性有机磷(MLOP)>活性有机磷(LOP).濉河沉积物LOP平均占比为19.4%,高于其他河流,而成子河NOP平均占比最高,为56.41%,表明有机磷的空间分布不均匀.总体而言,安河和濉河沉积物中总氮、总磷和有机磷含量显著高于成子河和淮河,显示前两条河流有较高的污染水平.冗余分析表明河流沉积物有机磷形态明显受到其理化性质影响,而不同污染程度沉积物的影响因素有所不同.外源物质添加能够活化沉积物的有机磷,促使NOP向LOP和MLOP转化,有机质输入引起的沉积物有机磷形态变化要大于铁元素输入,而外源物质输入对污染较重河流沉积物的有机磷转化作用更为显著.因此,减少入湖河流周边的外源污染排放是减少湖泊生物可利用磷的有效途径.     

滇池表层沉积物铵态氮吸附特征

为研究滇池内源污染特征,2013年利用GIS软件针对滇池全湖布设36个采样点,采集表层沉积物,研究滇池表层沉积物铵态氮(NH_4+-N)吸附特征,同时分析沉积物的理化性质对NH_4+-N吸附特性的影响.结果表明:滇池表层沉积物对NH_4+-N的吸附量在前2 h之内呈增长趋势,吸附速率较大,之后沉积物对NH_4+-N的吸附量不随时间变化而变化,基本达到平衡,最大吸附速率均发生在0~5 min内;不同区域表层沉积物NH_4+-N最大吸附速率平均值表现为:外海南部湖心区外海北部草海,最大吸附量平均值表现为:湖心区外海南部外海北部草海,吸附效率平均值表现为:外海北部草海湖心区外海南部;沉积物对NH4+-N的吸附量与NH_4+-N的初始浓度大致呈线性关系,并且低浓度下表现出很好的吸附/解吸特征;滇池表层沉积物NH_4+-N的吸附解吸平衡浓度(ENC0)高于上覆水中NH_4+-N浓度,表明沉积物中NH_4+-N有向上覆水中释放的风险,沉积物在很长一段时间内起到水体污染"源"的作用;ENC0与沉积物中总氮、NH_4+-N含量呈显著正相关,本底吸附量和有机质总量呈显著负相关,沉积物吸附NH_4+-N主要受有机质的影响.     

The role of vegetation in the retention of fine sediment and associated metal contaminants in London's rivers

Many urban rivers receive significant inputs of metal‐contaminated sediments from their catchments. Restoration of urban rivers often creates increased slack water areas and in‐channel vegetation growth where these metal‐contaminated sediments may accumulate. Quantifying the accumulation and retention of these sediments by in‐channel vegetation in urban rivers is of importance in terms of the planning and management of urban river restoration schemes and compliance with the Water Framework Directive. This paper investigates sediment properties at four sites across three rivers within Greater London to assess the degree to which contaminated sediments are being retained. Within paired restored and unrestored reaches at each site, four different bed sediment patch types (exposed unvegetated gravel, sand, and silt/clay (termed ‘fine’) sediments, and in‐channel vegetated sediments) were sampled and analysed for a range of metals and sediment characteristics. Many samples were found to exceed Environment Agency guidelines for copper (Cu), lead (Pb) and zinc (Zn) and Dutch Intervention Values for Cu and Zn. At all sites, sediments accumulating around in‐channel vegetation were similar in calibre and composition to exposed unvegetated fine sediments. Both bed sediment types contained high concentrations of pseudo‐total and acetic acid extractable metal concentrations, potentially due to elevated organic matter and silt/clay content, as these are important sorbtion phases for metals. This implies that the changed sediment supply and hydraulic conditions associated with river restoration may lead to enhanced retention of contaminated fine sediments, particularly around emergent plants, frequently leading to the development of submerged and emergent landforms and potential river channel adjustments. High pseudo‐total metal concentrations were also found in gravel bed sediments, probably associated with iron (Fe) and manganese (Mn) oxyhydroxides and discrete anthropogenic metal‐rich particles. These results highlight the importance of understanding the potential effects of urban river restoration upon sediment availability and channel hydraulics and consequent impacts upon sediment contaminant dynamics and storage. Copyright © 2014 John Wiley & Sons, Ltd.     

长江中游湖泊表层沉积物多环芳烃的分布、来源特征及其生态风险评价

为明确长江中游地区湖泊沉积物中多环芳烃（PAHs）的分布特征、来源及其生态风险,于2018年7月采集了该地区12个湖泊的表层沉积物样品.采用气相色谱-质谱联用仪（GC-MS）测定了沉积物中16种PAHs的含量.结果表明：12个湖泊沉积物中均检测出16种优控PAHs,PAHs的总含量在572.7~1766.2 ng/g （dw）之间（均值为976.5±285.0 ng/g （dw））.武汉市东湖沉积物中PAHs含量最高,达到1634.8±111.4 ng/g （dw）.与国内外其他地区湖泊沉积物相比,长江中游地区湖泊沉积物中PAHs含量高于国内偏远地区的抚仙湖、青海湖及博斯腾湖,低于东部地区的巢湖、太湖及美国经济工业发达地区的湖泊.根据单体PAH的聚类分析结果,12个湖泊可以分成3种类型,类型1主要以低环为主,占比为64.04%±7.02%,类型2低环和中高环分布相对平均,分别为50.76%±5.17%和49.24%±5.17%,类型3低、中、高环分布相对平均,占比分别为35.35%±3.56%、26.17%±0.45%和38.48%±3.84%.综合该区域PAHs的分布特征及异构体比值法与主成分分析法的结果表明,类型1湖泊沉积物中PAHs主要来源为煤炭、木材等生物质的燃烧源;类型2和类型3湖泊沉积物中PAHs主要来源为煤炭、木材等生物质的低温燃烧以及机动车等燃烧汽油、柴油的尾气排放和工业炼焦等化石燃料的高温燃烧源.沉积物中PAHs与总有机碳（TOC）之间显著的相关性表明,沉积物中TOC含量是影响长江中游湖泊沉积物中PAHs归趋分布的主要因素.长江中游流域湖泊沉积物中PAHs的RQ_NCs值均小于800,且RQ_MPCs值大于1的风险商值法生态风险评价结果表明,长江中游流域湖泊表层沉积物中PAHs整体呈中等风险水平.     

Germination and establishment of the invasive cordgrass Spartina densiflora in acidic and metal polluted sediments of the Tinto River

Heavy metal pollution is common in rivers in the vicinity of mining areas. In these polluted environments, the survival of alien species with a high tolerance to metals may be favored. The Tinto River (Southwest Iberian Peninsula) is an excellent natural laboratory for the study of plants’ responses to acidic and metal polluted sediments. This work analyzes the tolerance of the alien species Spartina densiflora to low pH and high metal loads in the Tinto River. The main aim of this study was to determine if this alien species can invade landward along the banks of the Tinto River. S. densiflora seeds were able to germinate in heavy metal polluted aerobic sediments even at pH 2. However, these conditions decreased S. densiflora final germination, altered germination dynamics, decreased aerial and subterranean growth rates, and prevented its establishment.     

Aliphatic and aromatic hydrocarbons in marine biota and coastal sediments from the Gulf and the Gulf of Oman

The composition and spatial distribution of aliphatic and polycyclic aromatic hydrocarbons (PAHs) were investigated in biota and coastal sediments from four countries surrounding the Gulf (Bahrain, Qatar, United Arab Emirates and Oman). The levels of total petroleum hydrocarbons (TPH), aliphatic unresolved mixture and PAHs in sediments and biota were relatively low compared to world-wide locations reported to be chronically contaminated by oil. Only in the case of the sediments collected near the BAPCO oil refinery in Bahrain, having concentrations of 779 μg g⁻¹ total petroleum hydrocarbon equivalents and 6.6 μg g⁻¹ ∑PAHs, can they be categorized as chronically contaminated. Some evidence of oil contamination was also apparent in sediments and bivalves around Akkah Head and Abu Dhabi in the UAE, and near Mirbat in Oman. Contaminant patterns in sediments and biota indicated that the PAHs were mainly from fossil sources, with the exception of the high PAH concentrations in sediments near the BAPCO refinery that contained substantial concentrations of carcinogenic PAH combustion products.     

鄱阳湖西侧周边农村水塘夏季表层沉积物氮、磷、有机质分布特征及评价

水塘作为农村重要的水生态系统,其环境状况与人们生产生活和健康密切相关。为了解鄱阳湖西侧周边农村水塘沉积物的有机质和营养盐赋存状况,于2018—2019年对鄱阳湖流域西侧附近4个县的23个水塘进行沉积物营养盐的分析,同时通过相关分析和差异性分析对其来源进行解析,并采用综合污染指数评价法和主成分分析法对水塘沉积物的污染程度进行评价。结果表明：水塘沉积物污染物含量较高,其有机质、有机碳（TOC）、总氮（TN）和总磷（TP）含量分别为5.81%±2.16%、2.46%±1.02%、（6.48±2.35） mg/g和（1.89±0.80） mg/g。3种形态的无机氮中铵态氮含量最高,其次为硝态氮和亚硝态氮。沉积物TP受到洗涤废水的影响较大,清淤和活化显著减轻了沉积物TN和TOC污染。综合污染指数评价结果表明重度污染和中度污染的水塘占比分别为95.65%和4.35%,其平均评价结果为重度污染,表明水塘沉积物污染严重。而主成分分析结果表明P18水塘污染最重,而P6水塘污染最轻。综合污染指数与主成分分析总得分的相关系数为0.92,表明两者的评价结果较为一致。本研究通过分析鄱阳湖西侧农村水塘的沉积物营养...     

鄱阳湖“五河”入湖口沉积物中微塑料污染物的特征及其时空分布

微塑料作为新型环境污染物正日益受到人们密切关注,为探索微塑料在鄱阳湖流域的污染状况,以鄱阳湖流域"五河"入湖口的沉积物为研究对象,分别在3个水文周期（平水期、丰水期和枯水期）选择6个典型区域采集沉积物进行分析.采用浮选分离方法及金相显微鉴定技术,分析鄱阳湖"五河"入湖口沉积物中微塑料的类型、丰度和表面形貌等特征,旨在揭示鄱阳湖沉积物中微塑料的空间分布规律及不同水位期的动态变化.研究结果显示微塑料的类型有碎片类、发泡类、薄膜类和纤维类,其中主要以碎片类微塑料为主,所占百分比为51.95%;70%的微塑料粒径<1 mm,微塑料（<5 mm）的平均丰度为811.11 n/kg,6个样点的微塑料丰度值表现为朱港 > 吴城 > 渡头乡 > 龙口 > 瑞洪镇 > 南矶山.6个样点的微塑料丰度值与鄱阳湖水位动态均具一致性,在枯水期所占比例最高,达到44.41%;平水期次之,达到31.52%;丰水期所占比例最低,仅占24.07%.不同水期、不同样地存在不同程度的微塑料污染问题警示人们要重视塑料垃圾的排放及其污染问题,以减少对湖泊、河流等湿地生态环境的影响.     

祁连盆地第三纪沉积物磁性地层和岩石磁组构初步研究

祁连山山间盆地内的新生代沉积物是研究新生代以来祁连山构造演化的重要材料.本文以位于祁连山中部祁连盆地内的新生代沉积物为研究对象,利用磁性地层学方法结合碎屑颗粒裂变径迹定年方法获取其沉积时代框架,在此基础上,结合岩性变化与沉积环境变迁分析祁连山构造演化历史.野外实测剖面显示该盆地内的第三系可划分为下部砾岩组和上部砂岩组两大岩性单元.古地磁结果显示砾岩组的沉积时代约为10-14.3 Ma.砾岩组沉积大约在14.3 Ma开始形成,指示祁连山14.3 Ma以来构造活动变强烈.磁组构结果显示砾石组顶部沉积形成时的受力方向与现今祁连盆地周缘断层分布所指示的应力方向一致,表明这些断层大约在10 Ma附近开始活动.我们的结果揭示祁连山中部山脉14.3 Ma以来尤其在10 Ma附近构造活动较强烈.这与过去低温热年代学所获得的祁连山山体的快速冷却年龄及祁连山两端大型盆地内的第三系所记录的构造事件发生的时间基本吻合.而砂岩组的古地磁结果并未通过褶皱检验,其古地磁记录发生了后期重磁化,无法获得地层的准确沉积年龄.     

Matrix bound phosphine in sediments of the yellow sea and its coastal areas

Matrix bound phosphine (MBP), a kind of chemically reduced phosphorus, has received limited attention in prevailing modeling of the phosphorus biogeochemical cycle. MBP has been found to occur in marine sediments. MBP in the sediments of the Yellow Sea and its coastal areas was measured by gas chromatography from 2004 to 2007. MBP levels in surface sediments were 0.19–38.24 ng kg⁻¹ in the shelf of the Yellow Sea, 0.34–17.15 ng kg⁻¹ in the Jiaozhou Bay, 2.11–71.79 ng kg⁻¹ in the Sanggou Bay and 0.28–319.32 ng kg⁻¹ in the rivers around the Jiaozhou Bay. High levels of MBP occurred in the northern and middle areas of the Yellow Sea. Obvious seasonal variation of MBP was observed in surface sediments of the Sanggou Bay, with the highest MBP level occurring in summer and the lowest in winter. MBP in surface sediments of the inner Jiaozhou Bay was higher than those in the outer region. MBP levels increased with depth in the top 5–10 cm sediments of the Jiaozhou Bay and on the intertidal flats. Environmental factors such as type of sediments, temperature, organic matter and human activity were found to affect the concentrations and distribution of MBP in marine sediments.     

The effects of oil exploration and production in the Fladen Ground: composition and concentration of hydrocarbons in sediment samples collected during 2001 and their comparison with sediment samples collected in 1989

Due to the potentially accumulative nature of the Fladen Ground, an area of intense oil activity in the North Sea, a survey was carried out in 1989 to map the distribution of contamination in relation to these oil activities. All the sediments collected were screened by ultraviolet fluorescence (UVF) for polycyclic aromatic hydrocarbons (PAHs) and selected samples were analysed for n-alkanes (by GC-FID), PAHs and biomarkers (by GC-MSD). This survey was repeated in 2001, with all the 1989 sites being resampled. All of these sediments were analysed for UVF oil equivalents, PAHs, n-alkanes and biomarkers. The concentrations of these parameters decreased between 1989 and 2001, with average decreases ranging from 43% to 88%. In addition, no significant difference was found, for all the parameters, between near field (<5 km from an oil installation) and far field (>5 km from an oil installation) sites in 2001 indicating that the Fladen Ground is approaching a 'steady state' or background concentration for contamination.     

Thallium Distribution in Sediments from the Pearl River Basin,China

Thallium (Tl) is a rare element of high toxicity. Sediments sampled in three representative locations near industries utilizing Tl‐containing raw materials from the Pearl River Basin, China were analyzed for their total Tl contents and the Tl contents in four sequentially extracted fractions (i.e., weak acid exchangeable, reducible, oxidizable, and residual fraction). The results reveal that the total Tl contents (1.25–19.1 µg/g) in the studied sediments were slightly high to quite high compared with those in the Chinese background sediments. This indicates the apparent Tl contamination of the investigated sediments. However, with respect to the chemical fractions, Tl is mainly associated with the residual fraction (>60%) of the sediments, especially of those from the mining area of Tl‐bearing pyrite minerals, indicating the relatively low mobility, and low bioavailability of Tl in these sediments. This obviously contrasts with the previous findings that Tl is mainly entrapped in the first three labile fractions of the contaminated samples. Possible reasons were given for the dominating association of Tl with the residual fraction (>95%) of the mining area sediments. The significant role of certain K‐containing silicates or minerals of these sediments on retaining Tl in the residual fraction, discovered by this study, provides a special field of research opportunity for the Tl‐containing wastewater treatment.     

滇池福保湾间隙水氮磷分布及其与底泥微生物和磷酸酶相互关系

在滇池福保湾不同区域应用Peeper(渗析膜式)技术,分析了底泥间隙水NH4 -N、Po43--p的垂向分布特征和近表层10cm内底泥的微生物活性(FDA)、碱性磷酸酶活性(APA),并对它们之间的相互关系进行了统计分析.结果表明,NH4 -N和Po43--p浓度自上覆水向下层间隙水呈先升后降趋势,反映它们有自间隙水向上覆水扩散的潜在危害;底泥有机质(Loss-on-Ignion,LOI)、APA和FDA活性也有从表层底泥向下层逐步降低的趋势.在空问分布上,Po43--p浓度变化为河口区>湾心区>西部沿岸区>东部沿岸区,与沉积物中LOI、APA和FDA活性的大小顺序基本相同.间隙水NH4 6-N浓度与表层10cm内底泥的APA和FDA活性具有显著正相关性(α＝0.01).Po43--p浓度与底泥APA和FDA活性具有负相关性.但相关系数很低.     

Distribution and partitioning of polycyclic aromatic hydrocarbons (PAHs) in different size fractions in sediments from Boston Harbor, United States.

The concentrations of 16 US EPA priority pollutant polycyclic aromatic hydrocarbons (PAHs) were analyzed in four size fractions (< 62, 62-125, 125-250, and > 250 microm) in three contaminated Boston Harbor sediments. Total PAH concentrations ranged from 7.3 to 358 microg/g dry wt. and varied largely among the different size fractions in these sediments. For all three sites, the highest PAH concentrations were associated with the large size (> 250 microm) fractions while the fine silt and clay fractions (< 62 microm) contained relatively low PAHs. Despite the great concentration differences, the composition of PAHs in the four size fractions of these sediments showed similar patterns dominated by PAHs with three or more rings. By examining the distribution patterns of selected alkyl homologs to parent compounds, the results indicate that the major PAHs contributing to the high contamination in the inner harbor sediments were from pyrogenic sources. A positive correlation between PAHs and sedimentary organic carbon exists for all size fractions in the sediments. Calculated organic carbon normalized partition coefficients (log K(oc)) for selected major PAHs indicate near-equilibrium partitioning of PAHs among the different size fractions despite their large concentration variations. Sedimentary organic matter associated with different size fractions was the controlling factor for the observed distribution differences of PAHs among the size fractions. Our results also suggest that sedimentary organic matter with different origins and maturities may have somewhat different PAH sorption characteristics. Particulate organic matter of charcoal, plant detritus and Capitella fecal pellets in the sediments appear to sorb PAHs more strongly than organic matter associated with clay minerals. The strong association of PAHs with these organic particles in sediments will have a great influence not only on their distribution but also on long-term environmental impact.     

The distributions of particulate heavy metals and its indication to the transfer of sediments in the Changjiang Estuary and Hangzhou Bay,China

Particulate heavy metals (Cu, Pb, Cd) were measured following intensive sampling in June and October 1994 at 70 stations in the Changjiang Estuary and Hangzhou Bay, China. In the study area, particulate Cu and Pb have a similar level that is higher than the concentration of particulate Cd. Cu, Pb and Cd concentrations in suspended sediments are higher than those in bed load. In the middle of Hangzhou Bay, heavy metal concentrations in suspended sediments and bed load are similar. This may be the result of the frequent exchange between them, which is due to the strong dynamic condition. A negative relationship was observed between concentrations of heavy metals in bed load and bulk density. Fine-grained sediments were the main carriers of heavy metals. Sedimentary dynamics dominate the fate of heavy metals in these sites. The distributions of metals (especially Cu) in suspended sediments can indicate the transfer of sediments in this area.     

A Nd isotope investigation of sediments related to crustal development in the British Isles

The times of original fractionation of the Sm and Nd component of clastic sediments from a mantle source (≡ crustal residence age) have been estimated from Sm-Nd model ages calculated relative to a depleted mantle evolution. In this way the provenance and evolution of selected Precambrian and Phanerozoic sediments and metasediments from the British Isles have been examined. Whereas some Archaean and early Proterozoic sediments have Sm-Nd model ages that are close to their stratigraphic age, the Phanerozoic sediments analysed have model ages as much as 2.0 Ga in excess of their stratigraphic age.A more detailed study of Lower Palaeozoic sediments deposited on the northern margin of the Iapetus Ocean provides evidence for a marked change of provenance in the Ordovician after the deposition of the Dalradian Supergroup. A component with comparatively high¹⁴³Nd/¹⁴⁴Nd and Sm/Nd ratio (presumably basaltic) is present in the sediments throughout the accretionary prism. Crustal residence age estimates average about 1.5 Ga for both these Lower Palaeozoic sediments, and modern pelagic clays, and collectively fail to provide any evidence for significant continental growth during the Phanerozoic.     

Recovery simulations of grossly polluted sediments in the Bilbao Estuary

The Bilbao Estuary is one of the most contaminated estuaries on the north coast of Spain, and vast efforts have been made to abate pollution there. In fact, the local water authority has forecast a biological recovery of the native fauna after a substantial increase in dissolved oxygen to normoxic levels. In order to assess this prediction by evaluating the extent of natural regeneration of these polluted sediments, two long-term bioassays (t=90 d) were performed. In both of them, lethal (differences in survival) and sublethal (differences in length and weight growth) effects were measured by using juvenile individuals of the autochthonous clam, Scrobicularia plana (Da Costa, 1778). The sediments tested differed in pollution levels, as measured by a set of indicators including PAHs, PCBs, heavy metals, volatile organic matter and coprostanol. All sediments were finally exposed to normoxic conditions in situ in the Bilbao Estuary (DO approximately 6.3 mg l(-1)). In the first experiment, concerning moderately polluted sediments from the Bilbao Estuary and reference sediments from the "pristine" Plentzia Estuary, no significant differences (P>0.05) were found regarding animal survival (approximately 94.5%) or growth in length or weight between the sediments tested. In the second experiment, also involving grossly polluted sediments (GPS) from the Bilbao Estuary, survival (24.5%) was statistically lower (P<0.05) than in the other sediments (approximately 93%). No significant differences were found in growth (length, weight) between animals exposed to moderately polluted or reference sediments. We interpret this dramatic difference in survival as the lethal effect on the animals tested of the GPS of the Bilbao Estuary, indicating a situation where biological recovery is not possible due to the adverse consequences of contaminants sorbed into sediments. The extensive use of this inexpensive bioassay could help to distinguish sediments in which homeostatic recovery is possible from grossly polluted "hot spots", which need costly remedial actions.     

Trace metal remobilization in the interstitial waters of red clay and hemipelagic marine sediments

Interstitial water samples from the Guatemala Basin and the coast of Baja California have been analyzed for manganese, iron, copper, nickel and nitrate. The data provide a systematic look at changes in trace metal diagenesis proceeding from red clay to highly reducing nearshore sediments.In red clay sediments, the nitrate concentrations suggest that only aerobic respiration is occurring. Manganese and iron are below detection. Nickel concentrations remain the same as in bottom seawater but copper shows a pronounced maximum just at the sediment/water interface. Proceeding to hemipelagic sediments, denitrification becomes increasingly important and manganese and iron remobilization occur in the sediments.The linear manganese and nitrate profiles suggest regions of production or consumption separated by zones of diffusion. This differs from the conventional picture of a continuous series of reactions within the sediments. Manganese reduction always occurs before iron reduction. The pore water nickel correlates well with manganese in these sediments, suggesting that nickel is associated with MnO₂ in the solid phase. The pore water flux ratio of manganese and nickel agrees well with the ratio in solid phase authigenic oxides. Copper still displays a core top concentration maximum as well as a second maximum associated with the remobilized manganese. The calculated ratio of the Cu/C flux ratios support the argument for copper remobilization during organic carbon oxidation. Comparison of the upward and downward diffusive fluxes with the rate of copper buried by sedimentation shows that at least half of the copper buried must be of diagenetic origin and less than 25% of the copper reaching the sediments is buried.     

Chemical speciation of polycyclic aromatic hydrocarbons in sediments: Partitioning and extraction of humic substances

The primary objective of this study was to examine the chemical speciation of polycyclic aromatic hydrocarbons (PAHs) found in sediments endowed with different characteristics. To achieve this purpose and because the nature of the sediments influences the distribution of PAHs, we have analyzed four different types of sediments. To study the role of organic matter in the sequestration of PAHs, we fractionated humic substances into humic acids and humin-mineral fractions. After their separation and purification, the humic components were examined for their sorptive reactivity by extracting them with organic solvents; these extracts were subsequently subjected to GC/MS analysis. Our results show that PAHs are distributed between labile and sequestered fractions in sediments. A slower uptake of PAHs occurs when the sequestered fraction is formed, and this process can be prolonged and may be influenced by the characteristics if the sediment. Our study suggests that organic contaminants are available in muddy sediments for a longer period of time than in sandy sediments.     

Organochlorine micropollutants in the Jiulong River Estuary and Western Xiamen Sea, China

Organochlorine contaminants including 12 polychlorinated biphenyl (PCB) congeners and 18 insecticides were determined in water, pore water and sediments of the Jiulong River Estuary and Western Xiamen Sea, China. The results showed that the levels of the total PCBs ranged from non-detectable to 1500 ng l⁻¹ in water, from 209 to 3870 ng l⁻¹ in pore water, and from 2.78 to 14.8 ng g⁻¹ dry weight in sediments. Total organochlorine insecticide concentrations were from below the limit of detection to 2480 ng l⁻¹ in water, from 267 to 33400 ng l⁻¹ in pore water, and from 4.22 to 46.3 ng g⁻¹ dry weight in sediments. Concentrations of PCBs and insecticides in pore water were significantly higher than those in surface water, due to the high affinity of these hydrophobic compounds for sediment phase. The PCB congeners with the highest concentrations were CB153, CB180 and CB194, which together accounted for 68–87% of total PCBs in water, pore water and sediment. Among the hexachlorocyclohexane (HCH) compounds, beta-HCH was found to be a major isomer. Analysis of 1,1,1-trichloro-2,2-bis-chlorophenyl-ethane (DDT) and its metabolites showed that 1,1-dichloro-2[o-chlorophenyl]-2[p-chlorophenyl]-ethylene (DDE) was dominant in the group. In comparison to a 1998 study in the Western Xiamen Sea, levels of organochlorines were enhanced due probably to recent inputs and changes in sediments.