Heavy metals in particulate matter and sediments in the southern Barcelona sedimentation system (North-western Mediterranean)

Concentrations of selected heavy metals (Cr, Cu, Ni, Pb and Zn) from surface sediments, suspended particulate matter and settling particles in the southern Barcelona continental margin were studied in order to evaluate the environmental impact of the anthropogenic metals discharged by the Llobregat River in this Mediterranean area. The temporal variation of heavy metals discharged by this river onto the continental shelf is clearly related to the river water flow. Part of the fine sediment and associated heavy metals transported by the Llobregat River during periods of low river flow accumulate on the river bed, and they are totally removed and discharged onto the Barcelona continental shelf during sporadic river water flow increases. Metals produce significant anomalies of chromium (×2.5), copper (×3.4) and zinc (×3.7) in the surface sediments of the Llobregat prodelta and tend to be transported along the continental shelf following the mean flow. Metals associated with the finest suspended flocs transferred to the slope are controlled by the shelf-slope density front and are transported along slope by the general geostrophic current, instead of accumulating and becoming concentrated in the slope bottom sediments. Settling particulate matter collected in sediment traps on the Barcelona continental slope offshore of the shelf-slope front shows low heavy metal concentrations except in a few sediment trap samples that are significantly metal-enriched in chromium (×4.5) and zinc (×6.8). This enrichment is associated with very short and sporadic river flow increases and is only recorded inside the Foix submarine canyon, which acts as a preferential conduit for the shelf-slope sediment transfer.     

象山港重金属的环境化学特征

本文根据１９９０年６月和１１月对象山港海域进行的综合环境（水文、生物、化学）调查资料,分析了水体（包括溶解态、颗粒态）和沉积物的重金属（Ｃｕ、Ｐｂ、Ｚｎ、Ｃｄ、Ｃｒ）含量,运用元素的分布规律,探讨了该区的水动力因素、生物地球化学循环和沉积环境对重金属的影响,初步揭示了象山港重金属的环境化学特征。     

Chemical speciation of trace metals in seawater: Implication of particulate trace metals

Chemical speciation of particulate metals in seawater was examined theoretically. Mass balance considerations showed that the apparent conditional stability constant, defined for organically binding metals in suspended particles, coincides with the conditional stability constant determined for the corresponding metal-organic complexes dissolved in seawater. This hypothesis suggests that some metals, which are present as organic complexes (e.g. copper), are directly associated with particulate organic matter. Metals, whose free ion is buffered by organic and/or inorganic ligands, may be used as indicators of the presence of particulate organic matter in the marine environment.     

Heavy metals in Changjiang estuarine and offshore sediments: responding to human activities

The Changjiang (Yangtze) estuarine and offshore sediments were analyzed for total heavy metals concentrations and chemical fractions.Distributions of heavy metals show typical banded diffusion pattern,with high concentrations near the river mouth and following a decreasing trend in the offshore direction.According to chemical fractions,Fe/Mn oxide fraction is the major non-residual fraction in the Changjiang estuarine and offshore sediments.Higher percentage of non-residual fraction of Pb implies that,the industrial contaminations transported via the atmosphere and river input,may affect the non-residual fraction of heavy metals.Over past fifteen years,the concentration of Pb normalizing to Al presents significant increasing trend,corresponding to the effect of human activities.By comparison of heavy metals fractions in 2003 to 2006,it has been realized that increasing water and sediment may cause a higher percentage non-residual fraction of Cu in the southern part of offshore muddy sediments.     

灰色聚类法评价长江口、杭州湾海域表层海水中的重金属污染程度

通过2007年秋季航次我国近海海洋环境的综合调查,研究了长江口与杭州湾海域表层海水中重金属汞、砷、铜、铅、锌、镉、总铬的含量与分布,利用灰色聚类法对海水中的重金属元素进行评价。参照《国家海水水质标准GB3097-1997》,通过灰类白化权函数确定海水水质分级界限及各参评指标对不同等级的聚类权,构建了海水中重金属的灰色聚类法综合评价模型。该模型能够较客观、合理地评价海水中的重金属。评价结果表明,长江口与杭州湾海域表层海水中的重金属总体情况良好,但是汞、铅含量偏高,尤其是汞。长江口外以北、杭州湾北岸口外及舟山群岛邻近海域的海水水质相对较差,陆源排污为主要影响因子。     

High molecular weight organic matter in seawater

The presence and nature of high molecular weight organic matter in seawater was critically reviewed and its biogeochemical cycle was discussed.Organic matter that passes through a filter of 0.5–1 μm pore size is called dissolved and that which does not pass through such a filter is defined as particulate. The size of colloidal particles ranges from 0.001 to 1 μm, and therefore, they are included in the dissolved fraction having high molecular weight.High molecular weight organic matter greater than 100,000 molecular weight was found in the seawater of Tokyo Bay. The values ranged from 0.1 to 1.5 mgC/l, and accounted for 8–45% of the total dissolved organic matter.Decomposition experiments on dissolved organic matter showed that macromolecular organic matter is refractory to bacterial attack. However, macromolecular organic materials tend to aggregate or adsorb on small particles to a sufficient size for precipitation. Organic aggregates thus formed sink to the bottom of the sea and bioelements included in them are removed from water column. High molecular weight organic materials are, therefore, considered to play an important role in transportation and distribution of matter in seawater.In order to elucidate the chemical and biological properties of macromolecular organic matter, concentration and isolation of this material are important, using methods such as adsorption on organic adsorbents or ultrafiltration.     

Removal of trace metals from seawater during a phytoplankton bloom as studied with sediment traps in Funka Bay,Japan

To study biological effects on the particulate removal of chemical elements from seawater, sediment trap experiments were carried out successively ten times throughout the spring phytoplankton bloom in Funka Bay. Sediment traps were deployed every one to two weeks at 1, 40 and 80 m depths. The settling particles obtained were analyzed for trace metals, phosphate and silicate. The propagation of diatoms in spring results in larger particulate fluxes than that of dinoflagellates. The biogenic silicate concentration is higher in the earlier period, when diatoms are predominant, than in the subsequent period, when dinoflagellates are predominant. The concentrations of aluminum, iron, manganese and cobalt in the settling particles comprising largely biogenic particles are lower during phytoplankton bloom. The concentration of copper is not reduced by the addition of biogenic particles, and its vertical flux is approximately proportional to the total flux, indicating that its concentration in the biogenic particles is nearly equal to that in the non-biogenic particles. The results for nickel and lead show the same tendency as for copper. Cadmium is more concentrated in biogenic particles than in non-biogenic particles, and the concentration of cadmium in the settling particles decreases with depth, similarly to phosphate and organic matter. Thus, metals in seawater are segregated by biological affinities, and the degree of incorporation into biogenic particles is in the order Cd > Pb, Ni, Cu > Co > Mn, Fe, Al. Biogenic particles are the most important agent controlling the vertical distribution of metals in the ocean. They remove the metals from the surface water, transport them through the water column, and regenerate them in the deep.     

Oil well produced water discharges to the North Sea. Part II: comparison of deployed mussels (Mytilus edulis) and the DREAM model to predict ecological risk

Large volumes of water often are produced with oil and gas from offshore platforms. The produced water is separated from the oil and gas and either reinjected into a deep formation or discharged to the ocean. The Norwegian oil and gas industry advocates ecological risk assessment as the basis for managing produced water discharges to the North Sea. In this paper, we compare estimates of ecological risks to water-column communities based on data on hydrocarbon residues in soft tissues of blue mussels deployed for a month near offshore platforms and based on predictions of the Dose related Risk and Effect Assessment Model (DREAM). The study was performed near produced water discharges to the Tampen and Ekofisk Regions of the Norwegian Sector of the North Sea. Because polycyclic aromatic hydrocarbons (PAH) are considered the most important contributors to the ecological hazard posed by produced water discharges, comparisons made here focus on this group of compounds. The mussel approach is based on predicted environmental concentrations (PECs) of individual PAH, estimated from PAH residues in mussels following deployment for a month near several produced water discharges, and predicted no effects concentrations (PNECs) based on a K(ow) regression model. In the DREAM method, PECs for three PAH fractions are estimated in the three-dimensional area around produced water discharge with the DREAM model. PNECs for each fraction are based on the chronic toxicity of a representative PAH from each fraction divided by an assessment factor to account for uncertainty in the chronic value. The mussel method gives much lower estimates of ecological risk than the DREAM method. The differences are caused by the much lower PNECs used in DREAM than derived from the regression model, and by the lower concentrations of aqueous PAH predicted by DREAM than estimated from PAH residues in mussel tissues. However, the two methods rank stations at different distances from produced water discharges in the same order and both identify 2- and 3-ring PAHs as the main contributors to the ecological risk of produced water discharges. Neither method identifies a significant ecological risk of PAH in the upper water column of the oil fields. The DREAM model may produce an overly conservative estimate of ecological risk of produced water discharges to the North Sea.     

溶解有机碳在混合水中的行为研究

研究溶解有机碳(DOC)在海水和黄河水所组成的混合水中的迁移转化行为,结果表明,海水和已过滤黄河水混合时,DOC呈近似的保守性;海水与未过滤的黄河水混合时,DOC呈明显的非保守性。通过研究沉积物对DOC的解吸过程,发现沉积物在盐水中能解吸出DOC,随着盐度的增大,其解吸量也迅速增大。因此可以认为,DOC在河口区的非保守行为是DOC的絮凝和颗粒物的解吸共同作用的结果。     

夏季珠江口沉积物?水界面重金属分布特征及其影响因子研究

珠江口受复杂径?潮动力耦合作用的影响,河口重金属迁移转化机制复杂多变。本文基于2018年夏季珠江口及其邻近海域海水和沉积物的调查资料,研究了珠江口多动力因子驱动下7种重金属元素汞、砷、锌、镉、铅、铜和铬的沉积、迁移和积累机制。结果表明:相比于溶解态重金属（水体中）的赋存状况,吸附态重金属（沉积物中）更稳定,污染也更严重;采用皮尔逊相关分析和主成分分析计算出重金属元素与环境因子之间的响应关系,溶解态重金属主要以稀释混合过程为主,吸附态重金属受有机碳和氧化还原作用的影响较大;沉积物?水界面重金属的分配系数显示出铅和铬易被吸附在颗粒物上,而镉和汞易溶解在水体中,揭示了河口复杂动力影响下元素在不同介质的形态转换特征;除了镉?铬、镉?铜和铬?砷这3组元素间不显著相关,其他元素间的显著相关性表明了重金属元素具有相似的来源,并采用主成分分析探讨了重金属元素的潜在来源,主要来源为工业废水,农业和大气沉降次之。研究结果可为有效控制重金属的排放和河口污染治理提供重要支撑。     

海口湾海水重金属的行为特征

本文对海口湾溶解态铜、铅、锌、镉进行了测定.铜的变化范围为:0.47～1.16μg/dm3,平均值为0.78μg/dm3;铅的变化范围为:0.94～2.36μg/dm3,平均值为1.36μg/dm3;锌的变化范围为:1.28～4.83μg/dm3,平均值为3.14μg/dm3;镉的变化范围为:0.005～0.072μg/dm3,平均值为0.030μg/dm3,Cu、Zn的溶解态含量在龙昆路生活污水排污沟口、秀英工业排污沟口及海甸溪口的测站相对较高,Pb、Cd溶解态含量较低,湾内各站平面分布较为均匀.它们的溶解态含量垂直变化趋势为:Cu、Pb、Zn底层大于表层,而Cd表层大于底层.对Cu、Pb、Zn、Cd的颗粒态含量也进行了测定,指出海口湾海水中的颗粒物对重金属的净化起一定作用.对铜的溶解态中的强络合态和不稳态铜也进行了研究,强络合态占总溶解态的比例均在85%以上,对生物起毒性作用有关的不稳态铜含量很低,均小于5nmol/dm3,表明目前海口湾海水中的重金属铜不会对生物生长产生影响.     

Toxicity of sediments from around a North Sea oil platform: are metals or hydrocarbons responsible for ecological impacts?

Discharges of contaminated drill cuttings have caused appreciable ecological change of the benthos adjacent to many oil and gas platforms in the North Sea. Many platforms have large piles of cuttings lying beneath them and these probably present the greatest potential hazard to the environment during platform decommissioning and removal. There is, however, a lack of consensus on which aspects of drill cuttings are responsible for the adverse ecological effects. This hinders risk assessment of management options. Here we report data on the toxicity of sediments from around the North West Hutton platform to the amphipod Corophium volutator, the polychaete Arenicola marina and the Microtox" acute test system. Sediment was acutely toxic to Corophium out as far as 600 m from the platform. Sediment from 100 m from the platform remained acutely toxic to Corophium when 3% contaminated sediment was mixed with clean sediment. A 10% dilution of this sediment also inhibited Arenicola feeding almost completely. Sediment elutriates did not inhibit Microtox light output, but organics extracted by dichloromethane were very toxic. Fifteen minute EC50 values were as low as 0.25 mg ml(-1) and were strongly correlated with hydrocarbon concentrations. Metal concentrations in whole sediments were correlated with their toxicity to Corophium but the relationship was much weaker when data on dilutions were included. Except at sites immediately adjacent to the platform, metal concentrations were well below ERL values from the literature, so were too low to explain sediment toxicity. Toxicity of sediments to Corophium was closely correlated with their hydrocarbon content, even when tests on dilutions were included in the analysis. We conclude that hydrocarbons are the most significant cause of toxicity in these sediments contaminated with oil based drill cuttings and that polar organics, sulphide. ammonia and other water soluble substances are of much lower significance. Applying OSPAR guidelines to our data on the toxicity of cuttings pile material to Corophium data would give a maximum allowable concentration of 0.03% in clean sediments. The Microtox data indicate that sediments from deeper in the pile would require an even greater dilution than this.     

Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China

Surface water was collected from the Jiulong Estuary for determination of activity concentrations of uranium isotopes in different size fractions, namely, greater than 53, 10 -53, 2 - 10, 0.4 -2 μm, 10 000 u -0.4 μm and less than 10 000 u fractions by microfihration and cross-flow uhrafiltration technologies. Results indicated that most of the dissolved uranium （ 〈 0.4 μm） exis- ted in the low molecular mass fraction （ 〈 10 000 u）, and the colloidal uranium-238 （10 000 u -0.4 μm） only contributed less than 1% of the dissolved uranium-238. The fractions of colloidal uranium in the dissolved phases decreased with the increasing sa- linity. A positive linear relationship between uranium-238 activities and salinities was observed for the dissolved, colloidal and low molecular mass fractions, indicating a conservative behavior of uranium in the Jiulong Estuary. In the particulate phases （ 〉 0.4 μm）, the partitioning of uranium isotopes among different size fractions was controlled by the partitioning of particle concentrations. In the regions with salinities below 20, the partitioning of uranium-238 among different size fractions was as follows： 10 - 53 μm 〉 2 - 10 μm 〉 0.4 - 2 μm greater than above 53 μm. However, the order at the offshore station with salinities above 30 changed as follows ： 0.4 - 2 μm 〉 10 - 53 μm 〉 2 - 10 μm greater than above 53 μm. The fraction of the 0.4 - 2 μm particles increased at the offshore station, suggesting the increased contribution of the authigenic uranium. The activity ratio of uranium-234 to uranium-238 in the dissolved phases, including the low molecular mass fraction and the colloidal fraction, was larger than unity, showing the occurrence of excess uranium-234. In contrast, the activity ratio of uranium-234 to uranium-238 in all size fractions of the particulate phase was close to the equilibrium value （1.0）. The observed different values of the activity ratio of uranium-234 to uranium-238 in the dissolved phase and the partic     

Mechanisms for trace metal enrichment at the surface microlayer in an estuarine salt marsh

The relative contributions of adsorption to particulate surfaces, complexation with surface-active organic ligands and uptake by micro-organisms were evaluated with respect to their importance in the surface microlayer enrichment (‘partitioning’) of Cd, Pb and Cu. The contributions of each process were inferred from field data in which partitioning of the dissolved and particulate forms of Cd, Pb and Cu, total and dissolved organic carbon, particles and total bacteria were observed. In the South San Francisco Bay estuary, particle enrichment appears to control trace metal partitioning. Trace metal association with the particulate phase and the levels of partitioning observed were in the order Pb > Cu > Cd and reflect the calculated equilibrium chemical speciation of these metals in computer-simulated seawater matrices.     

Trace elements in suspended matter from the anoxic hypersaline Tyro and Bannock Basins (eastern Mediterranean)

In the anoxic hypersaline Tyro and Bannock Basins of the eastern Mediterranean, extremely high concentrations of Co (0.015%), Cu (1.35%) and Zn (0.28%) were found in suspended matter collected at the sharp interface between seawater and the anoxic brine. The high particulate Co, Cu and Zn concentrations can be explained by the sharp increase in dissolved sulphide at these interfaces, and the resultant precipitation of metal sulphides. The particulate As, Sb and Mo concentrations also showed a sharp maximum at or close to the interface. However, the contributions of As, Sb and Mo contents in suspended matter to the total concentrations in the water column are small. Scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDAX) of suspended particulate matter from the Tyro Basin revealed spherical particles strongly enriched in Fe, Cu and Zn at the seawater-brine interface.     

威海双岛湾海域重金属的分布特征及生态风险评价

根据2012年双岛湾海域环境调查资料,研究了海水和表层沉积物中重金属的分布特征以及生态风险。结果显示,双岛湾海域海水中的重金属Cu和Pb在湾中部和湾底的部分站位含量较高,Zn和Cr含量在湾底最高、湾外最低,Cd和Hg在湾底和湾外的含量均高于湾中部,As的分布比较均匀;除Zn和Pb外,其余重金属含量均高于周边其他海域。双岛湾海域沉积物中重金属含量较低,与区域背景值相近,其中重金属Hg和Cd在湾内沉积作用明显,而Cu、Pb和Cr在湾外沉积作用比较明显。相关性分析表明,有机碳含量对双岛湾沉积物中的重金属分布影响不大。生态风险评价结果表明,双岛湾海域海水未受到重金属的污染;表层沉积物中重金属存在中低度的生态风险,具有潜在的不利生物毒性效应,重金属毒性大小依次为Pb>As>Cu>Hg>Cr=Cd>Zn。     

The biogeochemistry of some heavy metals and metalloids in the Ob River estuary-Kara Sea section

The biogeochemical behavior of the group of heavy metals and metalloids in the water (including their dissolved and suspended particulate forms), bottom sediments, and zoobenthos was studied in the Ob River estuary-Kara Sea section on the basis of the data obtained during cruise 54 of the R/V Akademik Mstislav Keldysh in September–October 2007. The changes in the ratios of the dissolved and suspended particulate forms of Fe, Mn, Zn, Cu, Pb, Cd, and As were shown, as well as the growth of the fraction of adsorbed forms in the near-bottom suspended particulate matter under the mixing of the riverine and marine waters. The features of the metals’ accumulation in the typical benthic organisms of the Ob River estuary and the Kara Sea were revealed, and their concentrating factors were calculated based on the specific conditions of the environment. It was shown that the shells of the bivalves possessing a higher biomass compared to the other groups of organisms in the Ob River estuary play an important role in the deposition of heavy metals. The mollusks of the Ob River estuary accumulate Cd and Pb at the background level, whereas the Cu and Zn contents appear to be over the background level.     

连云港西大堤海域水环境污染特征分析

连云港拦海西大堤建成已20余年,为得到近几年来本海域水环境中重金属和有机污染物的污染特征,作者于2011年6月对海州湾西大堤海域进行现场调查,根据海洋监测规范对采集水样的DO、COD、石油、重金属(Cu、Zn、Pb、Cd)、活性磷酸盐、无机氮9个化学指标进行测定,并对水质现状进行评价。同时,本研究测定了连云港海州湾西大堤近岸表层沉积物中多种重金属和有机质的含量,利用因子分析法研究了沉积物中重金属的污染来源。结果表明:海州湾西大堤海域海水中重金属Cu、Zn、Pb、Cd的平均质量浓度皆未超出国家二类海水水质标准,石油类和无机氮类污染物为本海域海水中的首要污染物,有机物污染呈现加重的趋势。表层沉积物中重金属Zn、Cd、As的富集指数大于3,属于重污染级别。根据数理统计,发现前3个主成分的贡献率分别为44.09%、27.61%、13.44%,表明沉积物重金属主要有3个来源:工业和生活污水排放、港口煤渣倾倒、海陆交通排污。     

Degradation of phytoplankton-derived organic matter: Implications for carbon and nitrogen biogeochemistry in coastal ecosystems

Experiments were conducted using seawater from the Oregon continental shelf to determine: (1) rates of phytoplankton-derived particulate organic matter (POM) and dissolved organic matter (DOM) degradation by natural microbial communities, and (2) whether inorganic nutrients or flagellate grazing limit the bacterial response to, and subsequent degradation of, the DOM. In the initial seawater samples, nutrients were depleted and organic matter concentrations were elevated above concentrations found in upwelled water, indicative of recent bloom conditions. In whole water treatments incubated for 3 d, an average of 24% of the total organic C and 33% of the POC was degraded, with some portion of the POC being converted to DOC. In treatments incubated after POM was removed by filtration, DOC degradation was initially rapid and then proceeded at a slower rate. After 3 d, an average of 41% of the DOC was degraded. Selective degradation of the C-component of both the POM and DOM relative to the N-component was observed. Reductions in flagellate grazing resulted in increases in bacterial abundance and enhanced DOC degradation, while inorganic nutrient amendments had little effect. Overall, these results suggest that a fraction of the phytoplankton-derived POM and DOM can be rapidly degraded, contributing to oxygen consumption on the continental shelf. The long degradation time of a less labile DOC fraction relative to potential offshelf transport mechanisms suggests that Oregon's coastal waters may be a source of DOC to adjacent offshore waters of the North Pacific.     

中国黄、渤海海水中溶解镉的形态研究

黄、渤海是我国重要的海洋经济渔业开发区域,海水中痕量金属的含量及其存在形态会对海洋环境、海洋渔业产生重要影响。随着近年我国痕量金属采集与分析测试技术的发展,数据的准确性有了新的提升。2016-06—07采集黄、渤海40个站位的海水样品,测定其溶解态金属Cd的总浓度,并应用电化学方法(阳极溶出伏安法)分析Cd存在形态。结果表明,渤海海水中的总溶解态Cd浓度是南黄海海水中的2~3倍,这可能与渤海海水停留时间较长,水深较浅,周边较多河流输入有关。20%~92%以上的溶解态Cd是以有机络合物形态存在,以自由离子态存在的Cd浓度不超过100 pmol/L,低于Cd对浮游生物的毒性阈值。渤海比黄海的金属配体浓度高出2倍以上,高值出现在黄河口周围海域,表明黄河水携带较多有机配体输入。推测我国近海有机配体来源可能包括陆源输入、沉积物再悬浮的解析过程以及藻类分泌。研究还表明,黄、渤海海水中溶解态Cd的有机配体络合常数较其他海域的稍高,这与我国近海废、污水排放的有机络合配体类型有关。