Sediment Parameters of Northwest Black Sea Shelf and Slope: Implications for Transport of Heavy Metals and Radionuclides

In June 1990, sediment cores were obtained from several locations in the Northwest Black Sea shelf and slope by a joint US/USSR scientific team aboard the survey vessel R/V VODYANITSKY. the goal of this investigation was to determine the distribution and levels of radioactivity resulting from the Chernobyl 1986 nuclear accident. the sediment was characterized for texture, mineral composition, redox state, heavy metals, and radionuclides. Correlations emerging from these data reveal paths of dispersal and transport of materials from river sources to deposition sites on the shelf and slope. Kaolinite in the clay mineral suite clearly reflects a dispersal pattern originating in the Danube River and progressing in an easterly direction across the shelf. Sand-size gypsum and the elemental heavy metals Zn, Cu, Cr, and Pb (probable industrial source) as well as the elements Al and Mg (probable terrigenous source) also show a dispersal pattern from the Danube station location in an easterly direction across the shelf. the dispersal direction indicated by these materials is not in conflict with recent existing notions concerning the hydrology of the Northwest Black Sea. Barium anomalies at a midshelf location may be related to operations in the Lebada oil fields situated updrift. Heavy mineral dispersal reflect the Danube and -Crimean Provinces established for the shelf and relate to terrestrial source areas. in addition, the heavy mineral monazite correlates with the radioactive Th 232 found most abundantly in the Crimean Province. Local anomalies of Mn, Fe and U in the sediment at station locations are related to redox (Eh) conditions and other factors. Cs^134/137 data, reported by Curtis and Broadway (1991), correspond to transport and dispersal patterns implicit in the mineralogic, anthropogenic indicators, and sediment characteristics of the study area.     

Preliminary Caesium Data From A Cooperative Us/Ussr Monitoring Survey for Chernobyl Radioactivity in the Black Sea

In June 1990, scientists from the US Environmental Protection Agency's (EPA) Office of Radiation Programs (ORP), and the Woods Hole Oceanographic Institution (WHOI), travelled to Sevastopol in the Soviet Union to work with radioecologists and marine scientists from the USSR Institute of Biology of the Southern Seas (IBSS). the purpose of this cooperative programme was to conduct a monitoring survey for radioactivity in the northwestern Black Sea. Samples of sediment, surface and in-situ water, and biota were collected from fourteen stations for post-survey radionuclide analyses to determine levels of radioactivity in the Black Sea environment resulting from the Chernobyl nuclear power plant explosion and subsequent transport of radioactivity via the Dnepr and Danube rivers. This paper presents the preliminary data for caesium-137 and caesium-134 in sediment samples analyzed by the EPA/ORP. Caesium-137 was measured at four shallow (20-114 m) stations on the shelf near the mouth of the Dnepr and Danube Rivers, but was not detected in sediments from comparable depths at stations further off shore or in slope sediments at depths of 510-1288 meters. Caesium-134 was detected only in sediments from the shallow-water station nearest to the Danube River.     

Preliminary Caesium Data From A Cooperative Us/Ussr Monitoring Survey for Chernobyl Radioactivity in the Black Sea

In June 1990, scientists from the US Environmental Protection Agency's (EPA) Office of Radiation Programs (ORP), and the Woods Hole Oceanographic Institution (WHOI), travelled to Sevastopol in the Soviet Union to work with radioecologists and marine scientists from the USSR Institute of Biology of the Southern Seas (IBSS). the purpose of this cooperative programme was to conduct a monitoring survey for radioactivity in the northwestern Black Sea. Samples of sediment, surface and in-situ water, and biota were collected from fourteen stations for post-survey radionuclide analyses to determine levels of radioactivity in the Black Sea environment resulting from the Chernobyl nuclear power plant explosion and subsequent transport of radioactivity via the Dnepr and Danube rivers. This paper presents the preliminary data for caesium-137 and caesium-134 in sediment samples analyzed by the EPA/ORP. Caesium-137 was measured at four shallow (20–114 m) stations on the shelf near the mouth of the Dnepr and Danube Rivers, but was not detected in sediments from comparable depths at stations further off shore or in slope sediments at depths of 510–1288 meters. Caesium-134 was detected only in sediments from the shallow-water station nearest to the Danube River.     

Enrichments of Trace Metals in Particulate Matter From the Southern East China Sea,North of Taiwan

Abstract

This study investigates the distributions and enrichments of trace metals in suspended and sinking particulate matter from southern East China Sea (ECS) north of Taiwan during the period April 1992 to April 1993. According to these results, concentration of suspended particulate matter in the inner shelf of southern China Sea, the upwellinginfluenced shelf break, and in Kuroshio water are 1.30 (surface)–4.2 (bottom) mg1^?1, ca. 0.4 mg1^?1 and 0.1–0.2 mg1^?1, respectively, reflecting various influences of terrestrial inputs. A benthic nepheloid layer (BNL), apparently owing to resuspension of local and/or remote bottom sediments, formed over the shelf region. Temporal variations in trace metal contents and enrichments in suspended matter from the shelf region reflect the variation of metal inputs from Chinese rivers, particularly from the Changjiang runoff. the enriched metals are more likely to be derived from anthropogenic input, rather than from biological accumulation. in addition, a decrease in metal contents and an increase in salinity confirm the transport of suspended particulate metals from the East China Sea shelf to the open ocean. the feature of metal plume in the intermediate layer (550–800m) of Kuroshio water also verifies this occurrence. Moreover, the sinking particles collected from a sediment trap on the upper slope are relatively enriched in lithogenic matter and trace metals, suggesting the deposit of anthropogenic metals in the slope area.     

Enrichments of Trace Metals in Particulate Matter From the Southern East China Sea, North of Taiwan

This study investigates the distributions and enrichments of trace metals in suspended and sinking particulate matter from southern East China Sea (ECS) north of Taiwan during the period April 1992 to April 1993. According to these results, concentration of suspended particulate matter in the inner shelf of southern China Sea, the upwellinginfluenced shelf break, and in Kuroshio water are 1.30 (surface)-4.2 (bottom) mg1^-1, ca. 0.4 mg1^-1 and 0.1-0.2 mg1^-1, respectively, reflecting various influences of terrestrial inputs. A benthic nepheloid layer (BNL), apparently owing to resuspension of local and/or remote bottom sediments, formed over the shelf region. Temporal variations in trace metal contents and enrichments in suspended matter from the shelf region reflect the variation of metal inputs from Chinese rivers, particularly from the Changjiang runoff. the enriched metals are more likely to be derived from anthropogenic input, rather than from biological accumulation. in addition, a decrease in metal contents and an increase in salinity confirm the transport of suspended particulate metals from the East China Sea shelf to the open ocean. the feature of metal plume in the intermediate layer (550-800m) of Kuroshio water also verifies this occurrence. Moreover, the sinking particles collected from a sediment trap on the upper slope are relatively enriched in lithogenic matter and trace metals, suggesting the deposit of anthropogenic metals in the slope area.     

Behaviour of trace metals in surface sediments of the Black Sea

Early diagenetic processes control the behavior, and more specifically the dissolved‐solid phase distribution of heavy metals in sediments. The depth distribution of Co, Mn, Cu, Zn, Ni, and Fe in sediment were determined in box cores from the Black Sea. The sequential analyses results of these metals indicate contrasting behavior of Mn and Co during early diagenesis, consistent with their respective chemistries and particle‐associations. The profiles of extractable trace metals in the cores are clearly related to sediment type or depositional environment. Topmost sections of the profiles for these elements are generally similar, i.e. rapid decrease in concentration below the sediment surface.     

Spatial Variations of Heavy Metals in the East China Sea Continental Shelf Surface Sediments

Surface sediments collected from continental shelf of the East China Sea were analyzed for heavy metals (iron, manganese, copper, zinc, lead, cadmium), carbonate, organic carbon contents, and grain sizes. the range of concentrations observed were iron: 0.3-1.3 wt%, manganese: 2.3-14 μmole/g, copper: 7.1-184 μmole/g, zinc: 0.16-0.77μmiole/g, lead: 15-98 μmole/g, cadmium: 0.17-3.9 μmole/g, carbonate: 3.6-87 wt%, sand: 10-100%, silt: 0-70% and clay: 0-50%.

A zonal distribution pattern of the heavy metals was found in the East China Sea Continental shelf sediments. High concentrations of most heavy metals, organic carbon and fine-grained sediments were observed in the inner shelf zone, especially those near the discharge of the Yangtze River. Concentrations of these heavy metals decreased from the inner shelf to the shelf break region. High concentrations of metals were also found in sediments near Taiwan. Iron concentrations decreased north-east of the central shelf region. High concentrations of cadmium were found in the shelf break region where biogenic carbonate is predominant. This study showed that biogenic carbonate in the East China Sea shelf break region and the terrigenous sediments from the Yangtze River and island of Taiwan were the major sources of heavy metals. Heavy metal concentrations were strongly influenced by the content of the coarse-grained quartz sand present in the sediments.     

Spatial Variations of Heavy Metals in the East China Sea Continental Shelf Surface Sediments

Surface sediments collected from continental shelf of the East China Sea were analyzed for heavy metals (iron, manganese, copper, zinc, lead, cadmium), carbonate, organic carbon contents, and grain sizes. the range of concentrations observed were iron: 0.3-1.3 wt%, manganese: 2.3-14 μmole/g, copper: 7.1-184 μmole/g, zinc: 0.16-0.77μmiole/g, lead: 15-98 μmole/g, cadmium: 0.17-3.9 μmole/g, carbonate: 3.6-87 wt%, sand: 10-100%, silt: 0-70% and clay: 0-50%.

A zonal distribution pattern of the heavy metals was found in the East China Sea Continental shelf sediments. High concentrations of most heavy metals, organic carbon and fine-grained sediments were observed in the inner shelf zone, especially those near the discharge of the Yangtze River. Concentrations of these heavy metals decreased from the inner shelf to the shelf break region. High concentrations of metals were also found in sediments near Taiwan. Iron concentrations decreased north-east of the central shelf region. High concentrations of cadmium were found in the shelf break region where biogenic carbonate is predominant. This study showed that biogenic carbonate in the East China Sea shelf break region and the terrigenous sediments from the Yangtze River and island of Taiwan were the major sources of heavy metals. Heavy metal concentrations were strongly influenced by the content of the coarse-grained quartz sand present in the sediments.     

碳酸盐岩矿区河流沉积物中重金属的形态特征及潜在生态风险

黔西北土法炼锌及铅锌选矿厂对河流造成严重的重金属污染。河流沉积物中重金属的化学形态研究表明,同一采样点中不同重金属的形态分布和同一重金属在不同采样点中的形态分布均有较大差异。这可能与沉积物组分的不同亲和力,不同河段沉积物中粘土矿物、有机质、Fe Mn氧化物含量的不同以及人为活动(生活污水、选矿剂、矿渣等)的加入等有关,而碳酸盐岩地质背景的河床本身可能也有较大影响。潜在生态危害指数法研究表明,沉积物中重金属表现出强生态风险性,产生生态危害的主要重金属污染物是Pb,其后依次是Cd、Cu和Zn。     

Geochemical index of trace metals in the surficial sediments from the western continental shelf of India, Arabian Sea

The present study focuses on the determination and abundance of trace metals (viz. Cu, Ni, Zn, Cr, Co, Cd, Mn and Fe) in the surficial sediments of west coast of Arabian Sea along the Indian subcontinent. Sediment samples were collected from three transects along the western continental shelf of Arabian Sea. The enrichment of Fe and Mn in coastal oxic-sediments indicates the precipitation of these redox sensitive elements as Fe- and Mn-hydroxides and oxides, whereas the low Fe and Mn concentrations in the oxygen deficient sediments of deeper stations reflects the dissolution of their hydroxides and oxides. Concentrations of fairly redox insensitive trace metals like Cu, Ni, Zn, Cr and Cd (with the exceptions of Cr) showed higher values at nearshore sediments, then it decreased towards seaward and again showed a slight increase at oxygen minimum stations in all the three transects. This geochemical variability in their distributional characteristics is mainly associated with the extent to which the precipitation or dissolution of Fe- and Mn-oxides/hydroxides occur since the scavenging or releasing effects of Fe- and Mn-oxides/hydroxides act as significant ‘sinks’ or ‘sources’ of heavy metals. The change in wind pattern, coastal upwelling and increased productivity are also the reported factors which influence the biogeochemical cycling of trace metals in the surface sediments of west coast of India. Enrichment factor generally showed a high gradient accumulation from nearshore to shelf.