Transfer and distribution of lead in the asteroid Asterias rubens following ingestion of contaminated food: a radiotracer study     

Boisson F  Cotret O  Fowler SW 《Marine pollution bulletin》2002,44(10):1003-1009

A radiotracer technique using 210Pb was applied to quantify the transfer and distribution of lead in the asteroid Asterias rubens following a single ingestion of radio-labelled mussels under controlled laboratory conditions. Approximately 50% of the 210Pb accumulated by mussels in their soft tissues from seawater was transferred to the asteroid through the food pathway resulting in a transfer factor less than unity. Loss kinetics of 210Pb in the asteroid were best described by a two-component exponential model. A. rubens eliminated 56% +/- 5% of the ingested 210Pb in a few days while the remaining fraction (42% +/- 5%), was absorbed and eliminated very slowly. Following ingestion, 210Pb was accumulated in the pyloric caeca and the body wall with little radioisotope found in the coelomic fluid. Lead-210 was then transferred to the organic matrix of the body wall through the general body cavity via the coelomic fluid, and then to the skeleton. In this way, lead appears to be progressively eliminated from the organic matrix of the body wall while it is efficiently trapped in the calcite skeleton. The sequestration and retention of lead in the skeleton is considered as a detoxification process, but it also prevents lead transfer to higher trophic levels of the marine food chain since the skeleton is not digested by higher consumers. In addition, the skeleton of asteroids can be regarded as a bioindicator of long-term dietary lead contamination.  相似文献   

Environment and biology of the Kara Sea: a general view for contamination studies     

Miquel JC 《Marine pollution bulletin》2001,43(1-6):19-27

The recent revelation that over the past 30 years there has been a history of dumping waste including high-level radioactive wastes in the shallow Kara Sea has caused wide-spread concern. The potential impact of these contaminants and other non-nuclear pollutants in the Arctic ecosystem and on human health need to be assessed and, thus, a better insight gained on radioecological processes in cold waters. The present paper proposes a general view on the biology and the environment of the Kara Sea, as a basic tool for the experimental and modelling assessments of the impact of these contaminants.  相似文献   

Water: The conveyor belt for sustainable livelihoods and economic development     

《Physics and Chemistry of the Earth》2016

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EU–Mauritania fisheries partnership in need of more transparency     

《Marine Policy》2014

The new protocol signed in July 2012 by the European Union and Mauritania under the existing Fisheries Partnership Agreement did not produce the expected results. The main component of this protocol consisted of the access rights for 300,000 t/yr of small pelagics. During the first five months after the signature of the protocol, no EU pelagic trawlers used the opportunities created by the protocol. Only after the formal approval of the protocol by the European Council in December 2013, some eastern EU member states started sending their pelagic trawlers back to Mauritania. This resulted in a utilisation of the protocol of 54% for the whole of 2013. Although the EU repeatedly stated that the €70 million/yr paid under the protocol provided good value for money, this assertion was hard to maintain considering the limited utilisation of the agreement. The paper analyses why the EU concluded an agreement with Mauritania that was not wanted by their industry and that was therefore only partially used in the end. It describes the decision making process inside the EU; the different parties involved and their different objectives. It is concluded that the EU decision making process suffers from a lack of transparency and that the combination of a business agreement with development aid resulted in an agreement which did not attain either of the stated objectives. It is proposed that in future the two aspects are clearly separated, and that the development component is extended to other countries in West Africa, including those that have no fish to sell to the EU.  相似文献   

Yield estimation using SPOT-VEGETATION products: A case study of wheat in European countries     

《International Journal of Applied Earth Observation and Geoinformation》2014

In the period 1999–2009 ten-day SPOT-VEGETATION products of the Normalized Difference Vegetation Index (NDVI) and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) at 1 km spatial resolution were used in order to estimate and forecast the wheat yield over Europe. The products were used together with official wheat yield statistics to fine-tune a statistical model for each NUTS2 region, based on the Partial Least Squares Regression (PLSR) method. This method has been chosen to construct the model in the presence of many correlated predictor variables (10-day values of remote sensing indicators) and a limited number of wheat yield observations. The model was run in two different modalities: the “monitoring mode”, which allows for an overall yield assessment at the end of the growing season, and the “forecasting mode”, which provides early and timely yield estimates when the growing season is on-going. Performances of yield estimation at the regional and national level were evaluated using a cross-validation technique against yield statistics and the estimations were compared with those of a reference crop growth model. Models based on either NDVI or FAPAR normalized indicators achieved similar results with a minimal advantage of the model based on the FAPAR product. Best modelling results were obtained for the countries in Central Europe (Poland, North-Eastern Germany) and also Great Britain. By contrast, poor model performances characterize countries as follows: Sweden, Finland, Ireland, Portugal, Romania and Hungary. Country level yield estimates using the PLSR model in the monitoring mode, and those of a reference crop growth model that do not make use of remote sensing information showed comparable accuracies. The largest estimation errors were observed in Portugal, Spain and Finland for both approaches. This convergence may indicate poor reliability of the official yield statistics in these countries.  相似文献   

Dynamics of particle flux and carbon export in the northwestern Mediterranean Sea: A two decade time-series study at the DYFAMED site   总被引：1，自引：0，他引：1  

Juan-Carlos Miquel  Jacobo Martín  Beat Gasser  Alessia Rodriguez-y-Baena  Tarik Toubal  Scott W. Fowler 《Progress in Oceanography》2011,91(4):461-481

The DYFAMED time-series station, located in the open Ligurian Sea, is one of the few pluriannual flux programs in the world and the longest in the Mediterranean Sea. The trap data series is one of only three multi-decadal data sets in existence, and it provides flux information for an environment that is distinct from the other long-term data sets. At DYFAMED, downward fluxes of particles, carbon and other major elements have been regularly measured with sediment traps since 1986 at fixed depths of 200 and 1000 m. An overview is presented of the main trends of particle and carbon fluxes observed during the period 1988–2005, period when the mooring was located on the northern side of the Ligurian Sea. In spite of considerable interannual variability, fluxes displayed a marked seasonal pattern with the highest fluxes occurring during winter and spring and lowest fluxes throughout the stratified season (summer–autumn). Organic carbon fluxes measured at both depths were highly variable over time, ranging from 0.3 to 59.9 (mean 6.8) mg C m⁻² d⁻¹ at 200 m, and from 0.2 to 37.1 (mean 4.3) mg C m⁻² d⁻¹ at 1000 m. Mass fluxes were maximal in winter, whereas carbon fluxes were maximal in late spring. Reasonably good agreement existed between particle fluxes at both depths over the years, indicating a relatively efficient and rapid transport of particles from the upper ocean to the deep sea. However, during certain periods mass flux increased with depth suggesting lateral inputs of particles that by-pass the upper trap. Since 1999, the system has apparently shifted towards an increasing occurrence of extreme flux events in response to more vigorous mixing of the water column during the winter months. Although annual mass fluxes have increased in the last years, mean POC fluxes have not substantially changed over time, due mainly to lower carbon contents of the sinking particles during maxima of mass flux.  相似文献   

Stable isotopic composition of precipitation in the River Bhagirathi Basin and identification of source vapour     

S. P. Rai  P. Purushothaman  B. Kumar  Noble Jacob  Y. S. Rawat 《Environmental Earth Sciences》2014,71(11):4835-4847

River Ganges one of important rivers in the northern part of India receives water from two of its tributaries, Alaknanda and Bhagirathi. In this present study, we have tried to characterise the precipitation in the Bhagirathi River Basin. The study shows that isotopic composition of precipitation shows depleted nature during monsoon period due to moisture source from the oceanic region and from African region of Indian Ocean and enriched isotopic composition during non-monsoon period due to moisture source from westerlies and local evaporation. The study also shows that temperature and amount show expected positive and negative relationship with individual locations. A positive relationship is exhibited by amount for the entire region due to depleted isotopic composition with increase in altitude. The altitude effect shows that there is a depletion of up to ?0.24 to ?0.29 ‰ of isotopic composition with an increase in 100 m of elevation.  相似文献   

Impact of recharge variations on water quality as indicated by excess air in groundwater of the Kalahari, Botswana     

Karsten Osenbrück  Jürgen Sültenfuß  Stephan M. Weise 《Geochimica et cosmochimica acta》2009,73(4):911-289

Groundwater is an important and often exclusive water resource in arid and semi-arid regions. The aim of the present paper was to gain insight into the processes and conditions that control the deterioration of groundwater quality in the semi-arid Kalahari of Botswana. Measurements of ³He, ⁴He, ²⁰Ne, ²²Ne, and of ¹⁴C of dissolved inorganic carbon (DIC) were combined with existing isotopic and hydrochemical data to investigate groundwater from the Ntane Sandstone Aquifer, which is affected by high nitrate concentrations of non-anthropogenic origin. All groundwater samples revealed neon concentrations in excess to air-saturated water, which we attributed to the addition of excess air during recharge. Neon concentrations ranged from values close to air saturation for ¹⁴C DIC rich samples (up to 80.5%MC) up to values of 90% in excess to air-saturated water for lower ¹⁴C DIC contents (2.6-61.3%MC). A strong linear correlation of excess Ne with nitrate concentrations suggests an intimate connection between groundwater quality and the processes and conditions during groundwater recharge. Low groundwater recharge rates under present-day semi-arid conditions are associated with low amounts of excess Ne and elevated nitrate concentrations. In contrast to this, higher excess Ne values in groundwater of lower ¹⁴C DIC and nitrate contents indicate that the high quality groundwater end-member presumably is related to higher groundwater table fluctuations during wetter climatic conditions in the past. We attribute the decline in groundwater quality with respect to nitrate to a decreasing rate and temporal variability of groundwater recharge, and to concurrent changes in biogeochemical activities following a transition to a drier climate during the Holocene. Under such conditions, a much stronger decrease in groundwater recharge compared to the release of nitrate from soil organic matter may result in elevated nitrate concentrations in the vadose zone and groundwater. This implies a strong impact of climate change on the transport of solutes like nitrate through the vadose zone which needs to be considered in predictions of future groundwater quality.  相似文献   

Hydrogeochemical evaluation and statistical analysis of groundwater of Sylhet,north-eastern Bangladesh     

Ahmed  Nasir  Bodrud-Doza  Md.  Islam  S. M. Didar-Ul  Choudhry  Manzoor Ahmad  Muhib  Md. Iftakharul  Zahid  Anwar  Hossain  Shahadat  Moniruzzaman  Md.  Deb  Nipa  Bhuiyan  Md. Abdul Quaiyum 《中国地球化学学报》2019,38(3):440-455

Acta Geochimica - To investigate the hydrogeochemical characteristics of groundwater 23 shallow, 30 intermediate and 38 deep wells samples were collected from Sylhet district of Bangladesh, and...  相似文献   

Organochlorine contamination (PCBs, DDTs, HCB, HCHs) in sediments from Cienfuegos bay, Cuba   总被引：1，自引：0，他引：1  

I. Tolosa  M. Mesa-Albernas 《Marine pollution bulletin》2010,60(9):1619-1624

The spatial distribution of various organochlorinated compounds, e.g. PCBs, DDTs, HCB and HCHs, were investigated in sediments from Cienfuegos bay, Cuba. Their concentrations appeared to be relatively low by global standards and only sediments receiving the impact from the residual waters of the city and thermoelectrical power approached the sediment quality guidelines for PCBs and DDTs. Relatively higher ΣDDT concentrations and high DDT/DDE + DDD ratios in two sites near the outfalls of the city indicated a current DDT usage, probably linked to public health emergencies. These results contribute to the sparse regional database for organochlorinated compounds in the Caribbean marine environment.  相似文献