Assessing and managing sediment contamination in transitional waters

Sediment contamination remains a global problem, particularly in transitional waters such as estuaries and coastal lagoons, which are the recipients of chemicals from multiple near- and far-field sources. Although transitional waters are highly productive ecosystems, approaches for assessing and managing their sediment contamination are not as well developed as in marine and fresh waters. Further, although transitional waters remain defined by their variable and unique natural water quality characteristics, particularly salinity, the biota inhabiting such ecosystems, once thought to be defined by Remane's “paradox of brackish water”, are being redefined. The purpose of the present paper is to build on an earlier but now dated (> 12 years old) review of methods to assess sediment contamination in estuaries, extending this to all transitional waters, including information on integrative assessments and on management decision-making. The following are specifically discussed: chemical assessments; bioindicators; biomarkers; and, biological surveys. Assessment and management of sediment contamination in transitional waters need to be focused on ecosystem services and, where appropriate and possible, be proactive rather than reactive when uncertainty has been suitably reduced.     

Plutonium and americium in arctic waters,the North Sea and Scottish and Irish coastal zones

Plutonium and americium have been measured in surface waters of the Greenland and Barents Seas and in the northern North Sea from 1980 through 1984. Measurements in water and biota, Fucus, Mytilus and Patella, were carried out in North-English and Scottish waters in 1982 and Fucus samples were collected from the Irish coast in 1983. Fallout is found to dominate as a source of ^239+240Pu north of latitude 65°N, while for ²³⁸Pu a substantial fraction originates from European nuclear fuel reprocessing facilities. The ²³⁸Pu/^239+240Pu isotope ratio provides clear evidence of the transport of effluent plutonium from the latter to Spitsbergen waters. Fallout plutonium in Arctic waters has a residence time of the order of several years, while for Pu from Sellafield we estimate mean residence times of 11–15 months in Scottish waters and, tentatively, 1·5-3 y during transport from the North Channel (north of the Irish Sea) to Spitsbergen. ²⁴¹Am found in Arctic waters probably originates from the decay of fallout ²⁴¹Pu and, like Pu, tentatively has a residence time of the order of several years. Americium from Sellafield has an estimated mean residence time of 4–6 months in Scottish waters.     

Plutonium and americium inventories in atmospheric fallout and sediment cores from Blelham Tarn, Cumbria (UK)

The objective of this paper is to report on the results of a study of 238Pu, 239 + 240Pu and 241Am inventories onto Blelham Tarn in Cumbria (UK). The atmospheric fallout inventory was obtained by analysing soil cores and the results are in good agreement with the literature: 101 Bq m(-2) for 239 + 240Pu; 4.5 Bq m(-2) for 238Pu and 37 Bq m(-2) for 241Am. The sediment core inventory for the whole lake is compared to the atmospheric fallout inventory. The sediment activity is 60-80% higher than the estimated fallout activity, showing a catchment area contribution and in particular the stream input.     

Plutonium bioaccumulation in seabirds

The aim of the paper was plutonium (²³⁸Pu and ^239+240Pu) determination in seabirds, permanently or temporarily living in northern Poland at the Baltic Sea coast. Together 11 marine birds species were examined: 3 species permanently residing in the southern Baltic, 4 species of wintering birds and 3 species of migrating birds. The obtained results indicated plutonium is non-uniformly distributed in organs and tissues of analyzed seabirds. The highest plutonium content was found in the digestion organs and feathers, the smallest in skin and muscles. The plutonium concentration was lower in analyzed species which feed on fish and much higher in herbivorous species. The main source of plutonium in analyzed marine birds was global atmospheric fallout.     

Plutonium concentrations in waters from the southern Baltic Sea and their distribution in cod (Gadus morhua) skin and gills

The concentrations of (238)Pu and (239+240)Pu in water samples and suspended particulate fractions, as well as in colloidal fraction from the southern Baltic Sea are presented. The (239+240)Pu concentration in surface seawater samples fall within range from 5.2 mBq.m(-3) for Gdańsk Bay to 150 mBq.m(-3) for Pomeranian Bay, most of which (from 52 to 96%) constituted filterable forms (相似文献   

Plutonium isotopes concentration in seawater and bottom sediment off the Pacific coast of Aomori sea area during 1991-2005

A radioactivity survey was launched in 1991 to determine the background levels of ^239+240Pu in the marine environment off a commercial spent nuclear fuel reprocessing plant before full operation of the facility. Particular attention was focused on the ²⁴⁰Pu/²³⁹Pu atom ratio in seawater and bottom sediment to identify the origins of Pu isotopes. The concentration of ^239+240Pu was almost uniform in surface water, decreasing slowly over time. Conversely, the ^239+240Pu concentration varied markedly in the bottom water and was dependent upon the sampling point, with higher concentrations of ^239+240Pu observed in the bottom water sample at sampling points having greater depth. The ²⁴⁰Pu/²³⁹Pu atom ratio in the seawater and sediment samples was higher than that of global fallout Pu, and comparable with the data in the other sea area around Japan which has likely been affected by close-in fallout Pu originating from the Pacific Proving Grounds. The ²⁴⁰Pu/²³⁹Pu atom ratio in bottom sediment samples decreased with sea depth. The land-originated Pu is not considered as the reason of the increasing ^239+240Pu concentration and also decreasing the ²⁴⁰Pu/²³⁹Pu atom ratio with sea depth, and further study is required to clarify it.     

Plutonium isotopes in the Hungarian environment

More than 50 soil samples were analysed from different parts of the country, the activity concentration of 239+240Pu was in the range of 0.01-0.84 Bq/kg dry soil with the average of 0.10 Bq/kg. 238Pu could be detected only in few moss samples and 238Pu/239+240Pu ratio determines the origin of plutonium. 241Pu was determined by liquid scintillation spectrometry. The activity concentration of this isotope in the soil is between 0.04 and 3.74 Bq/kg with the average of 0.82 Bq/kg, while in the moss is also similar 0.01-2.07 Bq/kg fresh mass with the average of 0.43 Bq/kg. Significant difference could not be observed between the different types of soils occurring in the country, but the results could be sorted according to the sampling carried out on undisturbed or cultivated area. The isotope ratios 241Pu/239+240Pu prove that the origin of the plutonium in Hungary is the global fallout determined by the atmospheric nuclear weapon tests.     

Plutonium isotopes in surface air of Prague in 1986-2006

Monitoring of (239,240)Pu in surface air of Prague started in 1986 in connection with the Chernobyl accident. Measurable activities of 10-28muBqm(-3) were found from 29 April 1986 to 5 May 1986. In the most of the monitoring periods of 1987-1996, activities of (239,240)Pu in air were not measurable. Positive values for (239,240)Pu and (238)Pu in air could be obtained after installation of an aerosol sampler with higher flow-rate in 1997. Activity concentrations of (239,240)Pu and (238)Pu in Prague air in the most of quarters of 1997-2006 were in the range 0.53-5.06 and <0.16-1.10nBqm(-3), respectively. Seasonal fluctuations can be found in content of (239,240)Pu in air. Activity ratios of (238)Pu/(239,240)Pu in air are higher than those in top soil, so it can be supposed that (238)Pu is coming to air of Prague also from other sources than resuspension of fallout from atmospheric nuclear tests.     

Plutonium in sheep faeces as an indicator of deposition on vegetation

In order to study the deposition on vegetation of plutonium arising from the testing of nuclear weapons and discharges from nuclear facilities, sheep faeces were collected from the South-west and North of England. The plutonium content of faeces has been shown to be a reproducible and sensitive indicator of deposition on herbage and, with this technique, plutonium discharged from the Sellafield Works of British Nuclear Fuels LImited can be detected 60 km from the site. On moorland pastures the concentration of ^239+240Pu in faeces, expressed as activity per gram of ash, is roughly equal numerically to the deposit of plutonium on 1 m² of vegetation.Some of the plutonium ingested by a grazing sheep is absorbed and the highest concentrations are found in liver. The liver of a sheep grazing on pasture where the ^239+240Pu concentration in faeces was about 2 pCi (74 mBq) g⁻¹ of ash, was found to contain <1% of the Generalised Derived Limit for mutton and offal, and the meat <0·001%.     

Plutonium isotopes in surface air of Prague in 1986–2006

Monitoring of ^239,240Pu in surface air of Prague started in 1986 in connection with the Chernobyl accident. Measurable activities of 10–28 μBq m⁻³ were found from 29 April 1986 to 5 May 1986. In the most of the monitoring periods of 1987–1996, activities of ^239,240Pu in air were not measurable. Positive values for ^239,240Pu and ²³⁸Pu in air could be obtained after installation of an aerosol sampler with higher flow-rate in 1997. Activity concentrations of ^239,240Pu and ²³⁸Pu in Prague air in the most of quarters of 1997–2006 were in the range 0.53–5.06 and <0.16–1.10 nBq m⁻³, respectively. Seasonal fluctuations can be found in content of ^239,240Pu in air. Activity ratios of ²³⁸Pu/^239,240Pu in air are higher than those in top soil, so it can be supposed that ²³⁸Pu is coming to air of Prague also from other sources than resuspension of fallout from atmospheric nuclear tests.     

Plutonium isotopes in the environment: some existing problems and some new ocean results

Marine sediments, terrestrial soils and polar glaciers yield different average values for the ²⁴⁰Pu/²³⁹Pu ratio resulting from the introduction of the actinide to the environment from weapons tests. The average value of the ratio in two sea water profiles from the North Pacific Ocean is 0·23, which is similar to that calculated from Arctic and Antarctic glaciers but differs considerably from the soil-derived average of 0·18. With the exception of near-surface waters, the sea water values of the ²⁴⁰Pu/²³⁹Pu ratio were nearly invariant with depth indicating that plutonium has been homogenized in the water column for a time period of decades. This contrasts with the glacial strata where there were systeamtic changes in the ratio with time of deposition.     

Viruses in surface and drinking waters

Over 114 different human enteric viruses are known. They are all excreted into sewage, and opportunities exist for them to find their way into water distribution systems. The characteristics of the illnesses caused by enteric viruses make their transmission by water difficult to recognize. Methods are not available for isolating all of the enteric viruses from water, so that finding any type of human virus in drinking water is an indication that other types may also be present. With improvements in technology, our laboratory has recently been able to detect group B coxsackieviruses, rotaviruses, and hepatitis A virus in chlorinated drinking water. At present, there are no uniform methods for concentrating, isolating, and identifying viruses in water. Emphasis should be placed on seeking uniformity in methods so that standards can be set for viruses in water.     

Uranium-thorium disequilibrium in north-east Atlantic waters

In this paper we report and compare the concentrations of 234Th and 238U measured in surface and subsurface waters collected in the course of a sampling campaign in the north east Atlantic in June-July 1998. Dissolved 234Th concentrations in surface waters ranged from 5 to 20 Bq m(-3), showing a large deficiency relative to 238U concentrations (typically 42 Bq m-3). This disequilibrium is indicative of active 234Th scavenging from surface waters. Observed 234Th/238U activity ratios, together with corresponding 234Th particulate concentrations, were used to calculate mean residence times for 234Th with respect to scavenging onto particles (tau(diss)) and subsequent removal from surface waters (tau(part)). Residence times in the range 5-30 days were determined for tau(diss) and 4-18 days for tau(part) (n=14). In addition, ultrafiltration experiments at six stations in the course of the same expedition revealed that in north-east Atlantic surface waters a significant fraction (46+/-17%; n=6) of the thorium in the (operationally-defined) dissolved phase (<0.45 microm) is in colloidal form. These observations are consistent with the 'colloidal pumping' model in which it is assumed that 234Th is rapidly absorbed by colloidal particles, which then aggregate, albeit at a slower rate, into larger filterable particles. In essence, colloids act as intermediaries in the transition from the fully dissolved to the filter-retained (>0.45 microm) phase. Thus, the time (tau(c)) for fully dissolved 234Th to appear in the filter-retained fraction is dependent on the rate of colloidal aggregation. Here, we determined tau(c) values in the range 3-17 days.     

Plutonium as a chronomarker in Australian and New Zealand sediments: a comparison with Cs

The construction of high resolution chronologies of sediment profiles corresponding to the last 50-100 years usually entails the measurement of fallout radionuclides ²¹⁰Pb and ¹³⁷Cs. The anthropogenic radionuclide, ¹³⁷Cs, originating from atmospheric nuclear weapons testing can provide an important “first appearance” horizon of known age (1954-1955), providing much-needed validation for the sometimes uncertain interpretations associated with ²¹⁰Pb geochronology. However, while ¹³⁷Cs usually provides a strong signal in sediment in the northern hemisphere, total fallout of ¹³⁷Cs in the southern hemisphere was only 25% that of the north and the low activities of ¹³⁷Cs seen in Australian and New Zealand sediments can make its horizon of first appearance somewhat arguable. Low ¹³⁷Cs fallout also limited the size of the 1963-1964 fallout peak, a peak that is usually seen in northern hemisphere sediment profiles but is often difficult to discern south of the equator.This paper shows examples of the use of nuclear weapons fallout Pu as a chronomarker in sediment cores from Australia (3 sites) and New Zealand (1 site). The Pu profiles of five cores are examined and compared with the corresponding ¹³⁷Cs profiles and ²¹⁰Pb geochronologies. We find that Pu has significant advantages over ¹³⁷Cs, including greater measurement sensitivity using alpha spectrometry and mass spectrometric techniques compared to ¹³⁷Cs measurements by gamma spectrometry. Moreover, Pu provides additional chronomarkers associated with changes in the Pu isotopic composition of fallout during the 1950s and 1960s. In particular, the ²³⁸Pu/^239+240Pu activity ratio shows distinct shifts in the early 1950s and the mid to late 1960s, providing important known-age horizons in southern hemisphere sediments. For estuarine and near-shore sediments Pu sometimes has another significant advantage over ¹³⁷Cs due to its enrichment in bottom sediment relative to ¹³⁷Cs resulting from the more efficient scavenging of dissolved Pu in seawater by sediment particles.     

Viruses on shellfish-growing waters

The conversion of the bivalve shellfish to a virus carriage status is the most important consequence of the virus pollution of shellfish-growing waters. Virus carriage has public health implications of significance for consumers of raw or inadequately cooked shellfish, as well as general biological implications of significance for shellfish themselves. The nonculturable human enteric viruses are responsible for most if not all of the illness transmitted by virus-carrying shellfish. Use of feces-associated natural virus in numbers comparable to those found in grossly polluted waters has been instrumental in developing new perspectives of virus carriage and its biological significance. The feasibility of developing a virus standard for virus surveillance of shellfish and its use for assessment of health risks which aris as a consequence of shellfish virus carriage is discussed.     

Radionuclides in hot mineral spring waters in Jordan

Hot mineral springs in Jordan are very attractive to people who seek physical healing but they are unaware of natural radioactive elements that may be contained in the hot mineral water. The activities of the natural radioactive isotopes were measured and the concentrations of the parents of their natural radioactive series were calculated. The measured radionuclides were 234Th, 226Ra, 214Pb, 214Bi, 228Ac, 228Th, 212Pb, 212Bi and 208Tl. In addition the activities of 235U and 40K were measured. The activities ranged from 0.14 to 34.8 Bq/l, while the concentrations of parent uranium and thorium isotopes ranged from 3.0 x 10(-3) to 0.59 mg/l. The results were compared with those for drinking water.     

Uranium isotopes in Tunisian bottled mineral waters

²³⁴U and ²³⁸U activity concentrations and their relative effective doses have been determined in 10 bottled mineral waters in Tunisia. Alpha spectrometry was used as technique to measure uranium isotopes. The obtained isotopic ratio ²³⁴U/²³⁸U varies between 1.1 and 3 which means that the two isotopes are not in radioactive equilibrium. Measured activity concentration varies between 3.2 and 40 mBq/l for ²³⁴U and between 1.5 and 26.3 mBq/l for ²³⁸U. Effective doses (assuming 2 litres per day of water consumption) coming from this two isotopes are found to vary between 0.16 and 2.02 μSv/a which is lower than the maximum recommended dose level by the WHO.     

Isolation of hydrocarbon-degrading microorganisms in Mediterranean waters

Two species or strains of Penicillium were isolated by the enrichment technique from areas exposed to oil seepage. Infrared spectroscopy revealed that, after eight days of treatment, these microorganisms were capable of degrading paraffinic and aromatic hydrocarbons in media made with Mediterranean waters. They could not, however, degrade crude oil.     

Chemical speciation of metals in sediment elutriates

Surface sediments from two localities in Lake Ontario (Hamilton Harbour and Portsmouth Harbour in Kingston, Ontario) were elutriated with lake water. The distribution of chemical species of metals (Fe, Cu, Ni, Pb, Mn, Cd, and Zn) and nutrients (N and P) was investigated in the elutriates and in the lake water by using the computer program geochem and separation by Chelex 100 resin. The concentration of Mn in the water increased from 10^?6.44M to 10^?5.09M during the elutriation of Lake Ontario sediments. The concentrations of other investigated metals were smaller and different in each of the elutriates. Both methods, the calculations by geochem and the separation by Chelex 100, showed that only Mn was present in the four elutriates as a free ion. However, the chemical speciation of other metals by these two methods was only partially similar. All four sediments released significant quantities of NH₃ which was associated in the elutriates mainly with H. The pH of the lake water decreased from 8.4 to 7.5 during the elutriation.     

Systematic radium survey in spring waters of Slovenia

Radium (226Ra) concentration in 115 Slovenian springs ranged from 7.8 to 43.1 Bq m(-3), well below the current Slovenian limit of 1000 Bq m(-3) for drinking water. It showed two distributions, one grouped at around 24 Bq m(-3) and the other at around 37 Bq m(-3). Contrary to expectation, the level of radium does not always relate to the aquifer type. Only at aquifers and springs composed of acid, intermediate and basic igneous and metamorphic rocks, did radium concentration exceed 36 Bq m(-3) and was below this value at the majority of aquifers composed of carbonate and other sedimentary rocks.