Release of particles and metals into seawater following sediment resuspension of a coastal mine tailings disposal off Portmán Bay,Southern Spain

Environmental Science and Pollution Research - Portmán Bay in Southern Spain is one of the most extreme cases in Europe of anthropogenic impact on the marine ecosystem by the disposal of mine...     

210Pb as a dietary indicator in the Antarctic pelagic community

The naturally occurring radionuclide ²¹⁰Po is useful as a tracer of diets of marine organisms. Data for ²¹⁰Pb, the grandparent of ²¹⁰Po, are less abundant: we therefore report here ²¹⁰Pb concentrations in a substantial collection of marine biota obtained from the Antarctic Ocean during the SIBEX II cruise in 1985. The general levels of ²¹⁰Pb are within the range of previously published data but, as in the case of ²¹⁰Po, there are differences which can be associated with variations in the diet of the organism. The levels of ²¹⁰Pb in the krill Euphausia superba show seasonal changes which can be interpreted in terms of changing diet. In a simple classification of the pelagic food chain, the levels of ²¹⁰Pb tend to increase from omnivores to filter-feeders to predators.     

Sorption-desorption tests to assess the risk derived from metal contamination in mineral and organic soils

We obtained the sorption isotherms of Cd, Cu, Pb and Zn from seven soils with contrasting properties, including mineral and organic soils. The distribution coefficients (Kd) were determined from batch tests in a solution that simulated the soil solution cationic composition. The Kd values of the target metals varied greatly depending on soil type and initial metal concentration. Sorption isotherms were fitted to Freundlich and Langmuir models, and derived parameters were correlated to soil properties through the construction of a correlation matrix and application of Principal Component Analysis. The batch Kd showed a satisfactory agreement with the Kd obtained from field-contaminated soils. The sorption tests were complemented with the estimation of the reversibility of metal sorption by the application of an extraction test. The extraction yields, which did not relate to the initial metal concentration, depended on the metal-soil combination, and showed no correlation to batch Kd values. The risk derived from a contamination event was estimated through the quantification of a Retention Factor, defined as the ratio of the Kd versus the extraction yield. Results showed that this was an excellent index to highlight which metal and soil represent the most vulnerable scenarios after a contamination event.     

Surfactants in sludge-amended agricultural soils: a review

Surfactants are included in different detergent formulations and are one of the most ubiquitous and important families of organic compounds. Although the generic term applies to a great number of products, 80% of their demand is covered by only ten types of compounds. The global surfactant market volume size is more than 18 million tons per year. Large quantities of surfactants are continuously released into the environment, where they can or cannot be degraded depending on their structure. The alkylbenzenesulphonate (LAS) is the most widely used surfactant. LAS can be degraded under aerobic conditions but is persistent in the environment under anaerobic conditions. Surfactants may enter the terrestrial environment through several routes, with the use of sewage sludge as fertiliser on agricultural land being by far the most important. High concentrations of surfactants and their degradation products may affect the biota. On the other hand, due to their amphiphilic nature, surfactants may interact both with inorganic as well as organic contaminants affecting their bioavailability.     

Extension of sensitivity and uncertainty analysis for long term dose assessment of high level nuclear waste disposal sites to uncertainties in the human behaviour

Biosphere dose conversion factors are computed for the French high-level geological waste disposal concept and to illustrate the combined probabilistic and deterministic approach. Both ¹³⁵Cs and ⁷⁹Se are used as examples. Probabilistic analyses of the system considering all parameters, as well as physical and societal parameters independently, allow quantification of their mutual impact on overall uncertainty. As physical parameter uncertainties decreased, for example with the availability of further experimental and field data, the societal uncertainties, which are less easily constrained, particularly for the long term, become more and more significant. One also has to distinguish uncertainties impacting the low dose portion of a distribution from those impacting the high dose range, the latter having logically a greater impact in an assessment situation. The use of cumulative probability curves allows us to quantify probability variations as a function of the dose estimate, with the ratio of the probability variation (slope of the curve) indicative of uncertainties of different radionuclides. In the case of ¹³⁵Cs with better constrained physical parameters, the uncertainty in human behaviour is more significant, even in the high dose range, where they increase the probability of higher doses. For both radionuclides, uncertainties impact more strongly in the intermediate than in the high dose range. In an assessment context, the focus will be on probabilities of higher dose values. The probabilistic approach can furthermore be used to construct critical groups based on a predefined probability level and to ensure that critical groups cover the expected range of uncertainty.     

Correcting serum concentrations of organochlorine compounds by lipids: Alternatives to the organochlorine/total lipids ratio

IntroductionWhen studying the effects of organochlorine compounds (OCs) on human health it is common to correct serum concentrations of OC by total lipids (TL). However, the relationship between serum OCs and serum TL is far from established in many diseases, including several cancers. Our aim was to analyze the relationship between serum OC and TL in patients with pancreatic ductal adenocarcinoma (PDA), and to explore several alternatives to perform the OC lipid correction.MethodsIncident cases of PDA were interviewed and had blood drawn soon around hospital admission (n = 144). Serum concentrations of OCs were analysed by high-resolution gas chromatography with electron-capture detection.ResultsMost patients with high TL had moderate or low concentrations of OCs. By contrast, the variability of OC values among patients with normal TL was large. Correlations were of a similar magnitude between OC and TL and between OC and total cholesterol; while these correlations were weak (all Spearman's ρ < 0.3 and R² < 0.11), no OC were significantly correlated with triglycerides. Although all alternatives to the OC/TL linear ratio were statistically significant for at least one OC, their R² was always below 10%.ConclusionsIn patients with severe diseases as PDA, linear correction of OC by TL as commonly performed in epidemiologic studies may be inappropriate. Results contribute to the scant literature on the rationale to correct serum concentrations of OC by lipids. They suggest that it is unwarranted to routinely correct OC by TL, offer ways to assess such need, and present alternatives as no TL correction, correction by total cholesterol only or use of different statistical models.     

Eutrophic urban ponds suffer from cyanobacterial blooms: Dutch examples

Ponds play an important role in urban areas. However, cyanobacterial blooms counteract the societal need for a good water quality and pose serious health risks for citizens and pets. To provide insight into the extent and possible causes of cyanobacterial problems in urban ponds, we conducted a survey on cyanobacterial blooms and studied three ponds in detail. Among 3,500 urban ponds in the urbanized Dutch province of North Brabant, 125 showed cyanobacterial blooms in the period 2009–2012. This covered 79 % of all locations registered for cyanobacterial blooms, despite the fact that urban ponds comprise only 11 % of the area of surface water in North Brabant. Dominant bloom-forming genera in urban ponds were Microcystis, Anabaena and Planktothrix. In the three ponds selected for further study, the microcystin concentration of the water peaked at 77 μg l^?1 and in scums at 64,000 μg l^?1, which is considered highly toxic. Microcystin-RR and microcystin-LR were the most prevalent variants in these waters and in scums. Cyanobacterial chlorophyll-a peaked in August with concentrations up to 962 μg l^?1 outside of scums. The ponds were highly eutrophic with mean total phosphorus concentrations between 0.16 and 0.44 mg l^?1, and the sediments were rich in potential releasable phosphorus. High fish stocks dominated by carp lead to bioturbation, which also favours blooms. As urban ponds in North Brabant, and likely in other regions, regularly suffer from cyanobacterial blooms and citizens may easily have contact with the water and may ingest cyanobacterial material during recreational activities, particularly swimming, control of health risk is of importance. Monitoring of cyanobacteria and cyanobacterial toxins in urban ponds is a first step to control health risks. Mitigation strategies should focus on external sources of eutrophication and consider the effect of sediment P release and bioturbation by fish.     

Trophic impact, metabolism, and biogeochemical role of the marine cladoceran Penilia avirostris and the co-dominant copepod Oithona nana in NW Mediterranean coastal waters

In this work we studied the trophic ecology and feeding impact of the cladoceran Penilia avirostris and the cyclopoid copepod Oithona nana, the two dominant zooplankters in the summer communities of the coastal NW Mediterranean, on the naturally occurring microbial communities. In order to ascertain carbon surplus for growth and reproduction and the contribution to carbon and nitrogen recycling of these two species, we also determined their basal metabolism and excretion rates. The experiments conducted during summers 2002, 2003, and 2004 indicate that P. avirostris grazed mostly upon small flagellates, dinoflagellates, and diatoms, whereas O. nana had a narrower prey range, selecting motile organisms such as ciliates and occasionally dinoflagellates. The grazing impact of both species accounted, on average, for <10% of the standing stock of the microbial groups considered. In spite of the oligotrophic conditions, the feeding activity of P. avirostris is in general sufficient to compensate basal metabolism and allows a surplus for growth and reproduction. This was not the case for O. nana, its daily rations being often lower than the carbon basal demands. Regarding excretion rates, both species presented different N:P excretion ratios, the ones of O. nana falling within values typical for copepods, whereas the absence of detectable phosphorus excretion by P. avirostris implied an unbalance recycling with respect to typical Redfield ratio composition of marine seston.