Inter- and intra-species variation in acute zinc tolerance of field-collected cladoceran populations

Acute zinc toxicity was assessed for 10 freshwater cladoceran species collected in six different ecosystems across Europe and for two standard laboratory-reared species (Daphnia magna and Ceriodaphnia dubia). The collected organisms belonged to five different genera: Daphnia (subgenus Daphnia and Ctenodaphnia), Ceriodaphnia, Simocephalus, Acroperus and Chydorus. The 48-h EC50 of the field-collected organisms tested in standard laboratory water ranged from 375+/-141 to 4314+/-1513 microg Znl(-1). The laboratory clone of D. magna was less sensitive than the majority of the field-collected species, while our laboratory Ceriodaphnia dubia was the second most sensitive. Considerable inter-species variation was found within the genus of Ceriodaphnia (factor 6) and within the genus Daphnia (factor 8). Among the different (sub)genera tested, Chydorus and Ctenodaphnia were significantly more tolerant than the others (up to a factor 3 difference). A significant positive relationship (r2=0.67, p<0.05) between the mean cladoceran 48-h EC50 and the ambient zinc concentration of the different aquatic systems was demonstrated, suggesting a role of acclimation and/or adaptation. No significant correlation between the acute zinc tolerance and the length of the organisms was found.     

Earthworm biomass as additional information for risk assessment of heavy metal biomagnification: a case study for dredged sediment-derived soils and polluted floodplain soils

The important role of earthworms in the biomagnification of heavy metals in terrestrial ecosystems is widely recognised. Differences in earthworm biomass between sites is mostly not accounted for in ecological risk assessment. These differences may be large depending on soil properties and pollution status. A survey of earthworm biomass and colonisation rate was carried out on dredged sediment-derived soils (DSDS). Results were compared with observations for the surrounding alluvial plains. Mainly grain size distribution and time since disposal determined earthworm biomass on DSDS, while soil pollution status of the DSDS was of lesser importance. Highest earthworm biomass was observed on sandy loam DSDS disposed at least 40 years ago.     

Individual PCBs as predictors for concentrations of non and mono-ortho PCBs in human milk

32 Dutch human milk samples were analyzed for PCBs with either HRGC-ECD or HRGC-LRMS in the NCI mode. Samples were collected from three different locations in The Netherlands: Amsterdam, Rotterdam and Groningen. Quantitatively, no differences could be observed between the three localities, while in addition the congener specific pattern showed a striking similarity for all individual samples. Only principal component analysis revealed slight individual differences. Based on similarities in the PCB profiles, linear relationships were calculated between 2,3′4,4′,5-PnCB (#118) or 2,2′4,4′5,5′HxCB (#153) and the most relevantnon andmonoortho PCBs exhibiting dioxinlike activity. These PCBs included 2,3,3′,4,4′-PnCB (#105), 3,3′,4,4′5-PnCB (#126) 2,3,3′,4,4′,5-HxCB (#156), 2,3,3′,4,4′,5′-HxCB (#157), 2,3′,4,4′,5,5′-HxCB (#167) and 3,3′,4,4′,5′5-HxCB (#169). Good linear relationships were observed between individual PCBs. Based on the results of this study, PCB #118 can be used to predict concentrations of the PCBs #105 and #126. PCB #153 can be used as a predictor for the PCBs #156, #157, #167 and #169, but also for the total toxic equivalencies (TEQs) ofnon andmonoortho PCBs present in human milk. This method using certain PCBs as predictors for other toxicological relevant congeners, can be useful and cost effective, e.g. for epidemiological studies. However, before applied a number of conditions should be met. These are:

1. A stable composition of the PCB matrix should be established.
2. A possible time dependent change in composition of the matrix should first be excluded when used over different time periods.

     

Copper regulation and homeostasis of Daphnia magna and Pseudokirchneriella subcapitata: influence of acclimation

This study aimed to evaluate (1) the capacity of the green alga Pseudokirchneriella subcapitata and the waterflea Daphnia magna to regulate copper when exposed to environmentally realistic copper concentrations and (2) the influence of multi-generation acclimation to these copper concentrations on copper bioaccumulation and homeostasis. Based on bioconcentration factors, active copper regulation was observed in algae up to 5 microg Cu L(-1) and in daphnids up to 35 mug Cu L(-1). Constant body copper concentrations (13+/-4 microg Cu g DW(-1)) were observed in algae exposed to 1 through 5 microg Cu L(-1) and in daphnids exposed to 1 through 12 microg Cu L(-1). At higher exposure concentrations, there was an increase in internal body copper concentration, while no increase was observed in bioconcentration factors, suggesting the presence of a storage mechanism. At copper concentrations of 100 microg Cu L(-1) (P. subcapitata) and 150 microg Cu L(-1) (D. magna), the significant increases observed in body copper concentrations and in bioconcentration factors may be related to a failure of this regulation mechanism. For both organisms, internal body copper concentrations lower than 13 microg Cu g DW(-1) may result in copper deficiency. For P. subcapitata acclimated to 0.5 and 100 microg Cu L(-1), body copper concentrations ranged (mean+/-standard deviation) between 5+/-2 microg Cu g DW(-1) and 1300+/-197 microg Cu g DW(-1), respectively. For D. magna, this value ranged between 9+/-2 microg Cu g DW(-1) and 175+/-17 microg Cu g DW(-1) for daphnids acclimated to 0.5 and 150 microg Cu L(-1). Multi-generation acclimation to copper concentrations >or =12 microg Cu L(-1) resulted in a decrease (up to 40%) in body copper concentrations for both organisms compared to the body copper concentration of the first generation. It can be concluded that there is an indication that P. subcapitata and D. magna can regulate their whole body copper concentration to maintain copper homeostasis within their optimal copper range and acclimation enhances these mechanisms.     

Quantitative Pollution Spill Risk Assessment: Using A Gis-Based System

Federal and State agencies have recently advocated risk-based analysis as a mechanism for advancing regulatory reform and safety determination in marine systems. the present investigation promotes this objective through the development of risk-based environmental planning strategies for oil spill contingency plans. This alternative approach to contingency planning departs from conventional methodology by employing quantitative risk assessment methods to identify hazardous oil spill zones and sensitive environmental areas, R_o and R_e respectively. the product of this conversion is referenced on a single “Risk” layer within a Geographic Information System (GIS) framework allowing coastal managers to evaluate natural resource data with associated elements of oil spill risk. As a new tool for coastal pollution management, risk-based environmental planning strategies have shown potential for evolving more efficient oil spill contingency plans.     

Plastic waste as a valuable resource: strategy to remove heavy metals from wastewater in bench scale application

Environmental Science and Pollution Research - Single-use plastic waste is gradually considered a potential material for circular economy. Ion exchange resin obtained from polystyrene waste by...     

Avian herbivory: an experiment, a field test, and an allometric comparison with mammals

Mechanistic studies on herbivore functional responses have largely taken place in mammals; very little has been done in herbivorous birds so far. Here we aim to fill that gap by experimentally quantifying the (short-term) functional response of a large avian herbivore, the Bewick's Swan (Cygnus columbianus bewickii). We explicitly distinguish between encounter-limited and handling-limited foraging by analyzing the results in the framework of the models of D. E. Spalinger and N. T. Hobbs, originally developed for mammalian herbivory. Bite size in captive swans was experimentally manipulated by varying sward height. The time interval between two bites increased with bite size, which supports the handling-limited model (process 3) and rejects the encounter-limited models (processes 1 and 2). Subsequently, we took the obtained functional response parameters into the field in order to predict, from measurements of sward height, (1) bite sizes, (2) handling times, and (3) short-term intake rates in free-ranging swans. Indeed, for all three variables, the observed values closely matched the experimentally based predictions. Finally, we review functional response parameters available in the literature on avian herbivores and scale them allometrically in relation to mammals. This analysis revealed that maximum bite sizes, and therefore maximum intake rates, in herbivorous birds are smaller than in herbivorous mammals. We hypothesize and provide evidence that birds compensate by longer daily foraging times.     

Day-of-week patterns of particulate matter and its chemical components at selected sites in California

This paper analyzes day-of-week variations in concentrations of particulate matter (PM) in California. Because volatile organic compounds (VOCs) and oxides of nitrogen (NOx) are not only precursors of ozone (O3) but also of secondary PM, it is useful to know whether the variations by day of week in these precursors are also evident in PM data. Concentrations of PM < or = 10 microm (PM10) and < or = 2.5 microm in aerodynamic diameter (PM2.5) were analyzed. PM concentrations exhibit a general weekly pattern, with the maximum occurring late in the workweek and the minimum occurring on weekends (especially Sunday); however, this pattern does not prevail at all sites and areas. PM nitrate (NO3-) data from Size Selective Inlet (SSI) samplers in the South Coast Air Basin (SoCAB) tend to be somewhat lower on weekends compared with weekdays. During 1988-1991, the weekend average was lower than the weekday average at 8 of 13 locations, with an average decrease of 1%. During 1997-2000, the weekend average was lower than the weekday average at 10 of 13 locations, with an average decrease of 6%. The weekend averages are generally lower than weekday averages for sulfates, organic carbon, and elemental carbon. Because heavy-duty trucks typically represent a major source of elemental carbon, the weekend decrease in heavy-duty truck traffic may also result in a decrease in ambient elemental carbon concentrations.     

Porewater chemistry in compacted re-saturated MX-80 bentonite

Bentonites of various types are being investigated in many countries as backfill materials in high-level radioactive waste disposal concepts. Being able to understand the chemistry of the porewater in compacted bentonite is very important since it is critical to predicting radionuclide solubilities and to the synthesis of sorption data bases, and hence to repository safety studies. In this paper, porewater compositions in compacted bentonites are calculated, taking into consideration such factors as montmorillonite swelling, semi-permeable membrane effects, very low "free water" volumes, and the highly effective buffering characteristics of the exchangeable cations and the amphoteric edge sites. The former buffer the cation concentrations and the latter fix the pH in the porewater of a re-saturated bentonite. The above considerations are used in conjunction with previously measured physico-chemical characterisation data on MX-80 powder to calculate porewater compositions in compacted bentonites. For the MX-80 material specified, the porewaters calculated for initial dry densities between 1200 and 1600 kg m(-3) had relatively high ionic strengths (I approximately 0.3 M), similar cation concentrations and a pH equal to 8.0. The porewaters changed from being Na(2)SO(4)-rich at 1200 kg m(-3) to a NaCl/Na(2)SO(4) type water at 1600 kg m(-3).