The success of elutriate tests in extended prediction of water quality after a dredging operation under freshwater and saline conditions

Dredging simulation by elutriate tests accurately predicted concentrations of Hg, Cu, Mn and Fe released to the water column from contaminated sediment to within 1 order of magnitude. Hg and Cu concentrations increased by up to 7-fold after dredging, but declined to background concentrations within 48 h. Maximum loadings of Hg and Cu coincided with Fe and total organic carbon (TOC) water column concentrations, suggesting Hg and Cu are adsorbed onto particulates of Fe oxides and organic material. Seasonal changes in redox potential and temperature did not significantly affect metal release from sediments. Saline water did not cause significant increases in contaminant release from sediments to the water column over that observed for freshwater. Water quality standards of 1 µg l^–1 Hg and 28 µg l^–1 Cu as annual averages were not breached by dredging operations. Long-term effects of dredging on Hg and Cu availability, due to deposition of contaminated material as surficial sediments, is, however, of concern.     

Genetic diversity and structure in Pelvetia fastigiata (Phaeophyta: Fucales): does a small effective neighborhood size explain fine-scale genetic structure?

We investigated the genetic diversity and genetic structure of southern California populations of the common intertidal fucoid seaweed Pelvetia fastigiata, (J. Ag.) De Toni by means of allozyme electrophoresis and estimates of genetic neighborhood area and size, which are the first for seaweeds. We predicted that P. fastigiata populations would exhibit relatively low genetic diversity and high genetic structure because the seaweed is monoecious and has limited dispersal of gametes and zygotes. This prediction was supported; genetic diversity indices were all low compared to other seaweeds studied, but high genetic structure was evident particularly within individual reefs. Geospatial statistical analyses (second-order analyses) revealed clustered distribution of glucose-6-phosphate isomerase (GPI) alleles at the scale of 1 to 6 m within three reefs. The rare alleles were distributed only at the landward third of the reefs. Genetic neighborhood area (2.3 m²) and size (133 individuals) were estimated from parent-offspring dispersal distributions of gametes and zygotes from attached thalli and also detached reproductive fragments, which contributed very little to the effective neighborhood size. The neighborhood size was in the small theoretical range in which genetic drift could be responsible for the within-reef genetic structure. This result was equivocal, because the stereotyped distribution of rare alleles on the tips of each reef was highly unlikely to be due to random events (6.9×10^-24). These results emphasize (1) the importance of allele mapping in addition to spatial statistics to elucidate genetic structure, and (2) that interpretation of genetic-structure statistics as evidence for gene flow can be complicated, even when supported with independent estimates of gene flow, if data are lacking on selection and sporadic migration events. The emerging pattern of low levels of polymorphisms in brown seaweeds will limit the use of Wright's F-statistics and will require alternative, more direct techniques for the analysis of mechanisms responsible for population genetic structure.     

ICT reuse in socio-economic enterprises

In Europe, socio-economic enterprises such as charities, voluntary organisations and not-for-profit companies are involved in the repair, refurbishment and reuse of various products. This paper characterises and analyses the operations of socio-economic enterprises that are involved in the reuse of Information and Communication Technology (ICT) equipment. Using findings from a survey, the paper specifically analyses the reuse activities of socio-economic enterprises in the UK from which Europe-wide conclusions are drawn. The amount of ICT products handled by the reuse organisations is quantified and potential barriers and opportunities to their operations are analysed. By-products from reuse activities are discussed and recommendations to improve reuse activities are provided. The most common ICT products dealt with by socio-economic enterprises are computers and related equipment. In the UK in 2010, an estimated 143,750 appliances were reused. However, due to limitations in data, it is difficult to compare this number to the amount of new appliances that entered the UK market or the amount of waste electrical and electronic equipment generated in the same period. Difficulties in marketing products and numerous legislative requirements are the most common barriers to reuse operations. Despite various constraints, it is clear that organisations involved in reuse of ICT could contribute significantly to resource efficiency and a circular economy. It is suggested that clustering of their operations into “reuse parks” would enhance both their profile and their products. Reuse parks would also improve consumer confidence in and subsequently sales of the products. Further, it is advocated that industrial networking opportunities for the exchange of by-products resulting from the organisations’ activities should be investigated. The findings make two significant contributions to the current literature. One, they provide a detailed insight into the reuse operations of socio-economic enterprises. Previously unavailable data has been presented and analysed. Secondly, new evidence about the by-products/materials resulting from socio-economic enterprises’ reuse activities has been obtained. These contributions add substantially to our understanding of the important role of reuse organisations.     

Biodegradation of acrylic acid polymers and oligomers by mixed microbial communities in activated sludge

The biodegradability (mineralization to carbon dioxide) of acrylic acid oligomers and polymers was studied in activated sludge obtained from continuous-flow activated sludge (CAS) systems exposed to mixtures of low molecular weight (Mw < 8000) poly(acrylic acid)s and other watesoluble polymers [poly(ethylene glycol)s] in influent wastewater. Dilute preparations of activated sludge from the CAS units were tested for their ability to mineralize acrylic acid monomer and dimer, as well as a series of model acrylic acid oligomers and polymers (Mw 500, 700, 1000, 2000, and 4500), as sole carbon and energy sources. Complete mineralization of acrylic acid monomer and dimer was observed in low-biomass sludge preparations previously exposed to the polymer mixture, based on carbon dioxide production and residual dissolved organic carbon analyses. Extensive (though incomplete) degradation was also observed for the low molecular weight acrylic acid oligomers (Mw 500 and 700), but degradation dropped off sharply for the 1000, 2000, and 4500 Mw polymers. Radiochemical (¹⁴C) data also confirmed the low degradation potential of the 1000, 2000, and 4500 Mw materials. Degradation of two commercial poly(ethylene glycol)s at 1000 and 3400 Mw was complete and comparable to that of the acrylic acid monomer and dimer. Our results indicate that mixed populations of activated sludge microorganisms can extensively metabolize acrylic acid oligomers of seven units or less. Complete mineralization, however, could be confirmed only for the monomer and dimer material, and carbon mass balance data suggested that the true molecular weight cutoff for complete biodegradation was significantly less than the 500–700 Mw range tested.     

Adaptive sampling and analysis programs for contaminated soils

Adaptive sampling and analysis programs (ASAPs) provide a cost-effective alternative to traditional sampling program designs. ASAPs are based on field analytical methods for rapid sample turnaround and field-based decision support for guiding the progress of the sampling program. One common objective of ASAPs is to delineate contamination present in soils, either to support feasibility studies or remedial action designs. An ASAP based on portable gas chromatograph/ mass spectrograph (GC/MS) technologies developed at Tufts University combined with decision support tools created at Argonne National Laboratory was used to delineate explosives contamination in soils at Joliet Army Ammunition Plant, Joliet, Illinois. Tufts' GC/MS technologies provided contaminant-specific identification and quantification with rapid sample turnaround and high sample throughput. Argonne's decision support tools estimated contamination extent, determined the uncertainty associated with those estimates, and indicated where sampling should continue to minimize uncertainty. In the case of Joliet, per sample analytical costs were reduced by 75 percent as compared to the cost of off-site laboratory analyses for explosives. The use of an ASAP resulted in a much more accurate identification and delineation of contaminated areas than a traditional sampling program would have with the same number of samples collected on a regular grid. While targeting explosives contamination in soils at Joliet, the ASAP technologies used in this demonstration have much broader application.     

Are Recent Watershed Disturbances Associated with Temporal and Spatial Changes in Water Quality of Lake George, New York, USA?

a (Chl a), silica (Si), and chloride (Cl) through the use of proper statistical techniques. Results indicate no statistically significant changes in the concentrations of TP, Chl a, or Si in the spring or summer from 1981 to 1993. A significant temporal trend of increase in Cl concentration is, however, detected. This is perhaps the strongest evidence that the development of the Lake George watershed has affected lakewater chemistry. In spring, the concentrations of TP, Chl a, Si, and Cl, averaged over all 13 years, were higher in the south basin, but differences are not statistically significant (i.e., P > 0.05). In summer, Si was slightly but significantly lower, and Cl was nonsignificantly higher in the south basin. Significant interactions between temporal and spatial changes are detected based only on summer values of TP and Chl a, indicating differential trends of change for these two variables in the south and north basins during the last 13 years.     

Spatial and temporal trends in surface water and sediment contamination in the Laurentian Great Lakes

Data from recent sediment and surface water surveys have been collated and mapped to illustrate the spatial distribution of contaminants across the entire Great Lakes basin. Information from historical surveys, together with data from surface water monitoring programs in three major connecting channels, has also been collated in order to evaluate temporal trends. In general, Lakes Superior and Michigan exhibited the lowest levels of sediment contamination while Lake Ontario had the highest. Contaminants such as gamma-HCH (lindane) and dieldrin were ubiquitous in surface waters across the entire basin, which was indicative of atmospheric sources. The distribution of other compounds including hexachlorobenzene, octachlorostyrene and mirex indicated the presence of local sources within the watersheds of the connecting channels. Surficial sediment contamination was found to have decreased markedly since the late 1960s and 1970s. Similarly, surface water contamination decreased over the period 1986-1997 with concentrations of dieldrin, hexachlorobenzene, octachlorostyrene and mirex reduced by over 50%. However, the spatial distributions of both sediment and surface water contamination indicate that further effort is warranted in reducing local sources of contaminants, particularly in Lake Ontario.