Levels and trends of polybrominated diphenylethers and other brominated flame retardants in wildlife

In this paper, we review the available data for polybrominated diphenylethers (PBDEs) and other flame retardants in wildlife, with the exception of fishes from Europe and North America which are covered in more detail elsewhere. More data are available for PBDEs than for other compounds, and these show that some of these compounds have become widely distributed in the environment, being found in samples from Europe, Australia, Azerbaijan, North America and the Arctic. Most available data relate to birds and their eggs and marine mammals, but the results of two food web studies are also included. The detection of PBDEs in pelagic marine mammals which feed in deep offshore waters, including baleen whales, indicate that these compounds have found their way into deep-water, oceanic food webs as well as the coastal/shallow sea examples described in detail. In the North Sea study, the most marked increase in lipid-normalised concentrations of six BDE congeners occurred during transfer from predatory fish to marine mammals. In the St. Lawrence Estuary study, marked differences in the ratios observed between species suggested that some fish species may be able to metabolise BDE99.A number of time trend studies have also been conducted, notably in guillemot eggs from Sweden (1969-2000), beluga whales from the Canadian Arctic (1982-1997 and 1989-2001) and from the St. Lawrence Estuary (1988-1999), and ringed seals from the Canadian Arctic (1981-2000). In the temperate latitudes, from these and other studies (e.g. in dated sediment cores), PBDE concentrations began to rise earlier than in those from high latitudes, in line with data for production and use. These trends have now slowed in many cases. Declines could be expected in Europe for many congeners following the cessation of manufacture and use of the penta-mix formulation in the EU, though these are not yet apparent in environmental samples. In Arctic biota, however, the rapidly rising concentrations seen currently in Canada could be expected to continue for some time, reflecting continued production and use of the penta-mix formulation in North America (>95% of the world total) and the impact of long-range atmospheric transport.     

Sorption of selenium anionic species on apatites and iron oxides from aqueous solutions

The sorption of selenite and selenate ions from aqueous solutions was investigated on hydroxyapatite, fluorapatite, goethite and hematite, in order to simulate the behavior of radioactive selenium in natural or artificial sorbing media. Correlation studies with acido-basic properties and solubility of the solids were also performed. The sorption is pH dependant, but these solids are very efficient for retaining selenite at pH values generally encountered in natural waters, with however higher K(d) values for oxides than apatites. Selenate ions are much less sorbed than selenite. Several methods such as electron microscopy and spectroscopic techniques were used to identify the sorption mechanisms. In the case of hydroxyapatite, sorption proceeds by substitution of phosphate groups in the lattice of the apatite crystal in the superficial layers of the solid. In the case of goethite and hematite, sorption can be interpreted and modeled by a surface complexation process, but there is a discrepancy between sorption site densities for selenite and for protons.     

UNIT HYDROGRAPHS DERWED FROM THE NASH MODEL1

ABSTRACT: Unit hydrograph ordinates are often estimated by deconvoluting excess rainfall pulses and corresponding direct runoff. The resulting ordinates are given at discrete times spaced evenly at intervals equal to the duration of the rainfall pulse. If the new duration is not a multiple of the parent duration, hydrograph interpolation is required. Linear interpolation, piece-wise nonlinear interpolation and graphical smoothing have been used. These interpolation schemes are expedient but they lack theoretical basis and can lead to undesirable results. Interpolation can be avoided if the instantaneous unit hydrograph (IUH) for the watershed is known. Here two issues connected with the classic Nash IUH are examined: (1) how should the Nash parameters be estimated? and (2) under what conditions is the resulting hydrograph able to reasonably represent watershed response? In the first case, nonlinear constrained optimization provides better estimates of the IUH parameters than does the method of moments. In the second case, the Nash IUH gives good results on watersheds with mild shape unit hydrographs, but performs poorly on watersheds having sharply peaked unit hydrographs. Overall, in comparison to empirical interpolation alternatives, the Nash IUH offers a theoretically sound and practical approach to estimate unit hydrographs for a wide variety of watersheds.     

RECYCLING INPUT DATA DURING ANALYTIC ELEMENT MODELING NEAR INDIANAPOLIS,INDIANA1

ABSTRACT: Overlapping and adjacent ground water investigations are common in areas where aquifers are threatened by industrial development. In the Indianapolis area in Marion County, Indiana, a patchwork of ground water flow models have been used during the past 20 years to evaluate ground water resources and to determine the effects of local contamination. In every case these ground water models were constructed from scratch. Site specific finite difference grids or finite element meshes inhibit the direct reuse of input data when the area of interest shifts. Because the aquifer is not discretized into a grid or mesh with analytic element models, there are unique opportunities for direct reuse of model input data. In two applications of this principle we illustrate how the newly emerging analytic element method allows a fairly straightforward reuse of model input data from previous models in the same general area. In analytic element models of Central Indiana, streams and their tributaries are represented in different resolutions. Input data items of several modeling studies are stored and cataloged on disk in such a manner that they can be selectively retrieved by a data management program PREPRO. In this manner, a new ground water model can be set up quickly with input data which have been previously defined and tested during model calibration.     

Establishment and Growth of Experimental Grass Species Mixtures on Coal Mine Sites Reclaimed with Municipal Biosolids

The Surface Mining Control and Reclamation Act of 1977 requires that coal mine sites in the United States be reclaimed to establish vegetative cover that is diverse, native, and capable of plant succession. However, there is a question as to whether vegetation established on coal mine sites reclaimed with biosolids is diverse and capable of plant succession. The influx of nutrients with the addition of biosolids leads to long-term dominance by early-successional species, most notably grasses, and consequently, a low establishment of woody and volunteer species. Additionally, many grass species commonly planted in reclamation have aggressive growth habits that lead to their dominance in coal mine plant communities. The establishment and growth of selected grass mixes was evaluated to determine whether alternative grass mixes would be less competitive with woody and volunteer species as compared to commonly used grass mixes. Percent vegetative cover, species richness, and the survival of direct-seeded woody species were assessed for each treatment grass mixture. It was found that Poa compressa and a mixture of P. compressa, Panicum virgatum, and Trifolium repens provided adequate coverage while still allowing the highest species richness and survival of woody species. Use of these species mixtures in coal mine reclamation with biosolids in the eastern United States would likely lead to establishment of a more species-rich plant community with a greater woody species component while still providing erosion control and site protection.     

Saltcedar control and water salvage on the Pecos river, Texas, 1999-2003

A large scale ecosystem restoration program was initiated in 1997 on the Pecos River in Western Texas. Saltcedar (Tamarix spp.), a non-native invasive tree, had created a near monoculture along the banks of the river by replacing most native vegetation. Local irrigation districts, private landowners, federal and state agencies, and private industry worked together to formulate and implement a restoration plan, with a goal of reducing the effects of saltcedar and restoring the native ecosystem of the river. An initial management phase utilizing state-of-the-art aerial application of herbicide began in 1999 and continued through 2003. Initial mortality of saltcedar averaged about 85-90%. Monitoring efforts were initiated at the onset of the project to include evaluating the effects of saltcedar control on salinity of the river water, efficiency of water delivery down the river as an irrigation water source, and estimates of water salvage. To date, no effect on salinity can be measured and irrigation delivery was suspended in 2002-2003 due to drought conditions. Water salvage estimates show a significant reduction in system water loss after saltcedar treatment. However, a flow increase in the river is not yet evident. Monitoring efforts will continue in subsequent years.