Remediation of an oily leachate pond in Estonia.

Until recent years, waste oil and oil-contaminated waters commonly ended up in landfills. At some dump sites, ponds of oily liquids and leachate were formed. To remediate such ponds, an interdisciplinary approach is now required, keeping costs at an affordable level, particularly in countries with changing economies. From 1974 to 1993, liquid oily wastes taken to the Laguja landfill, in Estonia, were disposed of in a pond with a surface area of 9800 m2. It was estimated that the pond contained 4500-6000 m3 of oily water and 3500 m3 of oil-containing bottom sediments. This study aimed at developing an environmentally sound and cost-effective method for remediation of the oily liquids, leachate and contaminated underlying sediment material, to meet the existing legal demands. It was concluded that treatment of contaminated water is well established and the procedures carried out to meet the regulatory demands achieved satisfactory results. However, regarding treatment of sediments it was concluded that legal and technological aspects, as well as monitoring procedures are not fully established and are usually underestimated. Laboratory investigations can provide valuable information in decision-making, and contribute to effective full-scale remediation planning.     

STREAM HEALTH RANKINGS PREDICTED BY SATELLITE DERIVED LAND COVER METRICS1

ABSTRACT: Land cover and land use change have long been known to influence the chemical, physical, and biological characteristics of streams. This study makes use of land cover maps derived from fine resolution satellite imagery and an extensive stream quality dataset to determine the relationship between small watershed health rankings and land cover composition and configuration. Landscape metrics were derived from digital impervious surface area (ISA), tree cover (percent), and agricultural crop maps within Montgomery County, Maryland. Watershed rankings were developed by state and county collaborators (MD‐DNR and MCDEP) using extensive biological and chemical measurements. In stepwise logistic regression models the factors accounting for the most variation in stream health ranking were the percent ISA, followed by the percent of tree cover. Riparian buffer zone tree cover was also a significant predictor. Of the metrics that considered the spatial configuration of the landscape, a contagion index and the percent of ISA in the flow path from the ISA to the stream were also found to be significant predictors of stream health. Despite limited ability to characterize landscape configuration or narrow riparian buffer zone vegetation with coarser resolution imagery (from Landsat), model results were not significantly different from those based on the use of fine‐resolution ISA information, suggesting that broader area applications of the approach are possible. The results indicate that management practices designed to improve stream water quality should focus on the amount of ISA and tree cover in both the watershed and within the buffer zone.     

Trial burn activities for a mixed waste incinerator

The Consolidated Incineration Facility (CIF) is located on the Savannah River Site (SRS), owned by the US Department of Energy and managed by BNFL, Inc. for the Westinghouse Savannah River Company. SRS received permits from the South Carolina Department of Health and Environmental Control (SCDHEC) and the US Environmental Protection Agency (EPA), Region IV to construct and operate the CIF, a hazardous, radioactive and mixed waste incinerator. This paper presents the results of the trial burn conducted on the CIF in April 1997 which is the initial demonstration of compliance with the permits. The incinerator is currently operating under approved post-trial burn conditions while the trial burn results are being evaluated. A final operating permit is anticipated in the fall of 1998.     

Emissions from baled municipal solid waste: II. Effects of different treatments and baling techniques on the emission of volatile organic compounds.

This paper focuses on the volatile organic compound emissions from baled municipal solid waste (MSW). The analytical methodology was based on sampling with adsorbent tubes once a month during seven occasions within a time period of 1 year. Automated analyses were carried out on-line work-up with thermal desorption directly connected to a gas chromatograph-mass spectrometer. The effect of different baling techniques, cylindrical and rectangular baling was compared. It was found that cylindrically baled MSW emitted larger concentration of esters than their rectangular counter parts. Conversely, aromatic compounds emissions dominated in rectangularly baled MSW. This indicates that different degradation mechanisms operate in the waste bales. Cylindrical and rectangular bales are generally wrapped with six layers of 250 microm thick low density polyethylene (LDPE). It was observed that by wrapping an extra six layers of LDPE film onto the bales, the emissions from cylindrical bales increased while emissions from the rectangular counterpart decreased. Over time, the volatile organic compound emissions from cylindrical bales decreased two orders of magnitudes from 96.2 +/- 20.8 microg m(-3) in September 2003 to 0.80 +/- 0.07 microg m(-3) in July 2004. The rectangular bales exhibited an almost identical relative emission reduction from 54.4 +/- 4.3 microg m(-3) in September 2003 to 0.46 +/- 0.02 microg m(-3) in July 2004. Future work will concentrate on full-scale storages, taking into account waste type, storage size, temperature development and the different baling techniques among other variables.     

Chemical communication and coevolution in an ant–plant mutualism

Protective ant–plant interactions provide valuable model systems to study mutualisms. Here, we summarise our recent research on chemical and physiological adaptations that contribute to the stabilisation of the mutualism between Mesoamerican Acacia host plants and their Pseudomyrmex ant inhabitants against exploiters, that is, species using host-derived rewards without rendering a service. Acacia hosts produce food bodies (FBs) and extrafloral nectar (EFN). Both types of reward are chemically adapted to their specific function as ant food and protected from different exploiters. FBs contained higher amounts of specific proteins than the leaves from which they originate. EFN possessed amino acids making it attractive for the mutualist ants and an invertase making its carbohydrate composition nutritionally suitable for the mutualists but unattractive for generalists. Moreover, pathogenesis-related proteins such as glucanases, chitinases and peroxidases were found in EFN, which likely serve as protection from microorganisms. Digestive adaptations were found that make workers of the ant mutualists dependent on the host-derived food sources, a mechanism that likely counteracts the evolution of cheaters. The ants also possessed a high diversity of bacterial associates, several of which appeared involved in nitrogen fixation, thus contributing to the nutrition of these ‘vegetarian’ ants. By contrast, a non-defending ant species that parasitises the host plants appeared physiologically less adapted to the host-derived food rewards; this species, thus, likely is competitively inferior when colony growth is limited by plant-derived rewards. In summary, several physiological adaptations of both host plants and ants stabilise the Acacia–Pseudomyrmex mutualism against exploitation.     

Tolerance and metabolism of phenol and chloroderivatives by hairy root cultures of Daucus carota L

Hairy root cultures are shown to be suitable experimental systems to screen higher plants for tolerance to various inorganic and organic pollutants, and for determining the role of the root matrix in the uptake and further metabolism of contaminants. A number of clones were obtained by infection of carrot tissues with Agrobacterium rhizogenes and two (the fastest and the slowest growing root clones) were chosen for further experimentation. Both clones showed a similar degree of tolerance towards phenol and its chlorinated derivatives, i.e. the growth of root biomass was maintained in concentrations of phenol equivalent to 1000 micromol/l, whilst the chlorophenols were tolerated only at concentrations 20 times lower (50 micromol/l). Transformed carrot roots were able to remove more than 90% of the exogenous phenolic compounds from the culture medium within 120 h after treatment. Metabolism of these compounds occurred in the root tissue and was accompanied by an increase in peroxidase activity.     

Feasibility and costs of phosphorus application limits on 39 U.S. swine operations

Concerns about manure P and water quality have prompted new regulations imposing P limits on land application of manure. Previous research established that P limits increase land needs for animal feeding operations. We evaluated the effect of N, annual P, and rotation P limits on the feasibility of manure management. A mechanistic model characterized manure management practices on 39 swine operations (20 unagitated lagoon and 19 slurry operations) in five states (Iowa, Missouri, North Carolina, Oklahoma, and Pennsylvania). Extensive information collected from each operation was used to determine effects of manure storage type, ownership structure, and application limits on attributes of manure management. Phosphorus limits had substantially greater effect on slurry operations, increasing land needs 250% (0.3 hectares per animal unit [AU]) and time for manure application 24% (2.5 min AU(-1)) for rotation P limits and 41% (4.4 min AU(-1)) for annual P limits. Annual P limits were infeasible for current land application equipment on two operations and had the greatest effect on time and costs because they required all but three slurry operations to reduce discharge rate. We recommend implementing rotation P limits (not to exceed crop N need) to minimize time effects, allow most farmers to use their current manure application methods, and allow manure to fulfill crop N and P needs in the year of application. Phosphorus limits increased potential manure value but would require slurry operations to recover at least 61% of manure value through manure sales. Phosphorus limits are likely to shape the U.S. swine industry through differential effects on the various sectors of the swine industry.