THE MISUSE OF HYDROLOGIC UNIT MAPS FOR EXTRAPOLATION,REPORTING, AND ECOSYSTEM MANAGEMENT1

ABSTRACT: The use of watersheds to conduct research on land/water relationships has expanded recently to include both extrapolation and reporting of water resource information and ecosystem management. More often than not, hydrologic units (HUs) are used for these purposes, with the implication that hydrologic units are synonymous with watersheds. Whereas true topographic watersheds are areas within which apparent surface water drains to a particular point, generally only 45 percent of all hydrologic units, regardless of their hierarchical level, meet this definition. Because the area contributing to the downstream point in many hydrologic units extends far beyond the unit boundaries, use of the hydrologic unit framework to show regional and national patterns of water quality and other environmental resources can result in incorrect and misleading illustrations. In this paper, the implications of this misuse are demonstrated using four adjacent HUs in central Texas. A more effective way of showing regional patterns in environmental resources is by using data from true watersheds representative of different ecological regions containing particular mosaics of geographical characteristics affecting differences in ecosystems and water quality.     

Effect of soil solids concentration in batch tests on the partition coefficients of organic pollutants in landfill liner-soil materials

 The effect of the soil solids concentration in batch tests on the measured values of the partition coefficient (K _p) of organic pollutants in landfill liner-soil material was investigated. Since this study was based on the results of batch and column tests conducted independently, there were limitations to the conclusions derived. The organic compounds tested were benzene, methylene chloride, toluene, trichloroethylene, and p-xylene. The results of this study showed that as soil solids concentrations increased, the measured K _p values of these organic compounds strongly decreased. The observed values of K _p stabilized when the soil solids concentration was above a certain value. Typical K _p values obtained from batch tests conducted under high soil solids concentrations were close to those obtained from column tests. It was concluded that the K _p values of organic compounds measured under low soil solids concentrations, i.e., less than 100 g/l, may not correctly simulate the field situation. Consequently, the values of K _p obtained with low soil solids concentrations can result in an overestimation of the retardation factor of the landfill liner material. Received: March 14, 2002 / Accepted: August 25, 2002     

Characterisation of Organic Matter and Carbon Cycling in Rehabilitated Lignite-rich Mine Soils

Open-cast lignite mining in the Lusatian mining district resulted in rehabilitated mine soils containing up to four organic matter types: (1) recent plant litter, (2) lignite deposited by mining activity, (3) carbonaceous ash particles deposited during amelioration of the lignite-containing parent substrate and (4) airborne carbonaceous particles deposited during contamination. The influence of lignite-derived carbon types on the organic matter development and their role in the soil carbon cycle was unknown. This paper presents the findings obtained during a six year project concerning the impact of lignite on soil organic matter composition and the biogeochemical functioning of the ecosystem. The organic matter development after rehabilitation was followed in a chronosequence of rehabilitated mine soils afforested in 1966, 1981 and 1987. A differentiation of the organic matter types and an evaluation of their role within the ecosystem was achieved by the use of ¹⁴C activity measurements, ¹³C CPMAS NMR spectroscopy and wet chemical analysis of plant litter compounds. The results showed that the amount and degree of decomposition of the recent organic matter derived from plant material of the 30 year old mine soil was similar to natural uncontaminated forest soil which suggests complete rehabilitation of the ecosystem. The decomposition and humification processes were not influenced by the presence of lignite. On the other hand it was shown that lignite, which was thought to be recalcitrant because of its chemical structure, was part of the carbon cycle in these soils. This demonstrates the need to elucidate further the stabilisation mechanisms of organic matter in soils.     

Drying of granulated wood ash by flue gas from saw dust and natural gas combustion

At the district heating plant of Kalmar, Sweden an on-line unit for production of granulated wood ash for nutrient recycling on forest soils is being applied. Currently, the granules are dried by hot air from an oil-fired burner. The objective of this work was to investigate how drying by flue gas affects the hardening of granules, or impacts their chemical composition and properties. Ninety-six granule samples were treated by flue gas from natural gas combustion in a laboratory pilot scale flue gas generator. CO₂, CO, O₂, C₃H₈ and NO concentrations were varied during the experiment. Additionally, some samples were treated by flue gas from combustion of sawdust at the heating plant in Kalmar. Drying by flue gases did not affect the chemical composition of granules, but minor effects were seen in their mineralogy. The carbonate content was slightly higher in granules treated with flue gas from natural gas combustion compared to the granules dried by hot air only, when measured by wet chemical methods. Results from XRD analysis imply that the calcite content is higher and the portlandite and arcanite content slightly less in granules treated with flue gas from sawdust combustion compared to the granules dried by hot air only. The results from this investigation showed no negative effects on ash granule composition or physical structure by the use of a flue as a drying medium.     

Paradise Threatened: Land Use and Erosion on St. John, US Virgin Islands

2 /yr, respectively. Geomorphic evidence indicates that plantation agriculture during the 18th and 19th centuries did not cause severe erosion. Since about 1950 there has been rapid growth in roads and development due to increasing tourism and second-home development. Our field investigations identified the approximately 50 km of unpaved roads as the primary source of anthropogenic sediment. Field measurements of the road network in two catchments led to the development of a vector-based GIS model to predict road surface erosion and sediment delivery. We estimate that road erosion has caused at least a fourfold increase in island-wide sediment yields and that current sedimentation rates are unprecedented. Paving the dirt roads and implementing standard sediment control practices can greatly reduce current sediment yields and possible adverse effects on the marine ecosystems surrounding St. John.     

Comparing Environmental Conditions Using Indicators of Pollution Hazard

/ Land use/land cover classifications for 1973 and 1991, derived from the interpretation of satellite imagery, are quantified on the basis of biophysical land units in a study area in southeastern Australia. Nutrient export potentials are estimated for each land unit based on their composition of land use/land cover classes. Spatial and temporal comparisons are made of the land units based on the calculated pollution hazard indicators to provide an insight into changes in the state of the environment and the regional significance of land use changes. For example, one ecosystem, unique to the study, showed a large increase in pollution hazard over the study period as a manifestation of an 11-fold rise in cleared area and an expansion of cropping activities. The benefits to environmental management in general are discussed.KEY WORDS: Land cover change; Nutrient export; Environmental condition; Pollution hazard; Agricultural pollution; Nonpoint source pollution; Diffuse pollution; Environmental degradation     

Quantitative Assessment of the Intertidal Environment of Kuwait I: Integrated Environmental Classification

Quantitative analysis of physical, chemical and biological data of the intertidal zone in Kuwait was undertaken to develop an integrated basis for assessing and protecting this sensitive coastal ecosystem. Cluster analyses were performed to determine the resemblance between the sampling stations based on the sediment composition, the benthic macrofauna and the physico-chemical characteristics of the intertidal sediment/water. Five distinct sub-environments were delineated within the intertidal zone of Kuwait. Each sub-environment was described in terms of number of taxa, mean density of organisms, sediment type, tidal level and dominant organisms. The physico-chemical parameters investigated were found to be unimportant in the distribution of the intertidal benthic macrofauna. On the other hand, sediment type was found to be a major factor in the overall composition of the benthic community. The benthic fauna and related characteristics of the sub-environments could be used as indicators to monitor changes in the intertidal ecosystem and as guides to protection and management of the different coasts. The approach described in this paper could also be adopted elsewhere to provide a sound basis for evaluating environmental impacts and for developing sustainable coastal management.     

Strategic environmental product planning within Philips sound & vision

Until now no structured methodology existed for attuning environmental considerations to the business strategy of companies. The Environmental Competence Centre of Philips Sound & Vision in The Netherlands has developed and tested a methodology for this purpose. This methodology, called Selection of STRrategic Environmen Tal CHallenges (STRETCH), has proven to lead to promising results and should therefore be actively promoted. In this article, the authors show how the application of STRETCH provides the possibility of meeting three main objectives: First, focusing on the incorporation of environmental aspects into the company's business strategy can elicit innovations that may enhance the competitive position of the company by cost reduction and/or higher market shares. Second, the environmental opportunities and threats to be expected in the future can be anticipated in an earlier phase. Through this proactive approach a company can avoid external criticism and take the lead in environmental priority setting. Third, by applying the STRETCH methodology even higher eco-efficiencies are expected to be reached than through incremental, step-by-step environmental improvements.