The use of computer models in planning upland land use

The British Ecological Society has suggested that computer‐based techniques could be used in the coordination of policies across different land uses in upland planning. This paper looks briefly at one such technique — a linear programming model — and describes its use at a regional scale for the Sedburgh area in north‐west England. The paper concludes with consideration of why such models are not in more common use.     

Causes of ambient toxicity in the Calleguas Creek watershed of southern California

A combination of toxicity tests, chemical analyses, andToxicity Identification Evaluations (TIEs) were used toinvestigate receiving water toxicity in the Calleguas Creekwatershed of southern California. Studies were conductedfrom 1995 through 1999 at various sites to investigatecauses of temporal variability of toxicity throughout thissystem. Causes of receiving water toxicity varied by siteand species tested. Investigations in the lower watershed(Revolon Slough, Santa Clara Drain, Beardsley Wash)indicated that toxicity of samples to the cladoceran Ceriodaphnia dubia due to elevated concentrations ofthe organophosphate pesticide chlorpyrifos, while causes ofintermittent toxicity to fathead minnows (Pimephalespromelas) and the alga Selanastrum capricornutum wereless clear. Investigations at sites in the middle and upperreaches of the watershed (Arroyo Simi and Conejo Creek)indicated that the pesticide diazinon was the probable causeof receiving water toxicity to Ceriodaphnia. Elevatedammonia was the cause of toxicity to fathead minnows in theupper watershed sites. Results of these and previousstudies suggest that biota are impacted by degraded streamquality from a variety of point and non-point pollutionsources in the Calleguas Creek watershed. Water qualityresource manager's efforts to identify contaminant inputsand implement source control will be improved with thefindings of this study.     

A terrain-based paired-site sampling design to assess biodiversity losses from eastern hemlock decline

Biodiversity surveys are often hampered by the inability tocontrol extraneous sources of variability introduced intocomparisons of populations across a heterogenous landscape. If not specifically accounted for a priori, this noisecan weaken comparisons between sites, and can make itdifficult to draw inferences about specific ecologicalprocesses. We developed a terrain-based, paired-sitesampling design to analyze differences in aquaticbiodiversity between streams draining eastern hemlock (Tsuga canadensis) forests, and those draining mixedhardwood forests in Delaware Water Gap National RecreationArea (USA). The goal of this design was to minimize variancedue to terrain influences on stream communities, whilerepresenting the range of hemlock dominated streamenvironments present in the park. We used geographicinformation systems (GIS) and cluster analysis to define andpartition hemlock dominated streams into terrain types basedon topographic variables and stream order. We computedsimilarity of forest stands within terrain types and usedthis information to pair hemlock-dominated streams withhardwood counterparts prior to sampling. We evaluated theeffectiveness of the design through power analysis and foundthat power to detect differences in aquatic invertebratetaxa richness was highest when sites were paired and terraintype was included as a factor in the analysis. Precision ofthe estimated difference in mean richness was nearly doubledusing the terrain-based, paired site design in comparison toother evaluated designs. Use of this method allowed us tosample stream communities representative of park-wide forestconditions while effectively controlling for landscapevariability.     

Phthalate and alkyl phenol concentrations in soil following applications of inorganic fertiliser or sewage sludge to pasture and potential rates of ingestion by grazing ruminants

Soil concentrations of dioctyl phthalate (DOP) and the alkyl phenols, octyl phenol (OP) and nonyl phenol (NP), after repeated surface applications of sewage sludge to pastures, were investigated. Liquid sludge was applied at a rate of 2.25 tonnes dry matter (DM) per hectare to each of three treated (T) plots on three occasions during the summer and two occasions in the early spring over a period of 2.5 years. Control (C) plots were treated with inorganic fertiliser containing amounts of nitrogen equivalent to those applied to the treated plots. At between 69 and 81 days after the application of sludge, 15 separate soil samples were collected from one half of each of the plots (Experiment 1). Concentrations (microg g(-1)) of DOP were higher (P < 0.001) than those of NP, while those of OP were generally below detectable levels. Mean soil concentrations of DOP were not significantly different in T and C plots [0.233 vs. 0.155 microg g(-1); standard error of the difference (SED) = 0.046; not significant (NS)], partly because there was already a relatively large amount of DOP present. NP concentrations were, however, significantly higher in T than in C plots (0.021 vs. 0.013 microg g(-1) SED = 0.002; P < 0.05). There was no consistent change over time in the mean soil concentrations of these compounds when sampled at intervals of 3-6 months. Concentrations in soil samples collected at monthly intervals following sludge application indicated that the variation in concentrations of these endocrine-disrupting compounds (EDC) was unrelated to time since sludge application. Rates of soil ingestion, expressed as the percentage of DM intake represented by soil, were higher during the winter than the summer (5.40 vs. 1.17; SED = 0.360; P < 0.001) and estimated daily intakes of DOP and NP were up to 150 microg and 8 microg, respectively. It is concluded that the application of sewage sludge to pasture does not increase soil concentrations of phthalate (as DOP) or alkyl phenols. Thus, the risk of increased exposure to these EDC as a result of sludge application is small. However, the small effect of sludge application on soil concentrations may be largely a reflection of the relatively high concentrations of DOP already present in the soil, which may be biologically significant.     

Metal deposition patterns in central Scotland,as determined by Lichen transplants

Lichen transplants of Hypogymnia physodes were used in a high-density network of sites for collecting airborne metals from the atmosphere in Armadale, a small industrial town in central Scotland. The mapping of the concentrations of various metals revealed a gradient of metal values which decreased outwards from the town's steel foundry. The findings were discussed in the context of a previous epidemiological investigation of lung disease in the town.     

Optimizing the removal of carbon phases in soils and sediments for sequential chemical extractions by coulometry

We have developed a coulometric technique to optimize the removal of the carbonate and organic fractions for sequential chemical extractions of soils and sediments. The coulometric system facilitates optimizing these two fractions by direct real-time measurement of carbon dioxide (CO2) evolved during the removal of these two fractions. Further analyses by ICP-MS and alpha-spectrometry aided in interpreting the results of coulometry experiments. The effects of time, temperature, ionic strength and pH were investigated. The sensitivity of the coulometric reaction vessel/detection system was sufficient even at very low total carbon content (< 0.1 mol kg-1). The efficiency of the system is estimated to be 96% with a standard deviation of 8%. Experiments were carried out using NIST Standard Reference Materials 4357 Ocean Sediment (OS), 2704 Buffalo River Sediment (BRS), and pure calcium carbonate. Carbonate minerals were dissolved selectively using an ammonium acetate-acetic acid buffer. Organic matter was then oxidized to CO2 using hydrogen peroxide (H2O2) in nitric acid. The carbonate fraction was completely dissolved within 120 min under all conditions examined (literature suggests up to 8 h). For the OS standard, the oxidation of organic matter self-perpetuates between 45 and 50 degrees C, a factor of two less than commonly suggested, while organic carbon in the BRS standard required 80 degrees C for the reaction to proceed to completion. For complete oxidation of organic matter, we find that at least three additions of H2O2 are required (popular methods suggest one or two).     

A national ozone biomonitoring program--results from field surveys of ozone sensitive plants in northeastern forests (1994-2000)

Ozone biomonitoring is a detection and monitoring techniquethat involves documenting ozone-induced visible injury toknown ozone-sensitive species under conditions of ambientexposure. The USDA Forest Service administers a long-term,nationwide ozone biomonitoring program to address public andscientific concerns about ozone impacts on forest health. Asystematic grid is used as the basis for biomonitoring sitelocations. At each site, trained field crews evaluate amaximum of thirty plants of up to six species and record the amount and severity of leaf-injury on individualplants. Injury from ozone was found more often on biomonitoring sites in the eastern Unites States than in theinterior or west-coast areas. Further results from thenortheast reveal that in any year, there is a higherpercentage of ozone-injured plants with more severe symptomsin areas with relatively high ozone concentrations than inareas with relatively low ozone. In very dry years (e.g.,1999) the percentage of injured plants and injury severityestimates are both sharply reduced even though ambient ozoneexposures are high. These findings demonstrate thatbiomonitoring data provide meaningful evidence of when highozone concentrations during the growing season have biologicalsignificance. Any assessment of ozone stress in the forestenvironment must include both biomonitoring (i.e., plantresponse) and air quality data to be complete.     

Book reviews

Common Property Economics: A General Theory and Land Use Applications

Glenn G. Stevenson

Cambridge, Cambridge University Press, 1992, XIV + 256pp., £35

Controversial Issues in Environmental Policy: Science vs Economics vs Politics

Kent E. Portney

London, Sage, 1992, 181 pp. £22.00 hb., £10.95 pb.

Economics of Natural Resources and the Environment

E. Kula

London, Chapman & Hall, 1992, 287 pp., £40

Policy Implications of Greenhouse Warming: Mitigation, Adaptation and the Science Base

Committee on Science, Engineering and Public Policy (US), Panel on Policy

Implications of Greenhouse Warming

Washington, DC, National Academy Press, 1992, xxiii + 918 pp., $89.95 hb.

Contemporary Rural Systems in Transition, Volume 1: Agriculture and Environment, Volume 2: Economy and Society

I. Bowler, C. Bryant & M.Nellis (Eds)

Wallingford, CAB International, 1992, 288 pp. + 336 pp., £35 + £40 (2 vols. £70) hb.

Third World Cities: Problems, Policies and Prospects

John Kasarda & Allan Parnell (Eds) London, Sage, 1993, 310 pp., £19.50 pb.

Pricing the European Environment

Stale Navrud (Ed)

Oxford, Oxford University Press/Scandinavian University Press, 1992, 288 pp., £30.00 hb.     

Regulation of nitrate and ammonium uptake in the Greenland Sea

The uptake of nitrate and ammonium was investigated experimentally during early spring 1989 in the Greenland Sea, with particular attention placed on the roles of irradiance, nitrogen concentrations and nitrateammonium interactions. The phytoplankton assemblage was dominated by the colonial prymnesiophyte Phaeocystis pouchetii. Nitrate concentrations ranged from undetectable at the end of the cruise to greater than 10 M, and ammonium levels ranged from less than 0.1 to 1.9M. The uptake of both nitrate and ammonium as a function of irradiance was found to be a saturation response. Photoinhibition occurred and was found to be greater for ammonium uptake. Ammonium uptake also saturated at irradiance levels five times lower than those needed to saturate nitrate uptake. Nitrate and ammonium uptake as a function of nitrogen concentration also was characterized by a saturation response, with the estimated half-saturation constant (K _s) value for nitrate uptake being 0.29 M. Elevated ammonium concentrations inhibited nitrate uptake, and the response appeared to be one of exponential decrease with increasing concentrations of ammonium. The most important factor in the Greenland Sea influencing ammonium uptake during the spring was irradiace, while both irradiance and ammonium concentrations played major roles in regulating nitrate uptake and new production.