Environmental Monitoring Tasks Research Articles

THE STUDY OF DESICCATED PORTIONS OF THE FORMER ARAL SEA BED USING MULTISPECTRAL RADAR IMAGERY

Two Russian specialists in the application of radar imagery to a wide range of environmental monitoring tasks describe the results of aerial and space radar surveys of the dried bed of the Aral Sea. The surveys were carried out at a variety of frequencies, which permit the identification of many diverse features associated with the regression of the sea. Translated by Edward Torrey, Alexandria, VA from: Geografiya i prirodnyye resursy, 1999, No. 4, pp. 83-85.

Rapid coastal survey of anthropogenic radionuclides, metals, and organic compounds in surficial marine sediments

A towed survey system, the GIMS/CS 3, has been developed to enable the rapid measurement and mapping of a variety of physical and geochemical parameters in the surficial sediments of aquatic environments while the survey vessel is underway. With its capability for measuring radiometric, elemental and organic compound constituents of sediments, as well as bathymetry and water quality parameters, the GIMS/CS 3 provides a cost-effective means of performing reconnaissance determinations of contaminant distributions and environmental monitoring tasks over broad geographic regions.

Biological complexity confounds the separation of point- and non-point sources of human impact on the natural world

Identifying process from pattern is one of the most vexing tasks inenvironmental monitoring. Given information on the distribution of speciesin a pre-defined area, together with comprehensive data on how environmentalconditions in that area have altered through time, is it possible toidentify the factors controlling the species‘ layout? Here, the practicalsignificance of this quandary is demonstrated using a series ofenvironmentally-degraded coastal lagoons in New South Wales. The TuggerahLakes (33°17′S,151°30′E) have over the last 50 yearsexperienced significant changes in species‘ distributions. Seagrasses,macroalgae, phytoplankton, molluscs, prawns and the jellyfish Catostylus mosaicus have altered in spatial pattern. Two human activitieshave been blamed for these perturbations: (1) agricultural clearance ofnative vegetation from the catchment, with associated input of top-soil andnutrients; (2) the commissioning of a coal-fired power station in 1967, withmassive uptake and recirculation of lake water for cooling purposes. In thispaper, spatial changes in macrophyte distributions over the last 50 yearsare reviewed in an attempt to identify the true source(s) of perturbation.The model adopted assumes that the power station is a point source of impactwhile nutrient inputs from the catchment are a diffuse source of impact;changes in species distributions can hypothetically be related back to thesesources according to whether they are localised or widespread. However,after a comprehensive analysis of available macrophyte data derived frominterviews, aerial photography and line transect methodologyies theconclusion is reached that changes in biogeographical pattern around theTuggerah Lakes cannot be attributed to specific anthropogenic pressures atanything beyond the coarsest of levels. This is considered to be the normfor most coastal management situations where natural background variation(’noise‘) and the complexity of linkages between physical, chemical andbiological components confounds the identification of causal relationships.The practical implications of this conclusion are discussed in the contextof litigation and remedial management design. Emphasis is placed on theneed to adopt an adaptive approach to estuarine management, incorporatingexplicit recognition of the limitations of available data, and to developnew techniques for identifying cause-effect relationships.

Comparison of detectors with respect to the lower limit of determining the activity of gamma-emitting nuclides

Since the number of tasks in environmental monitoring is increasing, an experimental comparison of the capabilities of various detectors with respect to the lower limit of activity determinations on gamma-emitting nuclides is of interest. Measurements were made with a gamma spectrometer provided with an 800-channel analyzer and detectors of various types and dimensions. The liquid samples were prepared from a radioactive Cs-137 standard solution of class 1 with specific mass activity indicated in the specification data with an error of 3% on the 0.95 confidence level. The DGDK-32A germanium detector with a passive 10-cm-thick lead shield was used to establish experimentally the lower limit of determining the bulk activities of nuclides in a liquid 50-ml sample which was placed directly on the upper lid of the detector; the nuclides Na-24, Mn-54, Co-60, Zn-65, Zr-95, Nb-95, Ru-103, Rh-106, I-131, Cs-137, and Ce-144, which are very important with respect to environmental protection, were considered.