Relative Importance Of Diffuse Sources Research Articles

Changes in Cd and Zn distribution in sediments after closure of an electroplating industry, Sepetiba bay, Brazil

The spatiotemporal attenuation of Cd and Zn concentrations was assessed in sediments from Sepetiba Bay, which is a coastal system that has been historically impacted by industrial wastes. The evolution of contamination over the years shortly before and after cessation of electroplating industry activities, by the end of 1990's, was elucidated by reviewing the existing datasets for the whole bay area. Metal concentrations exceed Brazilian Sediment Quality Guidelines in most regions, corresponding to concentrations 3 to 4 orders of magnitude higher than background levels and Enrichment Factors reaching values significantly higher than 40 for both elements. In the second decade after electroplating industry closure, the levels of Cd and Zn lowered in most regions of the bay. However, an increase in the relative importance of diffuse sources can mislead the current and future identification of Cd and Zn input, bringing new challenges for environmental monitoring and management for Sepetiba bay.

DIFFUSE POLLUTION ‐ WHAT IS THE NATURE OF THE PROBLEM?

ABSTRACTThis paper considers recent developments in the understanding of diffuse pollution, its generation, transport and impacts. The relative importance of diffuse sources to total pollutant loading must be identified in order to develop appropriate strategies for management.Research has indicated that individual diffuse pollutants respond differently to changing flow conditions and that there is a widespread misconception that higher flows are associated with lower pollutant concentrations. Evidence is presented to highlight this discrepancy and a rationale for load assessment is presented. The implications of this for monitoring within the context of the EU Water Framework Directive are discussed as are the implications for the mitigation of diffuse pollution.

Water quality in Scotland: the view of the regulator

Water quality in Scotland has progressively improved over the past 50 years as the environmental damage, which resulted from the industrial revolution, has been addressed. This paper provides an overview of current water quality in rivers, lochs, estuaries and coastal waters and describes the limited information available on groundwater. The main factors affecting water quality are reviewed, with sewage, diffuse agricultural pollution, acidification and urban drainage identified as the most important. Trends in pollution pressure and levels of investment in pollution control have been used to predict the condition of Scotland's surface water over the next 10 years. Major improvements are expected. However, progress will be slowed by the increased relative importance of diffuse sources of pollution, which are less amenable to legislative controls. Future changes in environmental monitoring are also expected to move the emphasis away from point source pollution. The current freshwater classification schemes are based upon a relatively narrow measure of water quality and are expected to expand to include a wider range of ecological parameters. This will result in an increase in the waters defined as impacted as the effects of other environmental pressures are taken into account. Finally the implications of these changes for the future management of the aquatic environment are assessed.

Diffuse Pollution in the Lagoon of Venice

The hypertrophic conditions of several confined areas in the Lagoon of Venice are but one of the consequences of nutrient discharges from its drainage basin. The monthly distribution of these loads, as well as their spacial subdivision among different tributaries of this characteristic water body, directly affect the growth cycle of macroalgae in it. The magnitude of these loads cannot be precisely measured by direct methods, however, it can be estimated by simulation with appropriate models. A comprehensive study aimed at the determination of these loads is under way as part of a larger intervention program to restore the physical and ecological equilibrium of the Lagoon. This paper focuses on the results of the simulation of diffuse loads generated in the Lagoon watershed. These results were obtained by interfacing a geographical information system (GIS) of the watershed and two models simulating respectively urban and agricultural diffuse pollution. Diffuse loads are then compared with the corresponding point sources to evaluate their relative contributing role in the dystrophic behavior of the Lagoon. The relative importance of diffuse sources is discussed with particular reference to time and space variability of the loads.