Operation and maintenance of water projects and services in Latin America

This paper concentrates on two aspects of the vast subject of '… water projects and services'. Even though the questions tackled may affect different water uses, this analysis is focused on operation and maintenance of water supply systems and the institutions that service them. The paper seeks to analyse some of the obstacles which impede the attainment of better performance in the operation and maintenance of water projects. It tackles the institutional problems and restrictions which must be overcome to speed up the adoption of operational patterns which will lead to a better use of available capacities.     

Estimation of Cumulative Frequency Distribution for Carbon Monoxide Concentration from Wind-Speed Data, in Buenos Aires (Argentina)

In this article we apply and test a methodology to estimate cumulative frequency distribution for air pollutant concentration from wind-speed data. We use the inverse relationship after Simpson et al. (Atmospheric Environment, 19, 75–82, 1985) between the opposing percentile values in the statistical distributions for air pollutant concentrations and wind-speed data. This relationship is valid, irrespective of the statistical distributions of both variables, if an inverse relationship between them is also applicable. The available data are five years of 8-h average carbon monoxide concentration and 8-h mean wind-speed, observed in Buenos Aires (Argentina). The performance of the obtained empirical expressions in estimating cumulative frequency distributions for 8-h CO is statistically evaluated. The results show that it is possible to obtain an acceptable cumulative frequency distribution for 8-h CO concentration at the site if the cumulative frequency distribution for wind-speed is known. Q–Q plots show a good agreement between estimated and observed values. From our data, the mean relative error of the estimations was found to be as much as 8.0%.     

An Ecological Integrity Index for Littoral Wetlands in Agricultural Catchments of Semiarid Mediterranean Regions

The main goal of the present study was to develop an ecological integrity index for littoral wetland management and conservation in semiarid Mediterranean areas that have been highly impacted by agriculture, including the selection of pressure and state indicators at landscape and wetlands scales that reflect the status, condition, and trends of wetlands ecosystems. We used a causality framework based on the relationship between pressure of anthropogenic activities and the ecological state of wetlands and their catchments, integrating environmental, biologic, economic, and social issues. From the application of 51 indicators in 7 littoral wetlands in the southeastern Iberian Peninsula, we selected 12 indicators (5 at catchment scale and 7 at wetland scale) to constitute the ecological integrity index proposed. The potential nitrogen export per area at catchment scale and the potential relative nitrogen export from the area surrounding the wetlands were the best pressure single predictors of state indicators with a causal relationship with environmental meaning. Wetlands in catchments with more agriculture had less ecological integrity than those in less impacted areas. A wide riparian zone in some wetlands acts as a buffer area, diminishing the effects of intensive agriculture. The index of ecological integrity developed here has a number of essential characteristics that make it a useful tool for ecosystem managers and decision-makers. The index can be used to (1) assess and control ecological integrity, (2) diagnose probable causes of ecological impairment, (3) establish criteria for protecting and restoring wetland ecosystems, and (4) integrate catchment management. Published online     

Landform Classification for Land Use Planning in Developed Areas: An Example in Segovia Province (Central Spain)

Landform-based physiographic maps, also called land systems inventories, have been widely and successfully used in undeveloped/rural areas in several locations, such as Australia, the western United States, Canada, and the British ex-colonies. This paper presents a case study of their application in a developed semi-urban/suburban area (Segovia, Spain) for land use planning purposes. The paper focuses in the information transfer process, showing how land use decision-makers, such as governments, planners, town managers, etc., can use the information developed from these maps to assist them. The paper also addresses several issues important to the development and use of this information, such as the goals of modern physiography, the types of landform-based mapping products, the problem of data management in developed areas, and the distinctions among data, interpretations, and decisions.     

Human exposure to dioxins through the diet in Catalonia,Spain: carcinogenic and non-carcinogenic risk

The main objectives of this study were to estimate the dietary intake of dioxins by the population of Catalonia, Spain, to determine which food groups showed the greatest contribution to this intake, and to assess the health risks potentially associated with the dietary dioxin intake. From June to August 2000, food samples were randomly acquired in seven cities of Catalonia. Dioxin concentrations were determined in 108 samples belonging to the following groups: vegetables, fruits, pulses, cereals, fish and shellfish, meats and meat products, eggs, milk and dairy products, and oils and fats. Estimates of average daily food consumption were obtained from recent studies. Total dietary intake of dioxins for the general population of Catalonia was estimated to be 95.4 pg WHO-TEQ/day (78.4 pg I-TEQ/day), with fish and shellfish (31%), diary products (25%), cereals (14%) and meat (13%) showing the greatest percentages of contribution to dioxin intake. The contribution of all the rest of food groups to the total dietary intake was under 20%. The non-carcinogenic risk index of dioxin intake through the diet was in the range 0.34-1.36, while the carcinogenic risk level was 1,360 excess cancer over a lifetime of 70 years. Our results corroborate the decreasing tendency in dietary intake of dioxins found in recent studies (2000-2001) from various countries.     

Plant uptake of cadmium-109 and zinc-65 at different temperature and organic matter levels

The uptake of 109Cd and 65Zn and their stable isotopes by ryegrass (Lolium multiflorum Lam.), grown on two different soil types, was investigated in climatically controlled growth chambers at 9 and 21 degrees C. The soils were treated with 0 and 4% organic matter (pig [Sus scrofa] manure) and spiked with 109Cd and 65Zn before sowing. The organic matter addition resulted in increased uptake of the 109Cd, Cd, and Zn by ryegrass, but the uptake of 65Zn was decreased. The latter effect was ascribed to isotopic dilution of 65Zn as the amount of stable Zn in the plant tissues increased with the organic matter addition. The effect of temperature was more pronounced than that of organic matter addition, and the uptake of both 109Cd and 65Zn and their stable isotopes was higher in ryegrass grown at 21 degrees C than that grown at 9 degrees C. Results from fractionation and speciation analysis of soil cadmium and zinc were correlated with plant uptake, and there was a good consistency between observed plant uptake and the physico-chemical forms of cadmium and zinc in soil and soil solution presumed to be plant available.     

Using Decision Analysis to Choose Phosphorus Targets for Lake Erie

Lake Erie water quality has improved dramatically since the degraded conditions of the 1960s. Additional gains could be made, but at the expense of further investment and reductions in fishery productivity. In facing such cross-jurisdictional issues, natural resource managers in Canada and the United States must grapple with conflicting objectives and important uncertainties, while considering the priorities of the public that live in the basin. The techniques and tools of decision analysis have been used successfully to deal with such decision problems in a range of environmental settings, but infrequently in the Great Lakes. The objective of this paper is to illustrate how such techniques might be brought to bear on an important, real decision currently facing Lake Erie resource managers and stakeholders: the choice of new phosphorus loading targets for the lake. The heart of our approach is a systematic elicitation of stakeholder preferences and an investigation of the degree to which different phosphorus-loading policies might satisfy ecosystem objectives. Results show that there are potential benefits to changing the historical policy of reducing phosphorus loads in Lake Erie.     

Land Evaluation in a Salt-Affected Irrigated District Using an Index of Productive Potential

2 semiarid irrigated area with salt-affected soils. The available soil map is at 1:100,000 scale and its mapping units are used for the land evaluation with the FAO framework. These data are then elaborated using the index value method. This procedure gives a map of land evaluation units and a table that rates the productive potential of these units for six crops: alfalfa, barley, maize, rice, sunflower, and wheat.     

Effect of culture conditions on the formation of struvite by Myxococcus xanthus

The amount of struvite (MgNH₄PO₄·6H₂O) produced by Myxococcus xanthus as well as the culture parameter values (pH, total phosphorus, total Kjeldahl nitrogen) were dependent on the culture medium used. Struvite formation started during the exponential phase and the maximum concentration was observed at the beginning of stationary growth phase. The addition of each medium component to the liquid culture influenced the amount of crystal produced. This amount did not depend on the pH increase during the culture period. The moment of the bacterial growth phase, at which each medium component was added, influenced the struvite formation.