Analysis and Control of Nonpoint Nitrate Pollution of Municipal Water Supply Sources

The Resources and Environment Area (REN) of IIASA is dealing with, among other problems, pollution of water resources caused by agricultural activities. For example, nitrate pollution of water resources is very dangerous in many water supply regions. In April 1980, an exploratory study on nonpoint nitrate pollution of municipal water supply sources was initiated as a collaborative study between REN and several institutions from the IIASA National Member Organization countries. The first objective of the study is to explore approaches to analysis and control of the problem in question. The second objective is to generate a methodological outline focusing on the integration of the most relevant results of the exploratory phase. Based on this, the overall direction of further REN research can be established more clearly, which is the third objective. This paper summarizes the work concerning the first two objectives done at IIASA between April and October 1980. The paper is based mostly on source material kindly furnished by the cooperating organizations from the NMO countries. It has been structured largely according to the main topics of a related Task Force Meeting which will be held at IIASA in February 1981. In doing so, the paper is intended to serve as a basis for the discussion at this meeting on the attainment of the study objectives mentioned above

The Management Alternatives for Control of Nonpoint Nitrate Pollution of Municipal Water Supply Sources

Regional water management aims at satisfying different supply interests, where these interests are often conflicting. In particular, the competing interests of agriculture, the environment, and municipal water supply, are becoming increasingly important. In this setting of regional water management, nonpoint nitrate pollution of municipal water supply sources is one of the most severe problems. At present, this problem is particularly acute in developed regions with high levels of fertilizer application, but undoubtedly in the future, regions which are now in a developing stage will also face the same problem. So far, related research at IIASA has been concentrated in Task 3 of the Resources and Environment Area on "Environmental Problems of Agriculture." This work has dealt in particular with agricultural-environmental processes as they are related to crop production and thus has also provided insight into the important role of agriculture in the nitrogen cycle. Yet another side of the problem remains to be considered, and this is related to water supply and management. This paper therefore proposes a study on management alternatives for control of nonpoint pollution of municipal water supply sources. The study aims at integration of the already initiated studies on "Environmental Problems of Agriculture" with IIASA's water management research. At the same time, due to the role of agriculture in this study, the study will be integrated with IIASA's Food and Agriculture Program investigations. Moreover, because of the need for modeling techniques in analyzing the problem in question, the study will utilize the research results of IIASA's activities on ecological and water quality modeling and the research pursued by the Systems and Decision Sciences Area at IIASA. Due to the importance of the problem for the majority of IIASA's National Member Organizations an international study involving IIASA and several institutions of different NMO countries is proposed. Therefore, the paper has been written in a specific form and is to be considered a tentative plan for collaboration within and outside IIASA in order to achieve more comprehensive research results. We would therefore like to ask our readers for any comments, remarks, or suggestions that could help to improve the course of our future activities

Nonpoint Nitrate Pollution of Municipal Water Supply Sources: Issues of Analysis and Control

In many developed and developing regions throughout the world, water supply and management agencies are confronted by a steadily increasing demand for water. Water supply is usually constrained by natural, technological, and economic conditions. The limit on the quantity of water which can be tapped grows more severe, because deteriorating water quality necessitates more and more complex utilization constraints. Operating with this in mind, regional water managers attempt to satisfy different supply interests, especially when these interests conflict with each other. Therefore, the competing interests of agriculture, environment, and municipal water supply become increasingly important. For example, in recent years, water supply agencies have become progressively more concerned by high nitrate levels in municipal water supply sources. In 1980, an exploratory study on "Analysis and Control of Nonpoint Nitrate Pollution on Municipal Water Supply Sources" was initiated at IIASA. The project was a collaborative effort between IIASA's Resources and Environment Area and scientific institutions in several National Member Organization countries. In concluding the project, a Task Force Meeting, bringing together experts from different fields--hydrologists, hydrogeologists, engineers, and agricultural economists--was held. The study results obtained by IIASA and the collaborative institutions was discussed in depth and topics for further research were discussed. The papers presented at this meeting are included in this volume

Enhanced bacterial decomposition with increasing addition of autochthonous to allochthonous carbon without any effect on bacterial community composition

Dissolved organic carbon (DOC) concentrations – mainly of terrestrial origin – are increasing worldwide in inland waters. Heterotrophic bacteria are the main consumers of DOC and thus determine DOC temporal dynamics and availability for higher trophic levels. Our aim was to study bacterial carbon (C) turnover with respect to DOC quantity and chemical quality using both allochthonous and autochthonous DOC sources. We incubated a natural bacterial community with allochthonous C (13C-labeled beech leachate) and increased concentrations and pulses (intermittent occurrence of organic matter input) of autochthonous C (phytoplankton lysate). We then determined bacterial C consumption, activities, and community composition together with the C flow through bacteria using stable C isotopes. The chemical analysis of single sources revealed differences in aromaticity and low- and high-molecular-weight substance fractions (LMWS and HMWS, respectively) between allochthonous and autochthonous C sources. Both DOC sources (allochthonous and autochthonous DOC) were metabolized at a high bacterial growth efficiency (BGE) around 50%. In treatments with mixed sources, rising concentrations of added autochthonous DOC resulted in a further, significant increase in bacterial DOC consumption of up to 68% when nutrients were not limiting. This rise was accompanied by a decrease in the humic substance (HS) fraction and an increase in bacterial biomass. Changes in DOC concentration and consumption in mixed treatments did not affect bacterial community composition (BCC), but BCC differed in single vs. mixed incubations. Our study highlights that DOC quantity affects bacterial C consumption but not BCC in nutrient-rich aquatic systems. BCC shifted when a mixture of allochthonous and autochthonous C was provided simultaneously to the bacterial community. Our results indicate that chemical quality rather than source of DOC per se (allochthonous vs. autochthonous) determines bacterial DOC turnover