Modelling the spatial distribution of ammonia emissions from seabirds in the UK

Knowledge of the sources and distribution of ammonia (NH3) emissions underpins our understanding of the nitrogen budget. Research has focused on quantifying NH3 emissions from anthropogenic sources, whilst those from natural sources have received little attention internationally. Seabirds excrete large quantities of nitrogen, making seabird colonies a major natural source of NH3. Ammonia emissions from each UK seabird species were estimated and combined with population distribution data to model their spatial distribution. Total NH3 emissions from UK seabirds were estimated at 2.7 kt per year. Seabird emissions are concentrated in remote parts of the UK where anthropogenic emissions are small, so that seabirds often represent the main source of NH3 emissions in these areas. Seabird NH3 emissions were found to have increased by 34% since the 1970s. This corresponds to population changes which may be influenced by human activities, showing that even this natural source can be anthropogenically modified.     

Computer software tool REALM for sustainable water allocation and management

REALM (REsource ALlocation Model) is a generalised computer simulation package that models harvesting and bulk distribution of water resources within a water supply system. It is a modeling tool, which can be applied to develop specific water allocation models. Like other water resource simulation software tools, REALM uses mass-balance accounting at nodes, while the movement of water within carriers is subject to capacity constraints. It uses a fast network linear programming algorithm to optimise the water allocation within the network during each simulation time step, in accordance with user-defined operating rules. This paper describes the main features of REALM and provides potential users with an appreciation of its capabilities. In particular, it describes two case studies covering major urban and rural water supply systems. These case studies illustrate REALM's capabilities in the use of stochastically generated data in water supply planning and management, modelling of environmental flows, and assessing security of supply issues.     

Solid Waste Management Practices in the Eastern Province of Saudi Arabia

Solid waste management practices in the Eastern Province of Saudi Arabia are reviewed. The officials of various municipalities and agencies responsible for collecting and disposing of municipal waste were interviewed. The refuse generation rate found is in the range of 1.61–2.72 kg per capita per day. The refuse composition data indicate a high percentage of glass, metals, and wood. For storage purposes, 0.2-m³ barrels are used in residential areas and 0.75 to 1.50 m³-capacity containers are used in commerical areas. The present solid-waste collection system is labor-intensive, and a significant part of the budget is spent on collection and haul operations. The unit collection and haul cost is much higher than the unit disposal cost of refuse. The direct haul of refuse is the common practice, and the use of transfer stations has not yet been considered. It is also observed that the disposal methods used at these sites are not in line with modern techniques for refuse disposal. Landfilling and combined burning and landfilling are the common disposal methods at all the sites.     

WELFARE IMPLICATIONS OF TUBEWELL IRRIGATION IN BANGLADESH1

ABSTRACT: This paper investigates and estimates the welfare loss due to monopoly in tubewell irrigation water market in Bangladesh. In this context, an attempt has been made to evaluate the efficacy of the landless irrigation groups. Using cross-sectional data and regression analysis, cost and demand functions for irrigation water are estimated. The study demonstrates the relatively superior performance of the landless groups in terms of economic efficiency in shallow tubewell irrigation operation, in comparison to irrigation operation by the landowners.     

Methane in ocean waters: Concentration and carbon isotope variability at East Pacific Rise and in the Arabian Sea

Methane concentrations and stable carbon isotope ratios of water samples from the East Pacific Rise (EPR) at 21°S and the Arabian Sea (24°N, 65°E) have been determined. EPR surface water is in equilibrium (ca. 50 nl/L and –50<¹³CH₄<–46) with atmospheric methane. Deep background water has the signature of the remaining fraction of atmospheric methane partially oxidized in the water column by bacteria. Bottom near, hydrothermally influenced vent methane (>100nl/L and –30<¹³CH₄<–22) is detectable only close to the seep site. There is no input of hydrothermal methane into the atmosphere. EPR water is considered to be rather a sink than a source of atmospheric methane. Surface waters of the Arabian Sea are enriched in methane relative to the atmosphere (source for atmospheric methane). Carbon isotope ratios point to a bacterial origin of methane (¹³CH₄<–55) that is generated in the surface waters. Concentration changes and variations of carbon isotope ratios also suggest that methane seeping from the sea floor sediments of the Arabian Sea is oxidized by bacterial activity and does not reach the atmosphere.     

Monitoring Studies of Augusta Bay Marine Waters

The monitoring of water quality today provides a great quantity of data consisting of the values of the parameters measured as a tunction of bme or as spatial function.In the marine environment, and especially in the suspended material, increasing importance is being given to the presence of particular pollution indices. With the increase in the number of sampling points, the amount of data increases and examining the results and their consequent interpretation becomes more difficult. To overcome such difficulties, numerous chemometric techniques have been introduced in environmental chemistry, such as Principal Component Analysis (PCA).The use of the PCA in this work has been applied to the analysis of twenty three different sampling points in three seasonal sampling cruises in the same year. This led to recognition of the influence and the localisation of wastewaters in the Augusta bay after measuring the water pollution parameters.The PCA made evident the difference between some sampling sites whose data were initially thought to be similar where the presence of hot industrial water discharge or urban wastewater determines the permanent water quality.Furthermore, it has allowed a choice of more significant parameters for monitoring programs and more representative sampling site locations.     

Detection of Methamidophos in Vegetables Using a Photometric Flow Injection System

A flow injection analysis (FIA) system using immobilized acetylcholinesterase (AChE) has been used for the detection of methamidophos in vegetable extracts. Methamidophos is one of the most commonly used organophosphate insecticides in South East Asia. AChE was immobilized onto magnetic particles; using a magnetic reactor, the particles could easily be separated from the test sample. Results show that complex matrices such as vegetable extracts have no inhibitory effect on AChE activity in the FIA system. The presence of methamidophos in the extracts caused AChE inhibition. The response could be followed as an inhibition curve and the inhibition constant calculated. Results show that using 85% AChE residual activity as the detection limit, methamidophos could be detected in lettuce and cabbage at 12 and 3 mg/kg vegetable material respectively. In a simulated field situation, cabbage leaves were spiked with 20 to 40 mg/kg methamidophos, homogenized and tested in the FIA system. The corresponding methamidophos levels predicted by the experimental results came very close to the known calculated values. Data presented here suggest that it is feasible to use this system to supplement the traditional chromatographic analysis methods for methamidophos analysis.