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.     

Environmental quality assessment of Port Blair in Andaman islands

The Andman and Nicobar archipelago comprises of about 556 small and big islands covering an area of 8493 sq. kms in the Bay of Bengal. The very remoteness of these islands from the mainland has preserved their pristine environment and spectacular natural beauty. The Andman and Nicobar Administration is going for major developmental projects to cope with the increasing needs of the people, which ultimately results in significant changes in environmental quality. This paper describes the existing environmental quality around Port Blair city, which will give baseline scenario to assess the environmental impacts due to developments in the future.In order to monitor the air quality of the region, sampling stations were selected based on the locations of various industries and domestic activities. Suspended Particulate Matter (SPM), Sulphur dioxide (SO₂) and Nitrogen Oxides (NOx) were monitored for a period of one month during winter season. In addition, micrometeorological data, viz. wind speed and direction were also recorded and analysed to obtain the representative meteorological scenario of the air basin. The monitored values of ambient air quality was found to be within the NAAQ standards of India.Similarly, noise levels were also measured at various locations viz., residential areas, commercial centres, villages, stone quarry sites and construction sites. Noise levels were found to exceed the standards at stone quarry, construction sites and other locations.Water quality studies were carried out with respect to surface and ground water. The various physico- chemical and bacteriological parameters were analysed. It was observed that the physico-chemical parameters of surface and ground water lie within the standards stipulated for Indian subcontinent except for heavy metals which exceed the limits in ground water samples. Bacteriological analysis of sea water and ground water indicate that they are contaminated with faecal matters. Further, the ground water can be used for drinking purposes only after adequate treatment.     

Bakterielle Mineralisierung von Dibenzofuran,Dibenzo-p-dioxin und 1,2,4,5-Tetrachlorbenzol in Böden

Quantitative degradation of dibenzofuran (DBF), dibenzo-p-dioxin (DBD), and 1,2,4,5-tetrachlorbenzene (TeCB) by the bacterial strains sphingomonas sp. HH 69, sphingomonas sp. RW1 and pseudomonas sp. PS 14 was investigated by radio-tracer techniques in liquid cultures and especially in samples of different soils. Pure strains converted DBF, DBD and TeCB up to 80% to CO₂ within few days. This degradation occurred not only in aerated liquid cultures but also in heterogeneous soils, with low levels of other pollutatns at favourable pH-values. Rate and degree of the mineralization of DBF, DBD and TeCB were independent of the DBF-, DBD-, or TeCB-concentration in the soils within a broad range. There was obviously a close correlation between the starting concentration of active cells (starting bacterial count) and the rate of degradation of the test substances in soil; by raising the starting bacterial count in the soil samples, mineralization of DBF, DBD, and TeCB, respectively, was clearly accelerated. However, under nearly the same coniditions in more acid soils (pH-values < 4) no significant degradation of DBF, DBD, and TeCB to CO₂ took place. As expected, this difficulty can be overcome by mixing CaCO₂ into the acid soils (liming). Easily utilizable substances like peptone, triolein, and glucose added as special carbon and energy sources to low contaminated soils, had only a small—if any—effect on the mineralization of DBF, DBD, and TeCB. In soils contaminated by a mixture of pollutants, the bacterial strains could develop their degradation capacity only to a limited extent and showed different degradation effects depending on the basic type of contamination. The efficiency of the degradation specialists was thus dependent on the “Chemical Environment” (type and concentration of contaminants present).     

Growth pattern andβ-dimethylsulphoniopropionate (DMSP) content of green macroalgae at different irradiances

Growth rates and intracellular-dimethylsulphoniopropionate (DMSP) concentrations of five green algal species collected from different geographic regions in 1986 and 1989 were determined under four photon flux rates. InUlothrix implexa, U. subflaccida andAcrosiphonia arcta from Antarctica, growth was light-saturated at lower irradiances than in temperateUlva rigida from Southern Chile andBlidingia minima from Germany. The DMSP content ofUlothrix implexa, A. arcta andUlva rigida was directly correlated with the light factor: with increasing irradiance, algal DMSP level increased. In contrast, inUlothrix subflaccida andB. minima DMSP concentrations gradually decreased up to a photon flux rate of 30µmol m^–2 s^–1, then increased markedly under the highest photon flux rate tested. In non-growing, dark-incubatedA. arcta DMSP content was reduced by 35%, while the DMSP pool of all other species remained unchanged, at the level of pre-culture conditions. Under full darkness all plants exhibited a significantly higher DMSP concentration compared with algae grown at low photon flux rates of 2 to 30µmol m^–2 s^–1. These data show a correlation between growth pattern and DMSP biosynthesis, and may point to a species-specific minimum amount of light energy necessary for DMSP accumulation.Contribution no. 302 of the Alfred Wegener Institute of Polar and Marine Research