Insecticide substitutes for DDT to control mosquitoes may be causes of several diseases

Malaria continues to be a public health problem in Bangladesh, despite efforts in the 1960s to eradicate the vectors through the use of DDT. At one point, eradication of malaria was acclaimed but later on it reappeared. The use of DDT is no more legally allowed in Bangladesh, which has been officially replaced by a number organophosphates and/or synthetic pyrethroids and their combinations in addition to the integrated vector management (IVM) package. IVM being a community approach is still to go a long way to be mass popular. Adulticides, larvicides, residual sprays, mosquito coil, insecticide-impregnated curtain, aerosol, etc. still serve as the major weapons of mosquito control. Thus, mosquito control still mostly depends on chemical insecticides. Although the use of DDT is banned in Bangladesh, there are reports on its illegal use in different forms. Moreover, there is tons of leftover DDT in Bangladesh, which is likely to cause several diseases. As per one report, about 500 MTs of DDT stockpiles are lying in the Medical Sub-Depots at Chittagong for over a period of 26 years. DDT is a persistent organic pollutant pesticide, which can cause diseases like cancer, endocrine disorder, disruption of immune system, embryonic abnormality, reproductive disorder, etc. Other chemical insecticides, which are replacing DDT, are also not free of hazardous impacts. IVM thus appears to be a wise approach requiring concerted efforts for the management of mosquito to control malaria. Such an IVM comprises use of Bacillus thuringiensis Berliner var. israelensis, methoprene, biocontrol agents, cleaning of breeding sites, pyrethroid-impregnated curtain, etc. Therefore, a wise effort should be adopted to completely stop the use of DDT, eliminate its stockpiles wherever they are in Bangladesh and to popularise the IVM, not the chemicals-based alternatives throughout the country.     

Soil erosion hazard evaluation—An integrated use of remote sensing,GIS and statistical approaches with biophysical parameters towards management strategies

Soil erosion hazard maps can be an essential tool in erosion prone areas as they explain and display the distribution of hazards and areas likely to be affected to different magnitudes. Therefore, it is very useful to planners and policy makers initiating remedial measures and for prioritizing areas. In this study, a numerical model was developed for soil erosion hazard assessment, in which Z-score analysis was combined with a geographical information system (GIS) to compute a synthetic soil erosion hazard index (SEHI). For this model, nine factors which have notable impact on soil erosion were selected. To generate the selected factors remote sensing, analytical hierarchy process (AHP) and GIS techniques along with spatial models were applied. To standardize all of the factors and establish the factor weights, the AHP method was adopted. For Z-score analysis with selected standardized factors, the Integrated Land and Water Information System (ILWIS) software was used and nine individual layers with Z-scores were prepared. Afterwards, the layers were integrated with their factor weights by means of a weighted linear combination to derive a SEHI value for each pixel. To classify the discrete SEHI map to represent a meaningful regionalization of soil erosion hazard, the equal distance cluster principle was used and graded into four levels of hazard; very high, high, moderate and low. The results depicted that in general, a moderate hazardous condition of soil erosion was found in the study area and the proposed approach was also able to identify the areas under high and very high hazards that require urgent intervention on a priority basis. Based on this study, comprehensive erosion hazard management strategies were anticipated for the efficient management of present and future erosion disaster in the area.     

利用水浮莲净化麻黄素厂污水的中试研究

将麻黄素厂污水稀释5倍在100m2池面的水浮莲净化塘内进行了净化处理.在滞留处理时间为9d的条件下,SS、BOD₅、COD_Cr、NH₄^-N与色度的去除率分别保持在80.94%,89.43％,76.28％,88.51％,84.64%以上,净化水的理化指标达到了二级排放标准.细菌总数与大肠杆菌群数的剩余率也仅为净化前的0.238％和0.129％.蚕豆根尖微核检测结果表明致突变污染指数PI由净化处理前的6.02(6.44降到2.95以下.     

Transfer of radiocobalt from soil to selected plant species in tropical environments

Soil-to-plant transfer factors (TFs) of radiocobalt (60Co) were determined in pot experiments for leafy vegetation, root crops and rice grown in the tropical environment of Bangladesh. Soil properties were also measured to establish a relationship between these properties and TF values. Measured TF values of 60Co for leafy vegetation (average of 2.2 x 10(-2)) were slightly higher than the values obtained for root vegetation (average of 1.6 x 10(-2)). However, TF values obtained for rice (average of 1.17 x 10(-2)) were about a factor of 2 lower than the values obtained for leafy vegetation. TF values of 60Co for leafy vegetation and root crops were observed to decrease with increasing pH, exchangeable K+ and clay content in the soil, even though poor correlations were estimated statistically. No consistent relationship between the TF value for 60Co and organic matter content could be deduced. The results presented here provide a useful addition to existing databases on soil-plant transfer for 60Co, since this information is still rather sparse for tropical environments.     

Assessing of Environmental Quality in Six Areas in India,Sri Lanka and Bangladesh

Environmental quality for environmental health has been examined visually by describing general conditions and drinking water supply, sanitation and solid waste treatment conditions and practices in six South-East Asian villages with a dense population. The environmental review was supplemented by discussions with local people and political and administrative decision makers. Some drinking water analyses were done in order to show the water quality to the local people. The quality of the general conditions and the conditions and practices of drinking water supply, excreta disposal and solid waste treatment practices have been graded with the grading system presented below. The grading could be done in 1 or 2 days in each area by two persons, of which one was an environmental scientist and the other a social scientist, who also knew the local culture and worked as a translator.     

Infant and Under-five Mortality in Bangladesh: Discriminant Analysis

Abstract

Bangladesh is on target for achieving the Millennium Development Goal 4 relating to infant and under-five mortality because of very rapid reduction in mortality in recent years. But this rate of reduction may be difficult to sustain and may hamper the achievement of Millennium Development Goal 4. Therefore, the main objective of this paper is to discuss and compare the different covariates of infant and under-five mortality in the context of overall country, urban and rural levels of Bangladesh using discriminant analysis. For this, the data are taken from Bangladesh Demographic and Health Survey, 2004. In discriminant analysis, the stepwise procedure has been picked up and only the significant variables are ranked according to the rank of Wilk’s Lambda values. The canonical discriminant function coefficients (unstandardized and standardized) for the predictor variables have also been calculated. Both the results show that breastfeeding is the most important variable in discriminating the two groups of mothers, i.e., mothers experiencing to infant mortality or not and mothers experiencing to under-five mortality or not. The related results of discriminant function also indicate that the discriminant function is statistically significant and discriminates well. Therefore, improvements in the health system are essential for promoting the breastfeeding practices (both inclusive and exclusive), which may be the effective strategies to reach families and communities with targeted messages and information.     

Radon exhalation from building materials for decorative use

Long-term exposure to radon increases the risk of developing lung cancer. There is considerable public concern about radon exhalation from building materials and the contribution to indoor radon levels. To address this concern, radon exhalation rates were determined for 53 different samples of drywall, tile and granite available on the Canadian market for interior home decoration. The radon exhalation rates ranged from non-detectable to 312 Bq m⁻² d⁻¹. Slate tiles and granite slabs had relatively higher radon exhalation rates than other decorative materials, such as ceramic or porcelain tiles. The average radon exhalation rates were 30 Bq m⁻² d⁻¹ for slate tiles and 42 Bq m⁻² d⁻¹ for granite slabs of various types and origins. Analysis showed that even if an entire floor was covered with a material having a radon exhalation rate of 300 Bq m⁻² d⁻¹, it would contribute only 18 Bq m⁻³ to a tightly sealed house with an air exchange rate of 0.3 per hour. Generally speaking, building materials used in home decoration make no significant contribution to indoor radon for a house with adequate air exchange.     

Radiocaesium soil-to-plant transfer in tropical environments

In this work, soil-to-plant transfer factors of radiocaesium are predicted based on soil properties such as pH, organic matter content, exchangeable K+ and clay content valid for the tropical environments in Bangladesh, China and Japan, and using a previously published model. Due to insufficient data of soil properties in the selected regions, the average values of pH, organic matter content, exchangeable K+ and clay content were taken as the input model parameters within the ranges given for Asia. Nevertheless, a complete set of soil properties of Japanese soils was used to compare the measured and calculated TF values of radiocaesium for radish. The calculated TF values for radiocaesium are comparable with the measured values especially for leafy parts of a plant. However, calculated values for rice, an important crop in Asia are found to overestimate the measured values due to an overestimate of calculated CECs in soils in the selected regions. The empirical parameters used in the model need to be re-evaluated for the specific part of a plant and/or for a variety of different plants. Alternatively, a general conversion factor for each part of a plant and/or for a variety of different plants for a specific region is suggested for tropical environments.     

Geo-based model of intrinsic resilience to climate change: an approach to nature-based solution

A substantial amount of researches have been done on the understanding and assessment of resilience from multiple perspectives, e.g., ecological, social, economic, and disaster management; however, recent international approach is trending toward more systematic and comprehensive risk assessment processes. Pivotal element of such approach is to emphasizing on promoting resilience in the face of climate change impacts. Conceptualization and identification of parameters to assess climate change resilience is one of the remaining challenges that academia is facing. Reviewing the principles of the climate change resilience highlighted in the literature, the goal of this study is to introduce a theoretical model about the climate change resilience concept to facilitate and enhance future climate change resilience-related researches. The model proposed in this study is named as the climate change resilience of place (C-CROP) model, a geo-based model which is designed to assess climate change resilience for any geographic region with an approach to the incorporation of nature-based solution (NBS). C-CROP model considers vulnerability, exposure, sensitivity to climate change on one side; another side is co-benefit, climate proofing, and disservices of proposed NBS. An operational framework of the C-CROP model is also proposed, that allows spatially explicit assessment of climate change resilience in real world by developing an indicator-based framework and comprehensive mapping using the geospatial approach. Therefore, this model includes vulnerability hotspots identification; better understanding of the pathways of resilience; and solutions (i.e., NBS) to infer the impacts and effectiveness of resilience-building interventions.

     

Dissipation of the herbicide clopyralid in an allophanic soil: laboratory and field studies

Soil dissipation of the herbicide clopyralid (3,6-dichloropicolinic acid) was measured in laboratory incubations and in field plots under different management regimes. In laboratory studies, soil was spiked with commercial grade liquid formulation of clopyralid (Versatill, 300 g a.i. L(-1) soluble concentrate) @ 0.8 microg a.i. g(-1) dry soil and the soil water content was maintained at 60% of water holding capacity of the soil. Treatments included incubation at 10 degrees C, 20 degrees C, 30 degrees C, day/night cycles (25/15 degrees C) and sterilized soil (20 degrees C). Furthermore, a field study was conducted at the Waikato Research Orchard near Hamilton, New Zealand starting in November 2000 to measure dissipation rates of clopyralid under differing agricultural situations. The management regimes were: permanent pasture, permanent pasture shielded from direct sunlight, bare ground, and bare ground shielded from direct sunlight. Clopyralid was sprayed in dilute solution @ 600 g a.i. ha(-1) on to field plots. Herbicide residue concentrations in soil samples taken at regular intervals after application were determined by gas chromatograph with electron capture detector. The laboratory experiments showed that dissipation rate of clopyralid was markedly faster in non-sterilized soil (20 degrees C), with a half-life (t1/2) of 7.3 d, than in sterilized soil (20 degrees C) with t1/2 of 57.8 d, demonstrating the importance of micro-organisms in the breakdown process. Higher temperatures led to more rapid dissipation of clopyralid (t1/2, 4.1 d at 30 degrees C vs 46.2 d at 10 degrees C). Dissipation was also faster in the day/night (25/15 degrees C) treatment (t1/2, 5.4 d), which could be partly due to activation of soil microbes by temperature fluctuations. In the field experiment, decomposition of clopyralid was much slower in the shaded plots under pasture (t1/2, 71.5 d) and bare ground (t1/2, 23.9 d) than in the unshaded pasture (t1/2, 5.0 d) and bare ground plots (t1/2, 12.9 d). These studies suggest that environmental factors such as temperature, soil water content, shading, and different management practices would have considerable influence on rate of clopyralid dissipation.