Invention on Correlation between the chemical composition of the surface sediment and water in the mangrove forest of the Sundarbans, Bangladesh, and the regeneration, growth and dieback of the forest trees and people health

摘要

Sundarbans in Bangladesh has been facing tremendous environmental pollution problems, including that of dieback (top-dying) of the main tree species (Heritiera fomes), and also various health hazards among the surrounding people in Sundarbans, Bangladesh, which is affecting millions of trees and people in Sundarbans areas (Awal, M.A. 2007). The cause of this dieback and health hazard is unknown. The present work has investigated one of the possible factors that might be causing this top-dying, namely the concentrations of various chemical elements present in the sediments, particularly heavy metals, though other chemical parameters such as the pH, salinity, moisture content of the sediment and nutrient status were also assessed. Tree height and trunk diameter were determined as indications of tree growth, counts of seedlings and saplings were made to assess regeneration success, and the intensity of top-dying within the sampled plots was recorded on a rank scale. In order to establish the views of local people about the incidence and causes of top-dying and health hazard, a questionnaire was prepared for asking peoples either individually or in groups. This survey was done among people living or working in the 17 Sub-Districts of Sundarbans, making a distinction between those living within and outside of Sundarbans. So, this survey was performed to receive their indigenous response and knowledge towards top dying, and its present conditions, and their ideas about what leads to top-dying, as well as questions about tree regeneration and human health in Sundarbans. As well as seeking evidence about the health status of the Sundarbans, the questionnaire attempted to assess whether there were increasing health issues for the local people resident in the area of Sundarbans. According to the people thought that several human health problems are present among the neighbouring peoples of Sundarbans areas. These included particularly skin irritation, black spots on organs of their bodies such as hands and on arms, as well as spots on their faces, dysentry and diarrhoea, and cholera problems. They thought that excessive abnormal concentrations of metals, with Arsenic being particularly mentioned and also excessive salinity, were responsible for these diseases.