Contaminated sediments might directly or indirectly affect fishery products which we consume daily. Therefore, it’s required to take adequate measures to manage sediments properly. The Environmental Protection Administration (EPA) of the Executive Yuan had declared some regulations to manage qualities of sediments 2010, and had requested the competent authorities to detect and report sediments quality data for further reference. In order to make clear of sediment quality in Taiwan, it is necessary to perform the investigations in the down streams with the poor water quality and high frequency of popular activities and the specific water bodies for fish breeding and predation.
In this project, the main works and major accomplishments were (1) to collect and analyze the sediment quality and water quality data, water pollutant discharge quantity data and human activity (leisure and fish farming) information of the nationwide river bodies so as to get a comprehensive understanding and a priority on high risk river bodies, (2) to develop an assessment method of pollution potential and the staging investigation strategies of sediment in river bodies considering receptor exposure and food safety, (3) to conduct the investigations of water borne media for the pollution potential in probing sediment quality, and (4) to develop the operating procedure and executing strategies of risk assessment and management for controlling the sediment quality.
The survey and ivestigation of the water bodies of the 14 high pollution potential rivers and 20 river mouth areas along the west coast of Taiwan were carried out. Results show that 8 rivers have pollutant concentrations in sediment higher than the upper limits of sediment guideline and water quality of some rivers exceeds the baseline value for protecting human environment. In the meanwhile, most river mouths commonly have nickel concentrations between the lower limit and the upper limit.
In order to assist EPA to collecting information of sediment quality and promoting administrative controls, this project also clarified major polluted river sections and possible sources of polluted rivers with high pollution potential, mostly caused by sewage discharge from upstream businesses or industrial areas. Therefore, water pollution reduction and water quality improvement management are still recommended, and the executive measures include strengthening business inspection and punishment, strengthening guidance on pollution reduction for upstream stations and industrial areas. According to the basic characteristics of water bodies, water quality and sediment quality data, comprehensive assessment and establishment of pollution potential and quality management grading benchmark of waterbodies were also accomplished.
According to the classification system of sediment management for water bodies, 16 rivers are classified as high concern and 20 rivers are classified as moderate concern. They should comply with the regulations on sediment restrictions. If there is a risk of affecting human health, it is recommended to carry out supplementary investigations of recreation areas, hazard assessment and research and protection measures; 12 irrigation channels are classified as high concerned and should implement measures to strengthened management; 91 reservoirs should be management by following the current regulations for water bodies and sediment.
By collecting foreign literature and administrative documents of sediment quality management, this project drafted a hazard assessment method of sediment pollutants. The experimental research was also performed in Wang Gong and Qi Gu to realize the bioaccumulation in sediment and benthic organism. Results show no potential for human health and environmental pollution in the two oyster breeding areas. Based on the accomplishments of this project, sustainable survey of polluted areas in the future is proposed so as to promote comprehensive and sound environmental management.