Assessment of Plastic Waste Accumulation in the Densu Delta Ramsar Site in Ghana: A Dpsir Approach

Abstract

Ramsar sites, wetlands of international importance under the Ramsar Convention, provide numerous benefits such as flood and climate control, water storage and purification and serve as the habitat for native and migratory water birds. However, the sustainability of Ramsar sites is threatened by their high susceptibility to plastic waste accumulation. This study assessed the trend of macroplastic and microplastic accumulation in the Densu Delta Ramsar Site in Ghana, and investigated the perceptions of key stakeholders on plastic waste accumulation using the drivers, pressures (i.e. anthropogenic activities), state, impacts and response (DPSIR) approach. Macroplastic and microplastic accumulation was investigated at three (3) sampling locations in the Ramsar site: Panbros, Tsokome and Densu Estuary. Macroplastic litter monitoring surveys were undertaken within established transects along the bank of the Densu River at the three (3) sampling locations over a three (3)-month period spanning August to October, 2023. For microplastic accumulation assessment, sediment core samples were taken from the three (3) locations and subjected to laboratory analysis to examine their microplastic content while the age determination of the sediment cores was carried out through the deployment of sediment traps. Perception assessment was carried out using questionnaires administered to 397 persons living and/or working within the catchment of the Ramsar site while semi-structured interviews were conducted with six (6) institutions in charge of the protection of the Ramsar site. Across all locations, the total macroplastic litter abundance ranged between 762 to 1908 macroplastic items while total microplastic abundance ranged between 267 to 304. The Densu Estuary sampling location recorded the highest abundance for both macroplastics and microplastics across the three (3) locations, reflecting its status as a hotspot for plastic waste accumulation. The historical trend in microplastic accumulation in the Ramsar site revealed a largely growing abundance from 1975 to 2023, corresponding with the growth in plastic consumption in Ghana from the 1970s to date. Results of the social assessment indicated that the main drivers of plastic waste accumulation are population growth and economic growth associated with the needs for shelter and income respectively, while the main perceived pressures included urban growth activities, petty trading and fishing. The state of plastic waste accumulation was also perceived to be on the rise. Perceived impacts included reduction in the tourism potential of the Ramsar site, adverse impacts on livelihoods such as fishing and reduction in water quality. Key among the response measures suggested by stakeholders included the banning of single-use plastics, attitudinal change towards plastic waste management and provision of waste bins. Recommendations of this study include the phasing out of specific single-use plastics such as plastic carrier bags in Ghana and their replacement with environmentally-friendly alternatives such as paper bags and jute bags. There also needs to be curtailment of plastic importation and the establishment of plastic buy-back centres within the catchment of the Ramsar site and in upstream areas by the government to encourage recycling. Additionally, there should be the strict enforcement of the waste management provisions of the Wetlands (Ramsar Sites) Management Regulations (L. I. 1659) by the government and attitudinal change on the part of persons within the Ramsar site and in upstream areas.