Characterisation and Description of Surface Water Quality in the Threatened Urban Wetlands around the City of Colombo

Abstract

Colombo is a city surrounded by a large and interconnected system of natural wetlands. These wetlands which have historically provided a range of water services to the city are now believed to be threatened by degradation due to the recent changes in the urbanization patterns and urban lifestyle in Colombo. This paper presents a study on the current state and recent trends in surface water quality in a selected segment of these wetlands. The study was carried out as a part of a broader multidisciplinary research. The paper consists of a historical analysis of trends in surface water quality parameters and situation analysis of short term spatial and temporal water quality variation in the study area. The research identified that water quality parameters indicating domestic wastewater related pollution showed an increasing trend during the study period. BOD, Phosphates and Fecal Coliform were recorded in levels exceeding the accepted ambient water quality standards. Concentrations of several heavy metals were also above the ambient water quality standards. A distinct difference was observed in water quality between peripheral areas and internal water ways of the wetland. All evidence directs towards severe water quality degradation in the wetland dominated by domestic waste discharges and scattered solid waste dumps. This condition may lead to a nutrient enrichment of the wetland and cause biological and physical responses that may affect adversely on the water services provided.

Heavy metal mediated immunomodulation of the Indian green frog, Euphlyctis hexadactylus (Anura:Ranidae) in urban wetlands

“…In Sri Lanka, urbanization has caused a steady degradation of urban wetlands during the past few decades (CEA, 1994;Hettiarachchi et al, 2011), threatening the sustainability of ecosystem services provided. Heavy metals disposed of through industrial and domestic wastes and effluents are amongst the most ubiquitous pollutants, posing severe threats to biota in the wetland ecosystems (Rai, 2009).…”

Governing the urban wetlands: a multiple case-study of policy, institutions and reference points

“…Most effective wetlands policies (for example the Wadden Sea Plan; Common Wadden Sea Secretariat 2010) in post-industrial countries were achieved through convoluted local-level bargaining processes among stakeholders. Furthermore, recent wetland policies in developing countries that superficially follow Ramsar guidelines, are often criticized as normative and superfluous (Panini 1998;Hettiarachchi et al 2011). The only urban specific policy directive adopted by Ramsar is resolution X.27 brought in at the 10th Conferences of the Parties in Korea (Ramsar 2008).…”

“…Many scholars have questioned the effectiveness of setting common reference points for governing both urban and rural wetlands (Ehrenfeld 2000;Santlemann & Larson 2004;Hettiarachchi et al 2011). Urban wetlands of a given wetland type (or class) are subtly different in ecological character from those of the same type in rural and natural settings (Ehrenfeld 2000(Ehrenfeld , 2004Kentula et al 2004).…”

“…In 1928, under the Colombo Flood Protection Plan of the Irrigation Department of Ceylon, this wetland was designated as the main flood-detention basin and intensely engineered for this purpose (CEA 1994). The entire focus of management became flood control, and other wetland uses (agriculture and fishing) began to wither (Hettiarachchi et al 2011). In 1968, the SLLRDC was instituted by a national act to manage the wetlands around Colombo.…”

“…Internationally, the Ramsar Convention of 1971 (http://www.ramsar.org) was the most important landmark in formally institutionalizing wetland management and conservation actions across the world (Gopal 2003;Mitsch & Gosselink 2007;Smardon 2009). Initially, the Convention Table 1 Key milestones in transnational and national level wetland policy after Ramsar (Sources: Lewis 2001;Bowman 2002;Smardon 2009;Ramsar Convention Secretariat 2006;Common Wadden Sea Secretariat 2010;Hettiarachchi et al 2011). [1975][1976][1977][1978][1979][1980] European Commission Directive on the conservation of wild birds had a conservation focus and was primarily concerned with assisting the contracting parties to identify and protect the 'Wetlands of International Importance'.…”