Properties and Transport of Organic Matter from the Inland to the Ocean - Influence of Coastal Wetlands.

Abstract

Summary To assess the influence of sub-tropical coastal wetlands on organic matter transport by rivers in southeastern Africa we conducted a multi-timescale study by characterising the current status, the recent past (∼2000years), and the time since the formation (∼6000 years) of South Africa's largest Freshwater Wetland System (MKhuze Wetland System, KwaZulu Natal). This approach and the application of multiple proxies such as plant-wax derived n-alkanes, their compound specific isotope composition, bulk organic matter parameters, Rock-Eval analyses, and persistent organic pollutant quantification enable us to decipher the three main drivers which can cause alteration in biomarker signals: (i) natural development of the system, (ii) adaptation/response to climatic events, and (iii), especially during the Late Holocene, anthropogenically induced changes. The combination of the present status (predominant vegetation, organic matter transport pathways and characteristics) with the decadally resolved records and a centennial archive promise to provide a comprehensive clarification of the evolution of a subtropical wetland in a coastal watershed and its response to climatic conditions.