Water reservoirs are important sinks for greenhouse gases

Abstract

Water reservoirs are considered as important sources and sinks for greenhouse gases (GHG). There are limited studies that have investigated potential sinks in water reservoirs and this has led to the production of the unreal GHG budgets for water reservoirs. This study discusses the possible GHG sinks in water reservoirs, including carbon deposition in sediments, primary production in aqueous environments, induced vegetation growth in riparian zones and alternation in soil methanotrophic activity along the shoreline. Organic carbon deposition in water reservoirs is an important anthropogenic carbon sink and a substantial portion of carbon deposition is stored in sediment. The primary production of reservoirs as an important carbon sink is not well understood. Damming increases the water table and in riparian zones extends vegetation into new areas. Vegetation growth in areas that had limited plant cover may lead to higher carbon sequestration in soils. These changes in the carbon content of soils along shorelines should be considered as carbon sinks for water reservoirs. The improved methanotrophic activity in soils can be found in dry regions where severe soil moisture stress inhibits methanotrophic activity. Generally, to generate a real estimation of the GHG budget of water reservoirs, all sinks should be included in model development in future studies.