Quantification of water purification in South African palmiet wetlands

Abstract

Despite the importance of water purification to society, it is one of the more difficult wetland ecosystem services to quantify. It remains an issue in ecosystem service assessments where rapid estimates are needed, and poor-quality indicators are overused. We attempted to quantify the water purification service of South African palmiet wetlands (valley-bottom peatlands highly threatened by agriculture). First, we used an instantaneous catchment-scale mass balance sampling approach, which compared the fate of various water quality parameters over degraded and pristine sections of palmiet wetlands. We found that pristine palmiet wetlands acted as a sink for water, major cations, anions, dissolved silicon and nutrients, though there was relatively high variation in these trends. There are important limitations to this catchment-scale approach, including the fact that at this large scale there are multiple mechanisms (internal wetland processes as well as external inputs) at work that are impossible to untangle with limited data. Therefore, secondly, we performed a small field-scale field survey of a wetland fragment to corroborate the catchment-scale results. There was a reasonable level of agreement between the results of the two techniques. We conclude that it appears possible to estimate the water purification function of these valley-bottom wetlands using this catchment-scale approach.

Ecosystem services provided by South African palmiet wetlands: A case for investment in strategic water source areas

“…One simple way to estimate wetland water quality regulation, is to estimate the nitrogen and phosphorus uptake rates across a stretch of wetland using opportunistic sampling locations (preferential flow paths through the wetlands, or gullies). Mean nitrogen and phosphorus uptake were estimated, as well as efficiency (%) in degraded and pristine sections of these three palmiet wetlands (Rebelo et al, 2018;Rebelo, 2017; Table 3). Nutrient uptake efficiency was calculated by taking the percentage of the amount of nutrients leaving the wetland from the amount entering the wetland.…”

Comparison and interpretation of freshwater bacterial structure and interactions with organic to nutrient imbalances in restored wetlands

“…Great efforts have long been made to conserve, restore, and construct wetlands because of the important functions and services provided by these ecosystems, including water purification, environmental improvement, and biodiversity maintenance ( Rebelo et al, 2018 ; Sampaio et al, 2018 ; Chen et al, 2019 ). Previous studies mainly focused on meeting water index standards based on wetland restoration technology and decreasing the water nutritional index, which is closely related to the interactions between microbes in the aquatic environment ( Cardinale, 2011 ; Brisson et al, 2020 ; Garibay et al, 2021 ).…”