Microplastic accumulation in endorheic river basins - The example of the Okavango Panhandle (Botswana).

The Okavango Panhandle is the main influent watercourse of the Okavango Delta, an inland sink of the entire sediment load of the Cubango-Okavango River Basin (CORB). The sources of pollution in the CORB, and other endorheic basins, are largely understudied when compared to exorheic systems and the world's oceans. We present the first study of the distribution of microplastic (MP) pollution in surface sediments of the Okavango Panhandle in Northern Botswana.

Phenology is the dominant control of methane emissions in a tropical non-forested wetland.

Tropical wetlands are a significant source of atmospheric methane (CH), but their importance to the global CH budget is uncertain due to a paucity of direct observations. Net wetland emissions result from complex interactions and co-variation between microbial production and oxidation in the soil, and transport to the atmosphere. Here we show that phenology is the overarching control of net CH emissions to the atmosphere from a permanent, vegetated tropical swamp in the Okavango Delta, Botswana, and we find that vegetative processes modulate net CH emissions at sub-daily to inter-annual timescales.

From sink to source: high inter-annual variability in the carbon budget of a Southern African wetland.

We report on three years of continuous monitoring of carbon dioxide (CO) and methane (CH) emissions in two contrasting wetland areas of the Okavango Delta, Botswana: a perennial swamp and a seasonal floodplain. The hydrographic zones of the Okavango Delta possess distinct attributes (e.g.

Methane flux measurements along a floodplain soil moisture gradient in the Okavango Delta, Botswana.

Data-poor tropical wetlands constitute an important source of atmospheric CH in the world. We studied CH fluxes using closed chambers along a soil moisture gradient in a tropical seasonal swamp in the Okavango Delta, Botswana, the sixth largest tropical wetland in the world. The objective of the study was to assess net CH fluxes and controlling environmental factors in the Delta's seasonal floodplains.

Low oxygen: A (tough) way of life for Okavango fishes.

Botswana's Okavango Delta is a World Heritage Site and biodiverse wilderness. In 2016-2018, following arrival of the annual flood of rainwater from Angola's highlands, and using continuous oxygen logging, we documented profound aquatic hypoxia that persisted for 3.5 to 5 months in the river channel.

Sap flow variation in selected riparian woodland species in the Okavango Delta, Botswana.

In the tropical Okavango Delta, transpiration by trees is an important process partly responsible for maintaining the basin as a freshwater environment. Quantification of evapotranspiration from terrestrial landforms of the delta, fringed by riparian woodlands, is one of the main contributors to uncertainty in current hydrological modelling. We investigated sap flow of common trees in the distal, mid- and upper delta in July-August 2012, November-December 2012 and February-April 2013 using the compensation heat pulse velocity method.

Input, behaviour and distribution of multiple elements in abiotic matrices along a transect within the Okavango Delta, northern Botswana.

Wetlands fed by rivers can be a sink for elements depending on elemental concentrations, wetland hydrology, geochemistry, vegetation and climate. In the case of the Okavango Delta, northern Botswana, the outflow discharge is a small fraction (2-5%) of the inflow. This has strong potential consequences for the Delta, as it strongly affects element cycling and storage within the Delta.