MITIGATION OF EUTROPHIC ENVIRONMENTS THROUGH GEOENGINEERING USING NATURAL ADSORBENTS FROM SEMI-ARID
Restoration of lakes. Phosphorus. Internal fertilization. Capping.
Eutrophication is a natural process that consists of increasing primary productivity due to excessive nutrient enrichment. The effects of this process impact the decrease in water quality and the economy. In addition to the external sources of nutrients, it is essential to control the internal sources of matches to mitigate the effects of eutrophication. Phosphorus is considered the limiting nutrient for eutrophication, therefore, it requires interventions in its biogeochemical cycle. The “flock and lock” geoengineering technique reduces the resuspension of phosphorus from the sediments and helps to remove dissolved and particulate phosphorus in the water column, combining dosages of flocculants with a solid phosphorous adsorbent material, which can be natural or not. Among the most widely used adsorbents, Lanthanum Modified Bentonite (BML) has better efficiency, but its high cost makes it impossible to apply this technique on a full scale. Natural materials are promising as alternatives to solid phase adsorbents in the restoration of eutrophic aquatic environments. The objective of this work is to test the efficiency of geoengineering using natural adsorbents from the semiarid to control algal blooms and internal fertilization in eutrophic reservoirs in the Brazilian semiarid, through phosphorus adsorption experiments with the natural adsorbents from the semiarid: Fine waste from the scheelite mining in Currais Novos; Planossolo of Santa Cruz and Luvissolo Chromic of Cruzeta, with water from potiguares reservoirs: Gargalheiras, Boqueirão, Cruzeta and Dourado, in addition to internal fertilization control experiments, operating flock and lock experiments using the natural adsorbent in the water and sediment of the reservoir in the semi-arid region that obtain the best result in the adsorption test. The sediment characterization will be done through a sequential chemical extraction known as fractionation.