Texto completo. Acesso restrito. p. 887–894The rehabilitation of a pond after approximately 20 years of strong acidified conditions due to industrial
and domestic waste deposition in its catchment basin is reviewed. We describe in this study the acidification
process that occurred in a tropical pond in Northeast Brazil (Dunas Lake), the rehabilitation plan
for the pond and the subsequent monitoring conducted over two decades. After the contamination
assessment by the late 80s, a rehabilitation plan was carried out in the early 90s, in which the contaminated
soil and water have been removed and reduced, respectively. No further attempt to neutralize the
water or any remediation has been carried out. A toxicity monitoring plan based on toxicity assays with
the fish Poecilia reticulata was employed to verify the natural rehabilitation of the pond. The data on toxicity,
pH, conductivity, sulphate and dissolved iron recorded from 1994 to 2010 were also compiled and
discussed. The collected data in 2003 and 2004 indicated changes in water quality and from them complementary
management actions, namely improvement in the containment plant, were conducted in
2005. Results for toxicity assays and pH results indicated interannual changes in the water quality similar
to rainy-dry periods. Moving average approach using pH data clearly showed the recovery process of
Dunas Lake as well as the importance of the containment plan to reduce the contamination. Finally, a
summary of the recent situation after two decades of rehabilitation is provided
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