Adsorption of Metals by Chitosan Beads in Sugarcane Cultivation Streams: Implications for Chironomus sancticaroli Insect Larvae (Diptera: Chironomidae)

Streams located in areas of sugarcane cultivation receive elevated concentrations of metal ions from soils of adjacent areas. This process may cause impacts on streams located in the adjacent areas. The contamination of stream sediments can lead to bioaccumulation of such metal by aquatic organisms, such as benthic invertebrates. Chitosan beads, a biopolymer that demonstrates a high affinity for metal, are simple to prepare under the laboratory, have a low overall cost, and can be used for removing metals from aquatic sediments. This work studied the use of Chitosan beads in metal adsorption from sediments of streams located in areas of sugarcane cultivation and evaluated the effects on the survival of Chironomus sancticaroli insect larvae. Acute bioassays were performed in two scenarios, in the presence and in the absence of chitosan beads. The bioassay consisted of the exposure of 10 IV instar of Chironomus sancticaroli larvae, for 96 h in five stream sediments. The results showed that chitosan beads (containing only 5.5% of chitosan) adsorbed metals in the order of Mg > Zn > Mn > Cd. The statistical results demonstrated that the addition of chitosan to the bioassays allowed a high larvae survival. The outcomes showed evidence of the viability of chitosan in remediating the metal impacts and showed a positive influence on aquatic biota.

Automated summary

Streams in sugarcane cultivation areas can be contaminated by metal ions from adjacent soils, leading to pollution of stream sediments and bioaccumulation of metal by aquatic organisms. This study investigated the use of chitosan beads to remove metals from sediments and evaluated its impact on insect larvae survival. The results demonstrated the effectiveness of chitosan beads in metal adsorption and their positive influence on larvae survival.