Effect of pH on transport and transformation of Cu-sediment complexes in mangrove systems. (August 2018) - Jayachandran, Saranya
Abstract: Impact of pH variation of overlying water column on transport and transformation of Cu-sediment complexes in the bottom mangrove sediments was investigated by using different metal extraction studies. The total Cu concentration in the studied sediments varied from ~64 ± 1 to 78 ± 2 mg·kg −1 . The sequential extraction study showed that a major part of the sedimentary Cu (85–90% of the total sedimentary Cu) was present within the structure of the sediments with minimum mobility and bioavailability. The redistribution of non-residual Cu among the different binding phases of the sediments was observed at different pH. It was found that Cu shifted from the different non-residual binding phases to the organic binding phase of the sediments at higher pH. Partial leaching of sedimentary Cu-SOM complexes (with increasing stability as determined by kinetic extraction study) was observed at higher pH. This study infers that increase in pH of overlying water column may release Cu-SOM complexes and increase the mobility of Cu-complexes in mangrove systems. Highlights: Distribution of Cu in different binding phases of sediments changes with changing pH of the surrounding environment. Association of Cu organic matter increases at higher pH with sedimentary increases at higher pH. Cu-SOM complexes may disaggregate and increase mobility at higher pH. Increasing pH decreases lability of Cu complexes and increase mobility of Cu-complexes in sediments. Concentration Cu in residual phases remains unchanged under varying pH.