Trace metal concentrations in salt marsh sediments from Bakkhali River estuary, Cox’s Bazar, Bangladesh

Abstract

Trace metal concentrations (Cu, Zn, Cadmium (Cd), and Pb) in salt marsh sediments of the Bakkhali River estuary, Cox’s Bazar, were investigated. Sediment samples from four different sites were analyzed for the selected trace metals by atomic absorption spectrophotometer. The mean value of trace metals ranged 27,18–41.76 μg/g for Cu, 93.51–106.38 μg/g for Zn, 0.16–0.36 μg/g for Cd, and 21.28–32.08 μg/g for Pb in this salt marsh bed. In the correlation matrix, Cu positively correlated with clay (r = 0.968, p < 0.05) and silt (r = 0.995, p < 0.01), and Pb positively correlated with clay (r = 0.961, p < 0.05), silt (r = 0.998, p < 0.01), and Cu (r = 0.999, p < 0.01). Negative correlations were also found between Cu and sand (r = −0.999, p < 0.01) and Pb and sand (r = −0,999, p < 0.01). The mean concentrations of trace metals from most of the stations were found slightly higher than the recommended value of unpolluted soil. Our findings indicate that the salt marsh bed in the Bakkhali River estuary accumulates trace metals. The results of this study could help to control coastal pollution and improve coastal management in this area in future.

Bakkhali upės žiotyse, Bangladeše, esančios druskingos pelkės keturiose vietose buvo paimti nuosėdų mėginiai, kuriuose mikroelementų Cu, Zn, Cd ir Pb koncentracija ištirta atominės absorbcijos spektrofotometru. Cu vidutinė vertė buvo 27,18–41,76 μg/g, Zn – 93,51–106,38 μg/g, Cd – 0,16–0,36 μg/g, Pb ir – 21,28–32,08 μg/g. Teigiama koreliacija nustatyta tarp Cu ir molio (r = 0,968, p < 0,05) bei dumblo (r = 0,995, p < 0,01) dirvožemyje, o taip pat tarp (ir Pb) molio (r = 0,961, p < 0,05), dumblo (r = 0,998, p < 0,01) dirvožemyje bei Cu (r = 0,999, p < 0,01) koncentracijos. Neigiamos koreliacijos nustatytos tarp Cu ir smėlio (r = −0,999, p < 0,01) bei tarp Pb ir smėlio (r = −0,999, p < 0,01). Daugumoje tyrimo vietų vidutinė mikroelementų koncentracija nežymiai viršijo neužterštam dirvožemiui rekomenduojamą koncentraciją. Gauti duomenys rodo, kad Bakkhali upės žiotyse esančios druskingos pelkės dugne kaupiasi mikroelementai. Tyrimo rezultatai gali būti panaudoti kontroliuojant pakrantės taršą ir gerinant pakrantės valdymo priemones ateityje.

Keywords:

• trace metals
• salt marsh sediments
• Bakkhali River estuary
• Cox’s Bazar
• Bangladesh

Acknowledgments

The authors want to express their gratitude to the Director of the Institute of Marine Sciences and Fisheries of University of Chittagong for providing necessary facilities pertaining to this work. The authors are grateful to anonymous reviewers for their insightful comments which enabled improvement of the manuscript.