Journal of Environmental Biology

Effect of dissolved oxygen deficiency on ²¹⁰Pb content in mussel's tissues at the Johor strait, Malaysia

N.A.B. Saili and C.A.R. Mohamed* 

Department of Earth Sciences and Environment, Faculty of Science and Technology,Universiti Kebangsaan Malaysia, Bangi, 43600, Malaysia

*Corresponding Author Email : carmohd@ukm.edu.my

Received: 14.11.2020                                                                   Revised: 17.03.2021                                                         Accepted: 26.03.2021

Abstract

Aim: To investigate the effect of dissolved oxygen deficiency on the level of ²¹⁰Pb in mussel's tissues, Perna viridis which has been reported to be highly tolerant to hypoxia.

Methodology: Mussels (Perna viridis), seawater and sediment samples were collected from nine stations along the Johor Straits during North-east monsoon (November 2017), inter-monsoon (March 2018), and South-west monsoon (August 2018).  The 210Pb contents were extracted and estimated by Gross Alpha-beta Counter.

Results: The lowest dissolved oxygen was recorded at Station 4 which decreased from 2.14 mg l^-1 to 2.10 mg l^-1 and subsequently to 1.63 mg l^-1 during first to third samplings. In sediment, ²¹⁰Pb activities increased with the increase in organic matter. Meanwhile, in mussels, the ²¹⁰Pb activities showed almost similar trend with sediment where 210Pb activities were much higher adjacent to the causeway structure, especially at the East part of Johor Strait.  The level of ²¹⁰Pb in mussel's tissue and sediment also increased with decreasing level of dissolved oxygen.      

Interpretation: A causeway structure disrupted the water quality of Johor Straits and caused almost hypoxic conditions nearby. The coverage of oxygen depletion expanded during inter-monsoon. An inverse relationship between ²¹⁰Pb activities and dissolved oxygen prove that deficiency of dissolved oxygen potentially influenced the bioaccumulation of ²¹⁰Pb in mussels to correspond to the build-up of concentration factor in their tissues which exceeded the recommended value.      

Key words: Dissolved oxygen, Hypoxic, Organic matter, ²¹⁰Pb, Perna viridis

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