A Study of Sedimentary Environment in the Estuary of Nakdong River : sedimentation Processes and Heavy Metal Distributions

낙동강(洛東江) 하구역(河口域) 퇴적환경연구(堆積環境硏究) : 퇴적작용(堆積作用) 및 중금속(重金屬) 분포(分布)

The sedimentation processes and heavy metal distributions at the Nakdong estuary were investigated during October 1987 and September 1988. The depositional sedimentary environment of the studied area was estuarine environments and was divided into three provinces depending on its textural parameters such as barrier, tidal falt, and water passes. The relationship between the textural parameters showed that the barrier was under strong wave action, that the tidal flat was under relatively weak wind-driven currents, and that the water passes were under strong and continuous tidal currents. Each environments was resulted from different transport mechanism. the sand barrier sediments were transported by all three populations including suspension, saltation, and bed load, and water pass-deposited sediments were by the bad load with some suspension population. In water mass over the studied area, the concentrations of heavy metals including Cu, Cd, $Cr^{+6}$, Pb and Zn were recorded to be 27.8, 6.7, 20.4, 16.3, and 37.3 ppb in their highest concentrations, respectively. and those in sediments were 20.0, 1.65, 25.4, 15.4, and 132.0 ppm, respectively. The total up take factored of Cu, Cd, $Cr^{+6}$, Pb, and Zn by V. Muller (corbicula fluminea) were 1600, 310, 310, 490 and 7900, respectively.

낙동강 하구역에서의 중금속 분포와 퇴적작용에 대한 연구를 1987년 10월부터 1988년 9월에 걸쳐 수행하였다. 연구지역의 퇴적환경은 하구환경이며 입도분석 특성에 따라 모래섬, 수로 및 조간대 지역으로 분류된다. 모래섬의 퇴적물은 뜬짐, 틤짐, 굴 르기 상태로 운반되었으며, 조간대는 주로 뜬점과 틤틔짐으로 이동되었다. 수로의 퇴적 물은 거의 굴르기와 약간의 뜬짐 상태로 운반되었다. 모래섬은 강한 파도의 영향을 받 으며, 그 후방에 놓인 조간대는 약한 조류의 영향을 받는다. 수중에서 Cu, Cd, $Cr^{6+}$, Pb, Zn의 농도는 각각 최고의 27.9, 6.7, 20.4, 16.3, 37.3 ppb를 기록하였으며, 퇴적물에서는 20.0, 1.65, 25.4, 15.4 132.9 ppm을 나타내었다. 이들 중금속의 재첩 (V. Muller)에 의한 총섭취인자는 각각 1600, 310, 310, 490, 7900g이었다.