Distribution, Enrichment and Transport of Trace Metals in Sediments from the Dagu River Estuary in the Jiaozhou Bay, Qingdao, China

Jinqing Liu,Xiaoying Chen,Ke Cao,Ping Yin

doi:10.3390/min9090545

Abstract

26 river bank sediments and 15 estuary seafloor sediments were sampled from the Dagu River and the estuary of Northwestern Jiaozhou Bay to determine contaminations of heavy metals and metalloids (Cu, Pb, Zn, Cr, Cd, Hg and As). The trace metal contents in sediment from the estuary area were much higher than those of the river. Correlation analysis showed that except for Pb, the metals were mainly controlled by the grain size, and enriched by adsorption of aluminosilicate minerals, Fe/Mn oxides and organic matter in river and estuary sediments. In addition to Cu in some stations, the metals met the requirements of the marine organism and humans for the quality of the marine environment. The concentrations of Cu, Pb, Cr, Hg and As were between the threshold effect level (TEL) and probable effect level (PEL), indicating those metals might have occasional adverse effects. Results of Enrichment Factor values revealed that the entire study area was enriched in Pb and Hg, at moderate environmental risk, but the estuary was more significant. Pb and Hg contaminations in this area were mainly from coal combustion and automobile emissions. River runoff and atmospheric deposition dominated the metals distribution and enrichment in the study area. Contaminants in sediments entering the estuary were further transported to the south and east under the river runoff and reciprocating current in the Jiaozhou Bay.

Highlights

The coastal zone is the region most closely related to human survival and development in the ocean and a key area for studying global change, which plays an increasingly important role in modern society [1,2,3]
The entire Paleozoic strata and some Mesozoic strata are missing in the area, but the volcanic strata of the Cretaceous Qingshan Formation are well developed and widely exposed
The trend vectors were defined based on the two specific trends proposed by McLaren and Bowles (1985), which dominates along the transport path

Summary

Introduction

The coastal zone is the region most closely related to human survival and development in the ocean and a key area for studying global change, which plays an increasingly important role in modern society [1,2,3]. Urban expansion, economic development, the contradiction between the population and environment has become increasingly prominent and many coastal areas in China face serious environmental risks [4,5,6,7]. Rivers play an important role in the development of the regional economy. Coupled with runoff and sediment load that has drastically reduced, the dilution and absorptive capacity of the river has correspondingly dropped, and environmental risks are becoming increasingly severe. Background [46] (mg/kg) (mg/kg) NorthNorth China CuCu AsAs

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Discussion

Conclusion