Surficial Sediment Provenance And Sedimentary Environment In The Offshore Area Of The Northern Shandong Peninsula

In this study, multi-proxy including grain size, clay minerals and heavy metalswere analyzed on the surface sediments in the offshore area of Northern ShangdongPeninsula. We aim to discuss the modern hydrodynamic environment, sedimentsources, depositional environment and heavy metal pollution, especially focusing onsediment provenance and sedimentary environment.The distribution patterns of surface sediments in the offshore area of NorthernShangdong Peninsula were clarified. Clayey silt was most widely distributed in thestudy area, occupying over60%of the whole study area. Sandy silt mainly blanketedpartial area of the eastern offshore of Shandong Peninsula, while silty sands mainlyoccurred in the local area of the Northeastern and Southern Chengshantou.Surface sediments in the study area were divided into A, B, C and D four zones.Sediments of zone A and C were mostly observed in Class C and Ⅲ region in thePejrup figure, indicating the dominance of graded suspension composition in arelatively weak hydrodynamic environment. However, sediments of Zone B and Dmainly dropped in Class C, D and Ⅲ region in the Pejrup figure, implying that thedeposits were dominated by uniform suspension with less medium perturbation. Byusing Gao-Collins grain size trend model, the results showed that when Der≥0.2, thenet transport trend of sediments could be better reflected in the research area.By the high density sampling (8×5km sampling grid), it presented alongshoreerosion area and alongshore current deposition area in the study region. Sedimentarydynamics had a good zonation, consisting of coastal sandy belt and coastal mud belt.The coastal sandy belt, that is erosion and strong hydrodynamic area, showed strongtidal currents and waves. However, hydrodynamic got relatively weak in the mud belt,where it was controlled by the Yellow Sea coastal currents. Affected by the terrain,ocean circulation formed and resulted into finer deposit in the offshore local areas.Illite dominated in the clay minerals in the research area, but lower than in theYellow River and the Yangtze River. Smectite showed maldistribution, and its content was significantly higher than that of the Yellow River and the Yangtze River. Thecontent of Kaolinite in this region was very close to that of the Yangtze and YellowRiver. Chlorite were significantly lower than average levels of the Yellow River andthe Yangtze River. The comprehensive analysis of clay minerals indicated thatsediments in the study area were mainly transported from the Yellow River.By using methods of Muller land accumulation index, enrichment factor andpotential ecological risk index, heavy metals environmental assessment wereconducted on the surface sediments. The results suggested that heavy metals in thestudy area were possessed of the cleaning level, with low ecological hazards.