Geochemical characteristics of the sediment elements at tidal flat and its environmental implications at Yuantuojiao Point, estuary of the north branch of the Changjiang River
Received date: 2014-11-19
Request revised date: 2015-03-04
Online published: 2015-07-12
Copyright
Yuantuojiao Point is located at the intersecting site of the north branch of the Changjiang River and Jiangsu coast. In the study area the typical silt-mud tidal flat has been the main morphological type. The geochemical elements of the tidal flat sediments are the proxies indicating the coastal environmental changes. In this study, a 218 cm drilling core was collected on the tidal flat at the Yuantuojiao Point. The grain size, 7 macroelements (Al, Fe, K,Mg, Ca, Na, Ti) and12 microelements (Mn, Ni, Sr, V, Zn, P, Ba, Be, Cr, Co, Cu, Li) of the YY core were measured. The chronology of this core was established by the method of 137Cs dating. The results indicate that the contents of most macroelements and microelements had higher values in the lower part of the core, but in the upper part the values of the contents were lower.The maximum value of most macroelements and microelements existed at a depth of 132 cm of the YY core (except Ca, Na, Ti, P and Sr), which should be studied in the future. The mean grain size of the YY core had a good relationship with most elements contents, indicating a distinct feature of "grain size control effect". The grain size and the contents of elements corrected by clay from the YY core had greater difference before and after 1956. The evidences of the longshore current direction, coast spit extension direction, hydrodynamic change of north branch of the Changjiang River indicated the Jiangsu offshore region was the sediment source of the north branch of the Changjiang River. We made an analysis of the elements enrichment coefficients of the sediments of the YY core before and after 1956 at the Yuantuojiao Point and the adjacent areas. It is indicated that the main sediments of the tidal flat at the Yuantuojiao Point derived mainly from the Changjiang River before 1956, but they were mainly from the southern part of the submarine radial sand ridges of South Yellow Sea after 1956.
Key words: tidal flat; macroelements; microelements; Yuantuojiao Point; Changjiang River
XIE Li , ZHANG Zhenke , HE Huachun , TANG Meng , REN Hang , JIANG Songliu . Geochemical characteristics of the sediment elements at tidal flat and its environmental implications at Yuantuojiao Point, estuary of the north branch of the Changjiang River[J]. GEOGRAPHICAL RESEARCH, 2015 , 34(6) : 1053 -1065 . DOI: 10.11821/dlyj201506005
Fig. 1 Geographical setting and the location of the YY core at the Yuantuojiao Point图1 圆陀角附近地理环境和YY孔位置 |
Fig. 2 137Cs profile of the YY core图2 YY孔岩芯137Cs垂直剖面 |
Fig.3 Vertical profiles of the grain size and macroelement concentration in YY core图3 YY孔岩芯沉积物粒度与常量元素含量垂向变化 |
Fig. 4 Vertical profiles of the grain size and microelement concentration in YY core图4 YY孔岩芯沉积物粒度与微量元素含量垂向变化 |
Tab. 1 The correlation analysis of the macroelements and grain size parameters in YY core表1 YY孔岩芯沉积物常量元素与粒度参数相关分析 |
| Al | Ca | Fe | K | Mg | Na | Ti | mean | clay | |
|---|---|---|---|---|---|---|---|---|---|
| Al | 1 | ||||||||
| Ca | -0.055 | 1 | |||||||
| Fe | 0.980** | -0.113 | 1 | ||||||
| K | 0.932** | -0.321 | 0.954** | 1 | |||||
| Mg | 0.920** | 0.011 | 0.943** | 0.866** | 1 | ||||
| Na | -0.676** | 0.194 | -0.712** | -0.747** | -0.661** | 1 | |||
| Ti | 0.143 | 0.580** | 0.148 | -0.081 | 0.124 | 0.058 | 1 | ||
| mean | 0.868** | -0.346 | 0.920** | 0.941** | 0.843** | -0.673** | -0.111 | 1 | |
| clay | 0.885** | -0.296 | 0.932** | 0.931** | 0.881** | -0.702** | -0.075 | 0.986** | 1 |
注:**表示在0.01水平(双侧)上显著相关。 |
Tab. 2 The correlation analysis of the microelements and grain size parameters in YY core表2 YY孔岩芯沉积物微量元素与粒度参数相关分析 |
| Ba | Be | Co | Cr | Cu | Li | Mn | Ni | P | Sr | V | Zn | mean | clay | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ba | 1 | |||||||||||||
| Be | 0.787** | 1 | ||||||||||||
| Co | 0.822** | 0.837** | 1 | |||||||||||
| Cr | 0.826** | 0.848** | 0.960** | 1 | ||||||||||
| Cu | 0.772** | 0.862** | 0.920** | 0.843** | 1 | |||||||||
| Li | 0.810** | 0.884** | 0.943** | 0.868** | 0.976** | 1 | ||||||||
| Mn | 0.849** | 0.880** | 0.978** | 0.941** | 0.941** | 0.970** | 1 | |||||||
| Ni | 0.836** | 0.851** | 0.955** | 0.878** | 0.941** | 0.963** | 0.961** | 1 | ||||||
| P | -0.020 | -0.271 | -0.030 | 0.120 | -0.364 | -0.307 | -0.095 | -0.192 | 1 | |||||
| Sr | 0.610** | 0.218 | 0.240 | 0.353 | 0.076 | 0.099 | 0.253 | 0.209 | 0.541** | 1 | ||||
| V | 0.889** | 0.886** | 0.967** | 0.967** | 0.912** | 0.940** | 0.980** | 0.934** | -0.028 | 0.344 | 1 | |||
| Zn | 0.837** | 0.901** | 0.945** | 0.885** | 0.986** | 0.988** | 0.970** | 0.962** | -0.298 | 0.167 | 0.950** | 1 | ||
| mean | 0.770** | 0.877** | 0.868** | 0.803** | 0.966** | 0.938** | 0.914** | 0.917** | -0.371 | 0.112 | 0.884** | 0.953** | 1 | |
| clay | 0.772** | 0.848** | 0.890** | 0.826** | 0.977** | 0.952** | 0.928** | 0.923** | -0.340 | 0.104 | 0.906** | 0.962** | 0.986** | 1 |
注:**表示在0.01水平(双侧)上显著相关。 |
Fig. 5 Vertical profiles before (solid lines) and after (dotted lines) the sedimentary element concentration corrected by clay in YY core图5 YY孔岩芯沉积物粘土校正前(实线)、后(虚线)元素含量垂向变化 |
Fig. 6 The elements enrichment coefficients of the sediments of the YY core before and after 1956 at the Yuantuojiao Point and the adjacent areas图6 圆陀角YY孔岩芯沉积物1956年前后与邻近区域沉积物元素富集系数 |
The authors have declared that no competing interests exist.
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