| Coastal region is the most active coupling zone interacted by ocean interaction, atmosphere interaction, biological interaction, geologic course and human activities, thus the pollutants’behavior in this region has its unique characteristics as it is affected by the complex environment. Estuary sediments are not only the sink of OCPs and phosphorus, but also the potential "secondary pollution source" by re-suspension action or food chain enrichment. Therefore it is important to develop researches on the characteristics and behavior of OCPs and phosphorus in the sediments of coastal intertidal flat region. Along the coastline of Jiangsu province, there is the largest muddy/silty coastal wetland in China, with a total area of 45.6 hm2, and extends 954 km from north to south. Sixteen surface sediment samples were collected and analyzed typically to evaluate the residues of Organochlorine Pesticides (OCPs) and phosphorus from tidal flat of Jiangsu Province.The results indicated that the concentrations of OCPs varied widely with a high variation coefficient from different sampling sites. Total OCPs residues concentrations ranged from 0.96 to 12.14 ng g-1, with a mean of 3.57 ng g-1, concentrations of the total HCHs and DDTs were n.d.-0.67 ng g’1 and 0.23-4.85 ng g-1, with means of 0.24 and 1.84 ng g-1, respectively. As to other OCPs, mean values of Endosulfan Ⅱ (0.40 ng g-1) and Heptachlor (0.23 ng g"1) were the highest two, while the lowest one was trans-Nonachlo (0.01 ng g-1). DDTs were the most predominant compounds, accounting for 52% of the total OCPs, approximately. The highest concentration of ∑OCPs was found at S1 (12.14 ng g-1), and followed by S11 (9.24 ng g-1), S16 (6.00 ng g-1). The spatial distribution of total CPs wre in this sequence:Nantong City coastal zone> North of Lianyungang City coastal zone> Yancheng City coastal zone. The dominance of β-HCH indicated a historical pollution of HCHs. According to the ratios of (DDD+DDE)/DDT and o,p’-DDT/p,p’-DDT, there was no new input of DDTs in most sites and the main sources were historical usage of technical DDTs.The concentrations of HCHs and DDTs in this study were compared to those of other estuarine/coastal regions. Generally, levels of HCHs in the surface sediment of intertidal flat from coastal zone of Jiangsu Province were relatively lower than those in other regions, while the concentrations of DDTs in this work were comparable to those presented in Pearl River Estuary, Yellow River Delta, Bohai Sea, Hangzhou Bay and East China Sea, but lower than the levels of Yangtze Estuary significantly.100% of the p,p’-DDE were below ERL, and as to p,p’-DDD, p,p’-DDT and DTs, a few of sites had slightly higher levels than ERL, with p,p’-DD at SI, p,p’-DDT at S13,∑DTs at S1, S11 and S13, indicating that adverse biological effects would occur at these three sites occasionally. For Dieldrin and Endrin, although not exceed ERM,44% and 56% of total sites in the study area were higher than ERL, suggesting that the exposure of Dieldrin and Endrin may cause ecological risk.Concentrations of the total phosphorus ranged from 497.1-1036.2μg·g-1, with a mean of 755.7 μg·g-1. Compared with other estuarine/coastal regions, levels of total phosphorus in this study were raletively higher.The highest concentration of total phosphorus was found at S14 (1036.2 μg·g-1), and followed by S10 (993.1μg·g-1), and then S9 (936.4μg·g-1), S1 (892.1μg·g-1). The spatial distribution of total phosphorus wre in this sequence:Nantong City castal zone> North of Lianyungang City castal zone>Yancheng City castal zone.The concentrations of inorganic phosphorus and organic phosphorus were ranged from 449.5-842.0μg·g-1 and from 47.6-326.6 μg·g-1, accounting for 62.5%-90.4% and 37.5%-9.6% of the TP, respectively. Inorganic phosphorus was the most predominant compounds of TP.There is a good linear relationship TOC content and NaOH-P, indicating that the organic matters in sediments may have affect on the NaOH-P content and distribution.TP has a significant linear correlation with OP, IP and HCl-P. And the linear correlation between IP and TP was the highest, indicating that IP has an importanf effect on the distribution and concentration of the TP. IP and HCl-P has a significant positive correlation, indicating that the HCl-P is the most important component of IP. OP has a positive correlation with NaOH-P and Eh, while the related linearity between OP and pH is significantly negative, indicating that pH has a critical influence on the adsorption and release of OP.NaOH-P and HCl-P were negatively correlated. The risk assement of TP showed pollution of phosphorus in this study were at a raletively lower level. |
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