| We regarded Yellow River as the research object in this paper, Iron and phosphorus forms and distributions and iron effected phosphorus forms and phosphorus release in the surface sediments of Yellow River mainstream were studied by improved sequential exctraction technique of iron and phosphorus in particles. Through analysised the correlativity ofΣFe and ΣP, iron forms and phosphorus forms in sediment samples,To reveal the relationships between iron and phosphorus forms in the sediments of Yellow River, Used some methods such as that based on the total amount of metal,morphology and ratio method of w(ΣFe)/w(ΣP),w-(Fe/Al-P)/w(Ca-P), Forecasted and identified that release risks of p and the potential risks of eutrophication in the sediment of Yellow River.Combined with wide range of artificial dam in the Yellow River Basin.Discussed the influence of lower TPM by artificial dam to eutrophication in middle and lower reaches of Yellow River and iron cycle, phosphorus cycle. The results showed that:(1) F6 was highest content on Various forms of iron in the sediments of Yellow River, it was a significant positive correlation with ΣFe,Instructions ΣFe content was controlled by F6; BFe contents is very low,far lower than Fe-6, But it showed significant positive correlation withΣFe. Fe-4 was the subject of BFe, BFe showed a significant positive correlation with F4 and OM, Instructions BFe was controled by Fe-4 and OM.(2) IP content was high in sediments of Yellow River, it have a significant positive correlation with ΣP, Instructed ΣP was limites by IP,Porg contents was low and far lower than IP, The reason was the lower OM contents in the sample.(3) PCa contents were higher in sediments of Yellow River, Bio-P contents was lower, Leading to a lower risk that released phosphorus in the sediments of Yellow River. In addition, in the ratio of w(Bio-P)/w(PCa)in the 21 stations of Yellow River, w(Bio-P)/w(PCa) was higher than 0.5only in Dayudu H15 section sediments of the Yellow River, w(Bio-P)/w(PCa) were lower than 0.5 in the sediments of other rivers. it was shown that release level of phosphorus was lower in sediment of Yellow River. But the strength of release phosphorus was strength in Dayudu section. It has the potential risk that occurred eutrophication.(4) Artificial dams of Yellow River Basin lead to a reduction of TPM level more than the normal number,TMP concentration has a significant reduction because of running Haibowan Yellow water conservancy project、Sanshenggong Water Project and the Sanmenxia Dam in Yellow River,Produced a negligible impact to phosphorus cycle,While has little effect on iron cycle.Iron is mainly affected the biogeochemical cycling of phosphorus by impact of the release of phosphorus, it has a certain relationship with the geology and geomorphology in Yellow River.(5) Active iron(Fe-1) and iron of steady state(Fe-6) have a great impact for the distribution of the content of ΣP in the sediments of Yellow River, and Fe-1 and Porg have a significant positive correlation, Fe-2 with Pex and PA1 have a significant negative correlation, Fe-6 and Paut, PDe have a significant positive correlation.Showed that release of phosphorus was limited by iron in most of the sediments of Yellow River.But, The release of phosphorus of H4, H5, H7, H8, H13, H16 segment in the sediments of Yellow River, There were affected by other factors such as geological and geomorphological conditions, the level of development of industrial and agricultural production and artificial dams.(6) The content of OM and ΣP in the upper reaches of the Yellow River sediment is significantly higher than the downstream.The distribution trends of ΣFe and TP in the overlying water was contrary with OM and ΣP, the upper reaches of the Yellow River was significantly lower than the downstream. In addition, The content of ΣFe and ΣP in sediments of Yellow River was close to the Taihu Lake, the Yangtze River and the Xuanwu Lake, below the severe eutrophication Haihe River and East Lake. |
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