The Study On The Forms Of Inorganic Nitrogen And Its Relationship With Denitrification Rate In The Northwest Of The Yellow Sea

Alongside the social and economic development,high intensity human activity results in the increase of nitrogen flowing into estuarine and offshore area, and water eutrophication is becoming a more and more serious environmental problem faced by the world of today; in addition red tide occurred frequently causing serious threat to marine ecosystem. Therefore,the study of nitrogen behavior in biogeochemistry of marine ecosystem is becoming one of the important domains in oceanography,and the study of the modal inorganic nitrogen and its relation with denitrification rate play an important role in the research of marine azotic circulation.This research was supported by national basic developmental plan( 2006CB400602 ) ,comprehensive investigation of 908 in coastal marine (908-01-ST02) and the key fund of environment protect of Shandong province. The thesis studied nitrogen forms of the sediments in the North of Huanghai Sea and their biogeocemistry characters basing on the sequential extract process and studied the denitrification of interface of water-sediments using acetylene inhibition technique (AIT) during summer,spring and autumn in the North of Yellow Sea; besides,this research determined the number of denitrificational bacteria,and then analyzed the interrelation.The results also showed the characters of extractable inorganic nitrogen content and distribution. IEF-N, CF-N, and IMOF-N account for 92.25%,1.90%and5.84% of total extractable nitrogen in the sediments in Summer, the relevant results of Spring and Autumn are 86.62%,2.09%,11.37% and 91.12%,2.04%,6.85% respectively. IEF-N is the absolutely preponderant modal in the three seasons with its percentage over 85%, followed by IMOF-N with its percentage several times larger than CF-N, but evidently lower than IEF-N, and the undermost modal is CF-N with its percentage only around 2%. This thesis also determined the denitrification of interface of water-sediments of the three seasons in the North of Yellow Sea adopting acetylene inhibition technique (AIT). The results showed that the denitrification rate of the three seasons are among 3.2～7.5,0.26～2.65 and 1.21～4.12μmol/m2·h respectively indicating an evident seasonal variety with summer highest, followed by autumn. Furthermore, the thesis studied the number of denitrification bacteria of the relevant maritime space of three seasons using MPN demonstrating a greatly seasonal change. The corresponding number of Summer,Spring and Autumn are 1.18～6.18×106ind/g,0.72～4.50×105ind/g and 1.78～8.12×105ind/g respectively.The mutual relation among denitrification rate, the number of denitrification bacteria and extractable inorganic nitrogen indicated that there is an evident pertinence between denitrification rate and IEF- NO3- in summer and spring with the relevant coefficient 0.947(P<0.01) and 0.888(P<0.05)respectively; denitrification rate and CF- NH4+ in spring with the relevant coefficient 0.887(P<0.05); the number of denitrification bacteria and IEF- NO3- of spring with the relevant coefficient 0.893( P<0.05); in addition, denitrification rate and the number of denitrification bacteria are related in spring and autumn with the relevant coefficient 0.759 and 0.750(P<0.05)respectively. The study adds some academic datum to the azotic biogeochemistry circle of our coastal marine area.