第五节 海水中的亚硝酸盐

CHAPTER 3 SEAWATER CHEMISTRY Section 5 Nitrite in the Xiamen Harbour Waters

海水中的NO2-N是NH4-N氧化与NO3-N还原的中间化合物,其含量通常是三种无机氮中最低的。它与NH4-N和NO3-N一样,可直接为浮游植物同化。河口港湾水体中的NO2-N主要来自大陆径流、沿岸排废和其他氮化合物的分解、转化,浮游植物在过度摄食期间亦可直接排泄NO2-N。关于海水中NO2-N含量的分布及其调节过程已有不少报道,但一般认为其影响因素较多,规律性较差。本节报道了厦门港湾水体中NO2-N浓度的空间分布和时间变化;探讨了盐度、活性磷酸盐浓度、溶解氧饱和度、叶绿素a浓度和九龙江水的NO2-N浓度与其周日和月变化的关系,并通过多元线性回归,给出了确定的关系式。

The values of nitrite were between 0.0—4.92μmol·N/L,95%of the data were below 2.55μmol/L,the total average was 0.91μmol/L.The horizontal difference between maximun and minimun nitrite concentrations were 0.13—2.86μmol/L,averaged at 1.11μmol/L.The nitrite content at the longitudinal transect in areaⅢpresented a quite typical wedge Palter with high value on upper water layer and low value on the lower.The vertical distribution of nitrite concentration in areaⅠ,Ⅱwere basically low on the upper water column and high on the lower,while it was opposite in areaⅢ;usually it was un-even distributed for the water between 0—10m.The vertical gradients of nitrite is clearly positively correlated with its concentration.The daily variation was 0.11—3.25μmol/L with mean of 0.69μmol/L.The daily difference(Rd)of a layer for various stations presents clear complex correlationship with the average salinity(S)and nitrite concentration(C):Rd=1.440+0.478C-0.041S(n=78,R=0.708,F=37.7)For stations where the nitrite concentration are high and the salinity is low,Rd values are high and nitrite is clearly correlated with salinity,for these sations locating inner part of the estuary,nitrite is also clearly positively correlated with PO4-3-P;for stations where the nitrite is low and salinity is high,Rd is low and nitrite is not clearly correlated with salinity but it is clearly positively correlated with PO4-3-P.The monthly variation of nitrite was high in October-December and low in February-August for areaⅠ;for areasⅡandⅢ,its valley value appeared in February and August 1981,the peak in April 1981 and October-December 1980.The variables clearly correlated to NO2--N are(n=6):for areaⅠ[NO2--N]=-0.057+0.761[PO43-P](R=0.948,F=36.1)for areaⅡ[NO2-N]=8.567-0.242S-0.210[Chl-a](R=0.938,F=11.0)for areaⅢ[NO2--N]=2.915-0.098S+0.269[NO2--N](R=0.998,F=372)The concentration range,average and variation magnitude of horizontal,transect,vertical,daily and monthly values are often areaⅢ>areaⅡ>areaⅠ.Either diurnal or spacial data of nitrite show very clear positive partical correlationship with PO43-P,which is particularly observed of areaⅠwhere the fresh water influence is slight;nitrite is also quite clearly correlated with salinity.