颗粒态有机物在长江口及其邻近海域的夏季分布和影响因素初析

SPATIAL VARIABILITY OF PARTICULATE ORGANIC MATTER IN THE CHANGJIANG RIVER ESTUARY AND ADJACENT REGIONS IN SUMMER

利用气相色谱法对长江口及其邻近海域的表层颗粒态木质素(p-lignin)进行测定和分析,结合粒度、有机碳(OC%)、叶绿素a(Chl a)、碳稳定同位素(δ13C)等参数研究颗粒态有机物的夏季分布,并对其分布影响因素进行了初步分析。结果表明,悬浮颗粒物粒度组成以粘土和粉砂为主,平均粒径为7.9μm;OC%的值为0.57—7.41%,Chl a的值为0.35—3.71μg/L,δ13C的值为-25.7‰—–16.6‰,在口门外水华站位出现OC%、Chl a和δ13C的最大值,表明浮游生物的现场生产是主要贡献;紫丁香基酚类(S)、香草基酚类(V)和肉桂基酚类(C)8种木质素酚单体的含量Λ8(相对于总有机碳的含量)为0.0406—1.47mg/100mg OC;紫丁香基系列与香草基系列的质量比值(S/V)的分布范围较宽,为0.5—1.6之间,均值为0.8;肉桂基含量与香草基含量比值(C/V)的分布范围为0.02—0.2之间,均值为0.09;香草基酚类的酸醛比值[(Ad/Al)v]在0.24—2.30之间。盐度、总悬浮颗粒物(TSM)浓度是控制长江口内区与邻近海域颗粒态有机物来源与分布差异的重要控制因素,颗粒态木质素在向海输送过程中还会受到矿物组分、生物降解、浮游生物现场生产等各种因素的作用,使其组成成分和性质发生改变。木质素等参数表明最大浑浊带尽管对颗粒态有机物向海输送有改造作用,但是影响区域有限。

We analyzed grain size, organic carbon content, chlorophyll a, stable carbon isotopes, and lignin phenols to investigate the distribution and factors that influence the distribution of particulate organic matter in the Changjiang River estuary and adjacent regions in summer of 2011. The result show that suspended particulate matters were composed of clay and silt in average grain size of 7.9μm; OC%: 0.57%—7.41%; Chl a 0.35—3.71μg/L; and δ13C –25.7‰ to –16.6‰. The maximum values of OC%, Chl a and δ13C were detected at algae bloom stations, indicating dominated contribution from phytoplankton. The sum of syringyl(S), vanillyl(V), and cinnamyl(C) phenols that normalized to organic carbon(Λ8) varied from 0.0406—1.47mg/100 mg OC; the S/V ratio was 0.5—1.6(mean at 0.8) and C/V at 0.02—0.2(mean at 0.09);(Ad/Al)v value(acid/aldehyde ratio of vanillyl phenol) was 0.24—2.30. Relationship among salinity, total suspended matter(TSM), and the ratio of Λ8 to Chl a*(normalized with particulate organic carbon or POC) suggested that the structural of organic matter in the study region was controlled by salinity and TSM. Mineral composition, microbial degradation, and in situ production were major factors affecting constituent of particulate lignin during transportation from Changjiang River into the sea. Lignin indexes in combination with POC/Chl a ratio indicate that although the TMZ could alter POC during the transportation, the area of the play is limited within the TMZ only.