胶州湾表层水中低分子量有机酸的分布及特征

摘要

用高效液相色谱法对2010-10在胶州湾15个站位获取的表层海水样品中低分子量有机酸(LMWOAs)进行了定性、定量分析.结果表明,高效液相色谱法能够在胶州湾表层海水中检测到3种典型的低分子量有机酸,分别为乳酸、乙酸和甲酸,这3种酸的总浓度(TOA)的变化范围为18.02～24.66 μmol·L-1,平均浓度为20.95±1.95 μmol·L-1；乳酸、乙酸和甲酸浓度变化范围分别为1.72～11.11,4.47～17.98,2.89～6.04 μmol·L-1,平均浓度分别为(3.25±2.25),(12.77±2.94),(4.90士1.27)μmol·L-1,乙酸的平均浓度显著高于甲酸和乳酸.总体而言,3种酸的分布呈现近岸高、远岸低的趋势,人类活动是胶州湾有机酸的主要来源并且对LMWOAs的分布有决定性的影响.分析了溶解有机碳(DOC)、叶绿素a(Chl-a)的浓度分布以及它们与LMWOAs之间的关系.DOC的浓度变化范围为140.25～197.50μmol·L-1,平均浓度为(161.22±17.67) μmol·L-1；Chl-a的浓度变化范围为0.70～1.45 μmol·L-1,平均浓度为(0.91±0.28) μmol·L-1.发现TOA浓度与TOA/DOC之间存在一定的相关性,TOA浓度与Chl-a浓度缺少相关性,表明生物活动对胶州湾LMWOAs的影响不明显.%Qualitative and quantitative analyses of low molecular weight organic acids (LMWOAs) in the surface water samples collected from 15 stations in the Jiaozhou Bay in October 2010 were conducted by means of high performance liquid chromatography (HPLC). The results show that three typical LMWOAs, lactate, acetate and formate, are detected in the surface water of the Jiaozhou Bay. The total concentration of the three acids (TOA) ranges from 18. 02 to 24. 66 mol L-1 , with an average of (20. 95 + 1.95) molL-1. Concentrations of lactate, acetate and formate vary between 1.72—11. 1K4. 47 —17.98 and 2.89 — 6.04 μmol ? L-1 and have the average values of (3. 25 + 2. 25), (12. 77 + 2. 94) and (4. 90 + 1. 27) μmol ? L-1 respectively. The average concentration of acetate is significantly higher than those of lactate and formate. In general, the concentrations of the three acids tend to be higher nearshore and lower offshore. The human activities are the major sources of LMWOAs and affect critically the distributions of LMWOAs in the bay. In addition, concentrations of dissolved organic carbon (DOC) and chlorophyll a (Chl-a) and their relationships with TOA were also analyzed. The results show that the concentration of DOC in the surface water of the Jiaozhou Bay ranges from 140. 25 to 197. 50 mol L-1 , with an average of (161. 22 + 17. 67) mol L-1 , and the concentration of Chl-a ranges from 0. 70 to 1. 45 mol L-1 , with an average of (0. 91 0. 28) mol L-1. The study also find that a distinct correlation occurs between the concentration of TOA and the ratio of TOA/DOC (R = 0. 554 6, n=15, P<0. 05), but between the concentrations of TOA and Chl-a no significant correlation has been found, indicating that the biological effects on LMWOAs is not remarkable in the bay.