The C37 alkenone record of sea water of time series station DYNAPROC

The concentrations of suspended particulate pigments, C37-C38 alkenones, total organic carbon and nitrogen in the Ligurian Sea (northwestern Mediterranean) have been studied at 5 and 30 m depth during well defined thermocline conditions. An accurate description of the short term changes of these compounds has been achieved by means of four 36-h sampling cycles each encompassing consecutive filtration periods of 4 h. During sampling the thermocline changes were followed closely by simultaneous measurements of water column temperature, salinity and other physical parameters. The analysis of the collected samples indicates that the Haptophyte pigments and alkenones are essentially synthesized at the levels of highest primary production and therefore the C37 alkenone record reflects the seawater temperature at this depth level. The study also shows that part of these alkenones are distributed throughout the water column in association to the suspended particles. This process results in C37 alkenone distributions that, due to their high resistance to chemical and microbial degradation, record the temperature of the highest primary productivity layers even at shallow (e.g., 5 m depth) or deep (e.g., 1100 m depth) waters.

本数据集针对地中海西北部利古里亚海（Ligurian Sea）在明确温跃层（thermocline）条件下，于5米和30米水深的水体中，对悬浮颗粒色素、C37-C38长链烯酮（alkenones）、总有机碳与总氮的浓度展开研究。研究通过4组36小时的采样周期完成，每组周期包含连续4小时的过滤采样时段，由此精准刻画了上述化合物的短期变化特征。采样期间，同步测定水柱温度、盐度及其他物理参数，以实时追踪温跃层的动态变化。对采集样品的分析结果表明，定鞭金藻（Haptophyte）色素与长链烯酮主要在初级生产力最高的水层合成，因此C37长链烯酮的记录可反映该水层的海水温度。本研究同时发现，部分长链烯酮会伴随悬浮颗粒在整个水柱中分布；由于这类化合物对化学与微生物降解具有极高耐受性，即便在浅层（如5米水深）或深层（如1100米水深）水体中，C37长链烯酮的分布仍可记录初级生产力最高水层的温度。