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Palynomorphs in surface sediments of the North-Western Black Sea as indicators of environmental conditions
Quaternary International ( IF 1.9 ) Pub Date : 2020-05-01 , DOI: 10.1016/j.quaint.2020.05.014
Peta J. Mudie , Valentina V. Yanko-Hombach , Inna Mudryk

Abstract Most previous Black Sea palynology studies have used pollen-spore assemblages as proxies for climate and landscape changes, and dinocyst assemblages as proxies for surface water salinity. However, there are few data on within-region variations in these assemblages using large sets of surface samples and a full suite of palynomorphs, including terrigenous pollen + spores, freshwater algal spores, and organic remains of marine microplankton, micro- and meiobenthos. Here we fill this knowledge gap, using results from a palynological study of 43 surface samples from water depths of 71–905 mbsl on the Ukrainian Shelf and adjoining continental slope, NW Black Sea. The palynology samples were collected in conjunction with water and sediment chemistry data, grain-size, micropaleontological and meiobenthos data from the EU-FP6 project HERMES “Hotspot Ecosystems Research on the Margins of European Seas”. This dataset uniquely covers shelf and upper slope areas east and west of the Odessa-Sinop Fault Zone (OSFZ) that delimits areas of lower and higher hydrocarbon gas contents, respectively. The new data show that on the wide shelf with a shallow (ca. 80 m) oxycline, pollen assemblages differ from classical models for marine pollen transport. On the Ukrainian Shelf, pollen concentrations are extraordinarily high far offshore and the grains are often pyrite-infilled. These features apparently reflect high pollen preservation potential in low oxygen sediments, probably enhanced by cross-shelf transport of land-derived particulate organic matter. The new data have important consequences for accurate modelling of carbon burial and storage in epicontinental seas, and they provide a baseline for evaluating marine pollen concentrations expected to reflect the early Neolithic farming on the Ukrainian shelf. Furthermore, although large concentrations of dinocysts comprise more than half of the total Non-Pollen Palynomorphs (NPP), the high pollen concentrations skew the P:D index (pollen:dinocyst ratio) commonly used to evaluate changes in paleo-shoreline (proxy sea-level) positions. Despite the discharge of several large rivers to the Ukrainian Shelf, there are negligible traces of freshwater algae in the HERMES samples except at Sta. 15 where Pediastrum is abundant. Overall, palynomorphs of terrestrial origin make up about half (52%) of the acid-resistant organic-walled particles on the outer NW Black Sea Shelf and adjacent slope. The abundances of the major micro- and meiobenthic palynomorph groups show the same trends east and west of the OSFZ as the micropaleontological data reported for the HERMES samples taken at the same sites. The combined microzooplankton and zoobenthos surface assemblage data provide an important new baseline for evaluating historical and past changes in biodiversity and aquatic foodweb structure in the now polluted NW Black Sea. Comparison can also be made with foodweb reconstructions for Permian black shales.

中文翻译:

黑海西北部表层沉积物中的孢粉形态作为环境条件的指标

摘要 以前的大多数黑海孢粉学研究都使用花粉-孢子组合作为气候和景观变化的代表,使用双囊组合作为地表水盐度的代表。然而,使用大量地表样本和全套孢粉体(包括陆源花粉 + 孢子、淡水藻类孢子和海洋微型浮游生物、微型底栖动物和小型底栖动物的有机遗骸),关于这些组合的区域内变化的数据很少。在这里,我们使用来自乌克兰大陆架和毗邻的黑海西北部大陆坡上 71-905 mbsl 水深的 43 个表面样本的孢粉学研究结果填补了这一知识空白。孢粉学样本是结合水和沉积物化学数据、粒度、来自 EU-FP6 项目 HERMES“欧洲海洋边缘热点生态系统研究”的微古生物和小型底栖动物数据。该数据集独特地涵盖了敖德萨-锡诺普断裂带 (OSFZ) 以东和以西的陆架和上斜坡区域,分别界定了较低和较高烃类气体含量的区域。新数据显示,在具有浅(约 80 m)氧化层的宽阔架子上,花粉组合与海洋花粉运输的经典模型不同。在乌克兰大陆架上,离岸很远的地方花粉浓度非常高,而且谷物中通常充满了黄铁矿。这些特征显然反映了低氧沉积物中的高花粉保存潜力,可能通过陆源颗粒有机物的跨架运输增强。新数据对大陆表海中碳埋藏和储存的准确建模具有重要意义,它们为评估海洋花粉浓度提供了基线,预计将反映乌克兰大陆架上新石器时代早期的农业。此外,虽然大浓度的双孢子囊占无花粉孢粉 (NPP) 总数的一半以上,但高花粉浓度使 P:D 指数(花粉:双孢子囊比)通常用于评估古海岸线(代理海)的变化。 -级)职位。尽管有几条大河向乌克兰大陆架排放,但 HERMES 样品中的淡水藻类痕迹可忽略不计,除了 Sta。15 Pediastrum 丰富的地方。全面的,来自陆地的孢粉型约占黑海大陆架西北和相邻斜坡上耐酸有机壁颗粒的一半 (52%)。主要微型和小型底栖孢粉类群的丰度显示出与在相同地点采集的 HERMES 样本报告的微古生物学数据相同的 OSFZ 东部和西部趋势。结合微型浮游动物和底栖动物表面组合数据为评估现在被污染的黑海西北部生物多样性和水生食物网结构的历史和过去变化提供了重要的新基线。也可以与二叠纪黑色页岩的食物网重建进行比较。主要微型和小型底栖孢粉类群的丰度显示出与在相同地点采集的 HERMES 样本报告的微古生物学数据相同的 OSFZ 东部和西部趋势。结合微型浮游动物和底栖动物表面组合数据为评估现在被污染的黑海西北部生物多样性和水生食物网结构的历史和过去变化提供了重要的新基线。也可以与二叠纪黑色页岩的食物网重建进行比较。主要微型和小型底栖孢粉类群的丰度显示出与在相同地点采集的 HERMES 样本报告的微古生物学数据相同的 OSFZ 东部和西部趋势。结合微型浮游动物和底栖动物表面组合数据为评估现在被污染的黑海西北部生物多样性和水生食物网结构的历史和过去变化提供了重要的新基线。也可以与二叠纪黑色页岩的食物网重建进行比较。
更新日期:2020-05-01
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