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981.
Washed-up chondrichthyan egg cases were collected along three different sandy beaches around Plettenberg Bay, South Africa, between April 2016 and March 2017. GPS location was recorded upon collection, and, after being soaked in fresh water for 12 hours, egg cases were identified to species level. Additionally, boreholes, damage, biofouling and state of the hatchling slit were recorded. The hatching success of each egg case was inferred from these factors. Over the year, 6 996 egg cases of nine species were collected. Egg cases of the tiger catshark Halaelurus natalensis had the highest hatching rate at 70%. Egg cases of the leopard catshark Poroderma pantherinum had the highest predation rate at 57%. Season had no significant effect either on overall egg-case counts or on per-species counts. Location, however, significantly affected the overall egg-case counts, as well as per-species counts, with the exceptions of H. natalensis and the St Joseph Callorhinchus capensis. The results of this study provide insight into chondrichthyan species occurrence and spatial variation along a section of the Garden Route in the Western Cape Province and can act as a baseline for future research. 相似文献
982.
长期以来,中国海倒颚蟹属仅记录一种,即渤、黄、东海底栖动物常见种异足倒颚蟹AsthenognathusinaequipesStimpson,1858。作者对中国科学院海洋生物标本馆收藏的采自中国海的全部倒颚蟹属标本进行系统研究后共发现除该种外还有以下2种,为中国海的新记录:宽身倒颚蟹AsthenognathusgallardoiSer埁neandSoh,1976和六角倒颚蟹AsthenognathushexagonumRath-bun,1909,均采自南海北部。异足倒颚蟹为中国北方和东部海域常见种,但未见于南海。六角倒颚蟹与异足倒颚蟹形态上较相似。两者差异在于六角倒颚蟹头胸甲六角形,后缘约与额-眼眶缘等宽,背面有2对凹陷,后侧缘有2条颗粒脊,而异足倒颚蟹头胸甲后缘约为额-眼眶缘宽的1.5倍,背面仅有浅横沟。宽身倒颚蟹与其他两种形态差异较大,头胸甲宽约为长的1.9倍。 相似文献
983.
984.
985.
Shu Yang Mingli Yuan Qian Yang Jiansheng Huang Mengran Sun Jun Sun Keming Qu Yao Sun 《第四纪科学杂志》2019,34(4-5):333-341
A high‐resolution study of coccolithophores in a sediment core from the East China Sea (ECS) region of the Northwest Pacific revealed that fluctuations in coccolithophore assemblages responded well to the Pacific Decadal Oscillation (PDO) during 1901–2013. Emiliania huxleyi and Gephyrocapsa oceanica were the most dominant species, accounting for more than 97% of all the ten detected species. The variation of the two dominant species showed a significant positive correlation, and they both increased during peak values of the PDO. Decreased stratification and increased nutrient supplementation from the bottom water induced by lower sea surface temperatures in the ECS, which were associated with high PDO values, were responsible for the dominant coccolithophore increase. Similarly, the increase of Calcidiscus leptoporus also corresponded to low‐temperature and high‐nutrient conditions associated with the cold phase in the ECS (positive phase of the PDO). The responses of decadal C. leptoporus variations to changes in cold and warm phases of the PDO in the Northwest and Northeast Pacific indicate that C. leptoporus preserved in sediment cores represents a potential indicator for reconstructing phase changes of the PDO during ancient times. 相似文献
986.
Caroline Marie Clémence Tramier Pierre Genthon Quentin Réginald Camille Paul Delvienne Nicolas Luc Sauvan Jean-Jérôme Olivier Cassan Etienne Ebrard Pascal Sébastien Dumas Yann Queffélean 《水文研究》2021,35(3):e14071
In New Caledonia wildfires and invasive mammals (deer and wild pigs) constitute the major agents of land surface degradation. Our study reveals the linkage between land cover and water balance on the northeast coast of New Caledonia (2400 mm annual rainfall) located on a micaschist basement. The hydrological regime of characteristic and representative land surfaces is assessed using a 1-year record from three 100 m2 plots each, located in a forest area degraded by an invasive fauna, in a woody savannah which is regularly burned, and in a healthy forest area. The three plots present highly contrasting hydrological regimes, with annual and maximum runoff/rain ratios during a rain event of, respectively, 0.82, 0.16, 0.03, and 2.7, 0.7, 0.2, for the degraded forest, the savannah and the healthy forest. Such results suggest that subsurface flow originating from the contributing area above the degraded forest plot should exfiltrate inside the plot. A conceptual model for the degraded forest plot shows that water exfiltrating inside the plot represents 61% of the observed runoff. In savannahs, water should mainly be transferred downstream by subsurface flow within a thick organic soil layer limited by an impervious clay layer at a 20–30 cm depth. Savannahs are generally located above forests and generate the transfer of rainwater to downslope forests. Exfiltration into the forests can be the result of this transfer and depends on the thickness and permeability of the forest topsoils and on topographic gradients. Water exfiltration in forest areas highly degraded by pigs and deer enhances erosion and increases further degradation. It probably also limits percolation in the areas located downstream by increasing the amount of superficial runoff concentrated in gullies. 相似文献
987.
“双碳目标”已成为我国能源发展基本国策。如何开展这一大背景下的石油地质研究及如何推动能源多元化发展,是石油科技工作者面前的现实问题。本文对2000—2020年我国二氧化碳排放、油气能源消费、油气储量、产量等进行分析研究后认为,在“碳达峰”与“碳中和”应对全球气候变化的大背景之下,21世纪内石油和天然气仍将担任能源家族中的重要角色。我国石油工业要立足于理论和实践的自主创新,实现“万米级的超深层常规油气革命和纳米级超致密储层的非常规页岩油气革命”,实现超常规发展和低碳绿色转型发展。油田注水开发是我国提高采收率的核心技术,今后应大力推广注二氧化碳驱油技术,以达到增油与减排的双重目的,创新二氧化碳捕集与埋存技术以发展石油工业的减碳产业。21世纪为能源发展的多元化时代,水电、风能和太阳能等3类可再生能源开发利用是实现双碳目标的基本保障,地热能、生物质能和海洋能是重要推手;22世纪人类将建成一个由可再生能源和新能源保障的经济社会,氢能源将是未来最具发展潜力的新能源。 相似文献
988.
野外调查是大地构造研究的重要基础。古地理及与之相关的沉积岩石学、古生物地层学、构造地质学等在大地构造研究中一直发挥着非常重要的作用,这在著名学者葛利普、黄汲清、王鸿祯等的著作中均有充分的体现。然而,自20世纪90年代以来,在以SCI为导向的评价体系指挥下,这些比较费时、费力的工作往往受到忽视。粉末化、简单化、模式化,新八股式的所谓研究,大行其道,成为一种时尚,形成一股十分有害的逆流。为扭转这种局面,科技界领导必须转变思想,改变政策,创造良好的科研环境,使中国的学术研究走上健康发展的道路。 相似文献
989.
本文对2012年度全球发现并经国际矿物学协会(IMA)新矿物与矿物分类命名专业委员会(CNMNC)批准的90个新矿物种资料进行了系统梳理,从矿物名称、晶体化学式、晶系和空间群、晶胞参数、主要粉晶衍射数据、物理性质、光学性质、产地与产状、与其他矿物种的关系、矿物名称来源、化学反应和光谱学特征等方面归纳总结了这些新矿物的重要矿物学特征,并按照中国新矿物及矿物命名委员会颁布的《矿物种汉名审订条例》,对90个新矿物种的中文名称进行了审订。通过分批次公布国际新矿物工作的新进展和新成果,并逐步完善和规范矿物种中文译名体系,可以为我国新矿物的发现和研究提供有科学价值的参考和借鉴,并不断推进矿物种中文译名的规范化与标准化进程。 相似文献
990.
The Tibetan Plateau is an important area for studying global climate change, but the answers to many scientific problems remain unknown. Here, we present new information from the lacustrine sedimentary record in the western Tibetan Plateau, related to the third most-recent glaciations. Continuous sediment data, including sporopollen, particle size, total organic carbon, mass susceptibility, CaCO3, CaSO4, BaSO4 contents and chronological data, were reconstructed and revealed that climate and environmental conditions obviously and distinctly changed between 600 and 700 thousand years ago. In comparison, the data obtained from the Guliya ice core in this area also corresponds to the global glacial climatic characteristics recorded in basin sediments in the eastern and southeastern regions of the plateau and to the information obtained from ice cores in the Antarctic and Arctic regions. In this study, we conclude that the main reason for the glaciations and new tectonic movement must be a geomagnetic polarity reversal 774 thousand years ago (from Matuyama to Brunhes). Indeed, the results of this study suggest that the described reversal event might have influenced the current global climate pattern and will continue to impact climatic changes in the future. 相似文献