“我们的海洋”行动计划确定4大关键领域

正2014年6月17日,"我们的海洋"大会宣布了新的合作关系和倡议,最终形成"我们的海洋"行动计划(Our Ocean Action Plan)。主要涉及可持续的渔业、海洋污染、海洋酸化和海洋保护等内容。(1)可持续的渔业。①到2020年彻底结束海洋渔业的过度捕捞:基于有效的科学理论,设定渔业规则;发展公平合理和透明的规程,以分配渔业权利;利用各种可获取的技术来强化渔业执法,对违规者进行惩罚;到2020年,消除渔业补贴,这些补贴促使渔业船只的生产能力过剩;要求渔业船只采用相关技术减少其     

PNAS:生命起源于深海热液假说存疑

正人类面临的一个最大的谜团是,生命是如何在地球上起源的。科学家大致确定了生命起源的时间(约38亿年前),但是在生命如何起源的问题上仍然存在很大的争议。近20年有一个可能性逐渐被人们接受——简单的代谢反应出现在古海底热泉附近,这种代谢是非生命世界向生命世界的一个跳跃。2014年4月15日,美国科学院院刊(PNAS)上发表了一篇题为《洋中脊热液流体中的甲硫醇的起源》(The origin of methanethiol in midocean ridge hydrothermal fluids)的文章,介绍了由伍兹霍尔海洋研究所     

基于文献计量的国际虚拟水研究发展态势分析

为全面了解国际虚拟水研究的整体状况和研究热点,基于SCIE和SSCI数据库,采用文献计量分析方法,对1990—2016年国际虚拟水研究相关文献进行统计分析。分析结果显示,美国、荷兰、瑞士等国的研究实力较强,荷兰特温特大学等机构在全球虚拟水研究中处于核心引领地位。全球虚拟水研究的国际合作呈现一定地缘合作特点。中国虚拟水研究已经初具规模,但研究成果的影响力与国际最高水平仍有差距,其质量和综合影响力仍有待提高。     

Coastal seas as a context for science teaching: a lesson from Chesapeake Bay

Lessons that employ authentic environmental data can enhance the ability of students to understand fundamental science concepts. This differs from traditional "environmental education" in that school curricula need not set aside time for educators to teach only environmental topics. Rather, the "environment" is used to advance student learning in science and technology. The success of this approach depends on programs that encourage scientists to communicate more effectively with teachers at all education levels. The expanding diversity of research and monitoring activities on the world's marine waters constitutes an outstanding potential education resource. Many of these projects involve remote sensing with sophisticated instrumentation and employ Internet technology to compile measurements, interpret data using graphs and satellite imagery, and share the results among scientific colleagues and the general public alike. Unfortunately, these resources, which constitute a much shortened path between research findings and textbook presentation, are seldom interpreted for use by K-12 educators. We have developed an example that uses the Chesapeake Bay as a paradigm to demonstrate how such interpretation can assist educators in teaching important principles in physical oceanography and marine ecology. We present this example using PowerPoint to conduct a virtual tour of selected Internet sources. Our example begins with the conceptual "salt wedge" circulation model of Chesapeake Bay as a partially mixed estuary. Teachers have the opportunity to explore this model using salinity, temperature, and dissolved oxygen data taken from a research vessel platform during summer professional development programs. This source of authentic data, originally obtained by teachers themselves, clearly demonstrates the presence of a picnocline and deep-water anoxia. Our lesson plan proceeds to interpret these data using additional Internet-based resources at increasing scales of time and space. The "salt wedge," picnocline, and anoxia are examined using graphics derived from data taken by researchers using "ScanFish," a towed instrument that samples temperature, salinity, and dissolved oxygen at a resolution of only a few meters vertically and horizontally. The seasonal dynamics of these parameters at a given location are interpreted using biweekly monitoring data obtained as part of the state-federal Chesapeake Bay Program. The influence of annual variations in freshwater input is examined using stream flow data from US. Geological Survey gauging stations. Satellite remote sensing images from the TOPEX/Poseidon project are used to show how El Ni?o and La Ni?a events in the mid-Pacific affect the Chesapeake Bay system via rainfall on its watershed. Finally, the life cycle of the blue crab (Callinectes sapidus) is presented to show how an estuarine organism has adapted to this truly unique and dynamic coastal environment.     

Characterization and origin of dissolved organic carbon in Yegua ground water in Brazos County, Texas

Dissolved organic carbon (DOC) concentrations in five shallow (< 20 m) and three deeper wells (27 to 30 m) in the Eocene Yegua Formation (Brazos County in east-central Texas) ranged from 92 to 500 microns. Characterization of high, intermediate, and low molecular weight DOC fractions (HMW > 3000 amu, IMW 1000 to 3000 amu, and LMW 500 to 1000 amu) and combined neutral sugar analyses provide information on organic matter sources in the Yegua aquifers. Combined neutral sugars ranged in concentration from 0.6 to 2.7 mumol/L and comprised 0.8% to 6.7% of DOC in ground water. Glucose was the most abundant neutral sugar, followed by xylose and galactose, arabinose, mannose, rhamnose, and fucose. These combined neutral sugars were more diagenetically altered in shallow, oxic ground water as indicated by high mole % fucose + rhamnose and low neutral sugar yield. The precursors for neutral sugars are most probably angiosperm leaves, which show a similar distribution pattern of neutral sugars. Ground water DOC was depleted in 13C relative to soil-zone organic matter (OM) (-16@1000 to -19@1000). The delta 13C values of bulk DOC and HMW DOC ranged from -24@1000 to -32@1000, whereas LMW and IMW DOC ranged from -32@1000 to -34@1000 and -16@1000 to -28@1000, respectively. This variability in delta 13C values is probably related to microbial processes and selective preservation of OM. Carbon isotope analyses in bulk and different molecular weight DOC fractions imply a predominantly C3 OM source and a low contribution of soil-zone OM to DOC.     

Degradates provide insight to spatial and temporal trends of herbicides in ground water

Since 1995, a network of municipal wells in Iowa, representing all major aquifer types (alluvial, bedrock/karst region, glacial drift, bedrock/nonkarst region), has been repeatedly sampled for a broad suite of herbicide compounds yielding one of the most comprehensive statewide databases of such compounds currently available in the United States. This dataset is ideal for documenting the insight that herbicide degradates provide to the spatial and temporal distribution of herbicides in ground water. During 2001, 86 municipal wells in Iowa were sampled and analyzed for 21 herbicide parent compounds and 24 herbicide degradates. The frequency of detection increased from 17% when only herbicide parent compounds were considered to 53% when both herbicide parents and degradates were considered. Thus, the transport of herbicide compounds to ground water is substantially underestimated when herbicide degradates are not considered. A significant difference in the results among the major aquifer types was apparent only when both herbicide parent compounds and their degradates were considered. In addition, including herbicide degradates greatly improved the statistical relation to the age of the water being sampled. When herbicide parent compounds are considered, only 40% of the wells lacking a herbicide detection could be explained by the age of the water predating herbicide use. However, when herbicide degradates were also considered, 80% of the ground water samples lacking a detection could be explained by the age of the water predating herbicide use. Finally, a temporal pattern in alachlor concentrations in ground water could only be identified when alachlor degradates were considered.     

Mercury levels in coral reefs along the Caribbean coast of Central America

Sediment and coral skeleton samples from 23 coral reefs along the Caribbean coast of Costa Rica and Panama (1497 km) were evaluated for total mercury (Hg). High levels of pollution were found in the entire region with averages of 18.9 and 71.3 ppb in coral skeletons and sediments respectively. Significantly higher contamination was found in Panamanian corals (21.4 ppb) while compared to Costa Rican reef sediments (85.9 ppb). Hg from several processes and non-point sources (e.g., erosion, runoff, flooding, mining, overuse of agrochemicals, industrial waste, ports, and refineries) may have affected the entire region. The widespread observed distribution suggests that Hg is being carried along long distances within the region due to its high concentrations found in “pristine” reefs. Forest burning and colonial mining residues may be considered as possible contamination factors.