Novel solvent systems for in situ extraterrestrial sample analysis

The life marker chip (LMC) is being designed to test for the chemical signature of life in the soil and rocks of Mars. It will use an antibody array as part of its detection and characterisation system and aims to detect both polar and non-polar molecules at the sub-ppm to tens of ppb level. It is necessary to use a solvent to transfer organic compounds from the Martian samples to the LMC itself, but organic solvents such as dichloromethane or hexane, commonly used to dissolve non-polar molecules, are incompatible with the LMC antibodies. Hence, an aqueous-based solvent capable of dissolving the biomarkers that might exist in the soil or rocks of Mars is required. Solvent extractions of a Martian soil analogue, JSC Mars-1, spiked with a range of standards show that a 20:80 (vol:vol) mixture of methanol and water is incapable of extracting compounds insoluble in water. However, addition of 1.5 mg ml⁻¹ of the surfactant polysorbate 80 produces extraction efficiencies of the aliphatic standards, hexadecane and phytane, equal to 25-30% of those produced by the common organic solvent mixture 93:7 (vol:vol) dichloromethane:methanol. Extraction of squalene and stigmasterol using the polysorbate solution is less efficient but still successful, at 5-10% of the efficiency of 93:7 dichloromethane:methanol. Such aliphatic compounds with occasional functional groups represent the compound classes to which most fossil organic biomarkers belong. The polysorbate solution did not extract the aromatic compounds pyrene and anthracene with great efficiency. A solvent of 20:80 methanol:water with 1.5 mg ml⁻¹ polysorbate 80 is therefore capable of selectively extracting aliphatic biomarkers from Martian samples and transferring them to the antibody sites on the life marker chip.     

基于二元水循环的河流生态需水水量与水质综合评价方法——以辽河流域为例

In this article the meaning of the quantity and quality of environmental flows of river in dualistic water cycle is discussed,and compared with the meaning of unitary water cycle. Based on the analysis of the relationship between environmental flows of river re-quirements,the efficiency of water resource usage,the consumption coefficient,and the concentration of waste water elimination,the water quantity and water quality calculation method of the environmental flows of river requirements in dualistic water cycle is developed,and the criteria for environmental flows of river requirements are established,and therefore the water quantity-quality combined evaluation of natural river flows requirements are realized. Taking the Liaohe River as a model,the environmental flows of river requirements for Xiliao River,Dongliao River,mainstream Liaohe River,Huntai River and northeast rivers along the coasts of the Yellow and Bohai seas in unitary water cycle are calculated,each taking up 39.3%,63.0%,43.9%,43.3% and 43.5% of runoff respectively. Evaluated according to Tennant recommended flow,the results show that: except Xiliao River is "median",the rest are all upon "good",the Dongliao River is even "very good". The corresponding results in dualistic water cycle are that,the proportion of natural flows for each river is 57.5%,74.1%,60.8%,60.3% and 60.4%; while the combined evaluation results show that: considering "quantity",except Xiliao River,the rest rivers can all achieve the "quantity" criteria of the en-vironmental flows of river requirements,but if considering the aspect of "quality",only Dongliao River can reach the "quality" standard. By water quantity-quality combined evalua-tion method,only Dongliao River can achieve the criteria. So the water quality is the main factor that determines whether the environmental flows can meet the river ecosystem de-mands.     

气候变化对中亚草地生态系统碳循环的影响研究

准确评估草地生产力、碳源/碳汇功能,分析气候变化对草地生态系统碳循环的影响,对于草地资源的合理开发和有效保护至关重要。选取对气候变化以及人类干扰高度敏感的中亚干旱区草地生态系统为研究对象,利用Biome-BGC模型,模拟分析其NPP、NEP的年际变化趋势及其空间分布格局。结果显示：（1）1979-2011年中亚地区草地生态系统NPP年平均值为135.6 gC·m^-2·a^-1,且随着时间的推移呈现出波动下降的趋势,下降速率为0.34 gC·m^-2·a^-1。（2）NEP的年平均值为-8.3 gC·m^-2·a^-1,表现为碳源,且该值随着时间的推移呈现出波动上升的趋势,上升速率为0.58 gC·m^-2·a^-1。（3）NPP高值区域在降水较为丰富的天山山脉附近以及哈萨克斯坦北部。（4）NPP的年际变化与降水量的年际变化趋势基本一致,相关系数为0.52;NPP与温度的相关系数为-0.28,未达到显著相关水平。本研究实现了Biome-BGC模型在中亚干旱区草地生态系统的应用,对评价干旱区草地生态系统碳源/碳汇功能及其在全球碳循环和全球变化中的作用、实现中亚草地生态系统的可持续利用、完善区域和全球碳循环理论体系具有重要意义。     

Ontogenetic patterns of concentration indicate lagoon nurseries are essential to common grunts stocks in a Puerto Rican bay

Estimates of abundance and size of three commercially exploited grunt species indicate ontogenetic changes in habitat utilization concentrate their juveniles within the lagoon of the Bay of La Parguera, Puerto Rico. Eleven biotopes, defined by four benthic structures (reef, mangrove, vegetation beds and unconsolidated sediments) and three geographic zones (inner lagoon, outer lagoon and bank shelf) were sampled randomly by visual surveys. French, bluestriped and white grunt (Haemulon flavolineatum, Haemulon sciurus and Haemulon plumeri) were common in the bay and appeared to exhibit similar life history patterns of cross-shelf migration and habitat selection. Recently settled grunts were dispersed over vegetated and unconsolidated soft-bottom sediments of the bay. The juvenile stage occurred in highest densities in shallow lagoon biotopes among the submerged prop-roots of mangrove stands and on inshore reefs. Length data indicates that grunts migrate offshore to adult habitat via increasingly deep reefs. Indices of biotope nursery function based on standing stock estimates of juveniles identified three biotopes, all within the inner lagoon as essential habitat for juveniles of 5–10 cm length interval. This concentration of juveniles within biotopes of the lagoon could represent a bottleneck to recruitment for grunt stocks. Evidence that quantity and quality of lagoon nurseries may limit recruitment indicates that these areas represent a key component of a marine protected area designed to restore fisheries within the bay.     

新时代面向美好生活的日常生活地理与城乡休闲——“生活地理与城乡休闲”专栏解读

随着西方学界“日常生活”的兴起与转向,“回归生活世界”与生活本体论成为人文地理学研究的新视角。新时代背景下,中国社会主要矛盾的转化催生地理学人地关系的转变,由静止的、同质的人地关系转变为动态的、异质的人地互动关系,“人”与“地”被赋予日常生活的内涵与外延,“闲暇处才是生活”。在追求美好生活的新时代,地理学需要回答日常生活地理以及休闲具有哪些地理特征,不同主体如何通过日常生活及休闲展演人与地、人与人、人与自我的动态关系,从而建构不同空间尺度的生活实践与地方意义等问题。本专栏主要探讨日常生活及休闲中所展演的主体能动性、空间异质性以及人地互动的复杂性,涉及城市居民的生活休闲与主观幸福感、城市公共空间活力评价以及休闲方式、日常生活中的地方情感与定居意愿等内容,以期尝试用中国本土的实证来回应西方日常生活地理学的研究。期待未来的相关研究能够更加关注边缘群体的日常生活及其休闲,能够弥补城乡休闲中“乡”尺度的不足,能够全面系统地阐述日常生活与休闲在时间演变过程中的变化规律及其机制。专栏旨在推动中国情境的日常生活地理学的理论建构,在实践上以期为新时代美好生活的具体践行贡献地理智慧。     

Aspects of Assaying Sediment Toxicity in Irish Estuarine Ecosystems

The toxicity of surface sediments collected from eight estuarine sites around the Irish coast was assessed in March 1997 using a whole sediment bioassay. Two molluscan species, Tapes semidecussatus (1 + age class) and Scrobicularia plana (unknown age) were exposed to test sediments for 21 days. Survival, morphometric, behavioural and histochemical measurements were taken during the 21 day bioassay. 100% mortality occurred in both species in sediments from one site in Dublin Bay within 18 days of initial exposure. 100% survival of T. semidecussatus was observed in all but four of the test sediments to which it was exposed during this study. The animal condition and wet tissue weight of T. semidecussatus decreased for all sediments during the bioassay. 95% survival of S. plana was observed after 21 days exposure to Youghal (reference) sediment. Condition and wet tissue weight of S. plana increased in all test sediments during the bioassay, however, there was significant variation in wet tissue weight of this species on day 25 of the bioassay in all test sediments. There was significant variation in the burrowing behaviour of S. plana during the bioassay. Lipofuscin accumulation was observed in the digestive diverticula of T. semidecussatus exposed to all test sediments with the exception of Youghal (reference). The potential for both species as bioassay organisms is discussed.     

绿潮生物学机制研究

绿潮发生机制极其复杂,但其核心机理是绿潮暴发时漂浮"藻席"中的浒苔快速形成巨大生物量,涉及浒苔生物学过程对环境的响应及其生理生化基础。为此,本文在已有研究报道的基础上,对浒苔生活史研究进行了充分的理论补遗;分析了漂浮"藻席"中浒苔生长与繁殖过程,认为该过程是绿潮生物量形成的关键;阐述了浒苔孢子囊形成是对富营养化背景下海水溶解无机氮(DIN)中硝态氮高占比的响应,认为一氧化氮分子可促进浒苔营养细胞向孢子囊的转化;解析了浒苔细胞对逆境因子的响应途径与机制。基于已有的研究成果,本文对浒苔引发绿潮的生物学过程进行了理论推定。人为或自然因素使固着浒苔处于漂浮状态,形成小规模"藻席";富营养化背景下海水DIN中硝态氮占比的升高赋予了浒苔巨大的繁殖潜能,漂浮过程溶解无机碳(DIC)"充裕"和"不足"两个阶段的交替以及食藻动物啃食产生的藻片段使孢子囊形成比例大幅提升;孢子原位萌发等使释放的孢子在"藻席"中获得了附着基,个体数目随之指数增长;结合漂浮浒苔的高生长速率,"藻席"规模不断扩大,短时间内形成巨大生物量。同时,本文还对今后的绿潮研究提出一些建议,认为啃食动物在浒苔生物量消长过程中发挥重要作用,在...     

血卵涡鞭虫感染三疣梭子蟹的病原形态学及组织病理学变化

血卵涡鞭虫是一类主要感染海产甲壳类的致病性寄生性甲藻。近年来,该寄生性病原在我国沿海主要经济蟹类养殖区域流行性发病,给当地蟹类养殖业造成了严重经济损失。为厘清血卵涡鞭虫的生活史形态,了解宿主的病理损伤机制,本文通过血涂片法和HE染色法系统研究了感染过程中该寄生虫的形态变化和宿主的组织病理变化。结果表明,血卵涡鞭虫在感染过程中经历丝状滋养体、单核/双核/多核滋养体、团聚体、蛛网状滋养体、孢子前细胞及孢子等不同生活史阶段。感染导致三疣梭子蟹发生系统性病理变化,肝胰腺、心脏、鳃、肌肉等器官和组织在不同感染阶段均发生相应程度的组织病理变化,主要表现为体细胞破损或坏死、细胞间隙模糊、疏松结缔组织充斥大量寄生虫细胞。最终由于寄生虫在宿主主要器官组织间隙内大量增殖,导致重度感染的梭子蟹器官或组织功能破坏、丧失而死亡。     

臂轮凹口虫新种及其生活史的研究

于1979年7月在武昌中国科学院水生生物研究所湖汊采集水草,经研究发现须根上栖息的轮虫体内有一种专门攻击萼花臂尾轮虫和双棘臂尾轮虫的凹口虫,经鉴定系一新种,其主要特征为,传布子长椭圆形,两端较尖小,中间稍微凹;体前方有锥形的钻孔器,后端有3—5根长尾毛;大核香肠状,小核一个,椭圆形,伸缩泡一个,居中偏后。营养子圆球形,直径78—141μm,大核肾形,小核和伸缩泡各一个,亦具尾毛;裂子数为2—32个。寄生。致死轮虫,并在轮虫躯壳内完成其生活史。能形成次级包囊和抵抗性包囊。     

典型黄土塬区地下水水化学成因机制及碳循环意义

水岩相互作用包括了溶解、沉淀和离子交换等作用, 其参与了各种地质作用和生态-环境过程; 而目前对离子交换作用在水中离子来源解析和同位素示踪等方面考虑不足, 这限制了对水化学演化规律和碳循环刻画等方面的认识。本研究选择水文地质条件较为简单的甘肃陇东地区董志塬, 在对降水入渗补给评估、地下水定年(³H和¹⁴C)等水循环规律刻画的基础上, 通过对降水元素输入和阳离子交换容量分析, 以及应用硝酸盐同位素(δ¹⁵N-NO₃和δ¹⁸O-NO₃)、硫酸盐同位素(δ³⁴S-SO₄和δ¹⁸O-SO₄)、⁸⁷Sr/⁸⁶Sr (包括地下水及黄土各分量)、阳离子关系等手段, 解析了董志塬地下水中主要离子来源。研究结果显示, 降水入渗补给量为39±8mm/a, 土壤水运移速度为0.13±0.03m/a; 研究区包气带较厚(主要在40~75m), 这说明年降水需要250~750年才能补给到地下水, 但持续的补给使得自然条件下每年约有(3167±650)×10⁴m³地下水通过泉水补给两侧河流。地下水年龄较老, 不含³H, ¹⁴C校正年龄在417年至19420年之间, 因此水化学组成受现代人类活动影响可忽略; 地下水中Cl^-和SO₄^2-主要来自于古降水, 并反演出古降水SO₄^2-平均含量为1.2mg/L, 显著低于受化石燃料等影响的现代含量(平均为6.6mg/L); 而地下水NO₃^-则主要来自于土壤氮的硝化。地下水⁸⁷Sr/⁸⁶Sr比值(0.7107至0.7114)与黄土中碳酸盐的比值(0.7103至0.7111)基本一致, 表明Ca²⁺和Mg²⁺主要来自于碳酸盐矿物的溶解, 部分被吸附至粘土矿物。研究区黄土具有较高的阳离子交换容量(149±33meq/kg), 地下水总Na⁺中, 降水贡献平均占29%, 其余Na⁺主要来源于水中Ca²⁺和Mg²⁺和粘土矿物中Na的交换(平均为71%), 硅酸盐溶解对水中Na⁺贡献可忽略(硅酸盐溶解会导致⁸⁷Sr/⁸⁶Sr增加), 而以往研究大多认为除了降水输入、蒸发岩溶解外, 水中Na⁺主要来自于硅酸盐矿物的溶解, 并贡献了碳汇。本研究认为在研究区地下水中, 硅酸盐风化的碳汇效应可忽略; 同时强调了在含有粘土矿物的流域或水岩体系, 阳离子交换作用在示踪水中离子来源及碳循环中的重要性。