Decomposition and alteration of organic compounds dissolved in seawater

The dissolved organic matter in seawater is grouped into two fractions which are defined as having greatly differing reactivities with respect to both chemical and biological decomposition. One fraction, which constitutes the bulk of the material, is extremely stable and inert and is only slowly degraded by either chemical or biological processes. The other fraction, which is composed of trace organic compounds derived from living organisms, contains components such as free amino acids which are rapidly degraded, probably by marine organisms which use these compounds as a food source. Conclusions about the cycle of organic compounds in seawater based on total organic carbon concentrations could thus be misleading, since pathways involving labile trace organic constituents would be completely obscured. Investigations of the distribution, concentration, and possible diagenetic reactions of specific organic compounds are necessary in order to elucidate the cycle of these compounds in the oceans.     

Arsenic,barium, germanium,tin, dimethylsulfide and nutrient biogeochemistry in Charlotte Harbor,Florida, a phosphorus-enriched estuary

Concentrations of dissolved nutrients (NO₃, PO₄, Si), germanium species, arsenic species, tin, barium, dimethylsulfide and related parameters were measured along the salinity gradient in Charlotte Harbor. Phosphate enrichment from the phosphate industry on the Peace River promotes a productive diatom bloom near the river mouth where NO₃ and Si are completely consumed. Inorganic germanium is completely depleted in this bloom by uptake into biogenic opal. The $\text{Ge}\text{Si}$ ratio taken up by diatoms is about 0·7 × 10^?6, the same as that provided by the river flux, confirming that siliceous organisms incorporate germanium as an accidental trace replacement for silica. Monomethylgermanium and dimethylgermanium concentrations are undetectable in the Peace River, and increase linearly with increasing salinity to the seawater end of the bay, suggesting that these organogermanium species behave conservatively in estuaries, and are neither produced nor consumed during estuarine biogenic opal formation or dissolution. Inorganic arsenic displays slight removal in the bloom. Monomethylarsenic is produced both in the bloom and in mid-estuary, while dimethylarsenic is conservative in the bloom but produced in mid-estuary. The total production of methylarsenicals within the bay approximately balances the removal of inorganic arsenic, suggesting that most biological arsenic uptake in the estuary is biomethylated and released to the water column. Dimethylsulfide increases with increasing salinity in the estuary and shows evidence of removal, probably both by degassing and by microbial consumption. An input of DMS is observed in the central estuary. The behavior of total dissolvable tin shows no biological activity in the bloom or in mid-estuary, but does display a low-salinity input signal that parallels dissolved organic material, perhaps suggesting an association between tin and DOM. Barium displays dramatic input behavior at mid-salinities, probably due to slow release from clays deposited in the harbor after catastrophic phosphate slime spills into the Peace River.     

How conservative is arsenic in coastal marine environments? A study in Irish coastal waters

The conservative potential of arsenic in the relatively pristine waters of Galway Bay, an estuarine system in the west of Ireland, is examined through the inter-seasonal variations in the distribution of its total, hydride and non-hydride fractions. The arsenic concentrations in Galway Bay and local fresh water sources at all seasons were lower than what is considered the natural seawater concentration of 2 μg L⁻¹ (27 nM). The effects of physical mixing, biological uptake and regeneration of arsenic on its distribution are considered. The degree of biological uptake and regeneration of the element are determined by a first order speciation between total arsenic (a small part of which should be of organic origin) and hydride arsenic (mostly of inorganic origin). The structural similarity of arsenic species to phosphate in seawater causes arsenic to be taken up by biota, which then have to detoxify it, so results are presented against phosphate to determine the degree of biological transformation of arsenic at different seasons. An in-house, batch type system of hydride generation coupled to electro-thermal atomic absorption spectrometry is used for the analysis of arsenic; this is preceded by UV-digestion prior to the measurement of total arsenic. Results show only a small association of arsenic with phosphate but a near linear, positive distribution pattern between arsenic and salinity in Galway Bay (R² ∼ 0.6), which is reproducible among seasons, indicating that in this environment the biological uptake of arsenic is likely to be a much slower process than the physical mixing of the water masses.     

关于我国海洋生物资源领域科技布局的若干思考

我国蕴藏着丰富的海洋生物资源,海洋生物资源的可持续利用是全球科技创新中最具实效性和创新性的领域之一。介绍了"十一五"期间我国在海洋生物领域的科技布局和成果产出;分析了我国海洋生物领域科技发展的制约因素:理论体系不完善、稳定经费投入不足、科研平台支撑能力薄弱、人才队伍培养力度不强、产品集成开发亟待提升;提出了海洋生物领域科技发展战略对策和建议:关注重大基础性科学问题和技术问题、加大科技投入和提高利用效率、重视科研条件平台建设、引进高水平领军人才和培养中青年科研骨干、重视新型海洋生物制品的研发和宣传。     

The behaviour of dissolved arsenic in the estuary of the River Beaulieu

The chemical forms and distribution of dissolved arsenic species in the estuary of the River Beaulieu (Hampshire, U.K.) are reported. ‘Inorganic arsenic (V)’ in both the marine and riverine estuary inputs are in true solution, passing through ultrafiltration membranes having a nominal molecular weight cut-off of 500 daltons. Extensive removal of dissolved ‘inorganic arsenic (V)’ is apparent from the distribution of arsenic in the estuary, with laboratory mixing experiments indicating that removal is favoured in the low salinity region. ‘Inorganic arsenic (III)’ and methylated arsenic species account for up to 41% and 70% of the dissolved arsenic, respectively, but are only found during the warmer months when water temperatures exceed ca. 12°C.     

Behaviour of arsenic on the continental shelf off the Gironde estuary: Role of phytoplankton in vertical fluxes during spring bloom conditions

The arsenic (As) cycle in the marine environment is known to be sensitive to biological activity. Within the scope of the National Coastal Oceanography Program, we undertook a specific study of the behaviour of this element in a water column on the continental shelf of the Bay of Biscay off the Gironde estuary during two oceanographic cruises conducted in May 1994 and May 1995. Various chemical forms were measured: arsenate (As3), arsenate (As5), monomethylarsenic (MMA), dimethylarsenic (DMA) and dissolved total As after ultraviolet mineralization. The net flux of total As from the Gironde estuary was evaluated as well as its effect on the concentration in surface marine waters. The vertical profiles in the coastal zone during a period of active primary production confirmed a certain analogy between arsenates and phosphates as well as the formation of As3 and DMA. The importance of organoarsenic species not directly accessible to the formation of volatile hydrides is demonstrated. Their presence modifies assessments, reducing the deficit of dissolved total As in the euphotic layer to just 5%. For particles, the As content in phytoplankton was estimated at 6 μg·g⁻¹ compared to 20 to 30 μg·g⁻¹ in iron- and aluminium-rich terrigenous particles. These results do not invalidate the role of phytoplankton in the speciation of dissolved As but indicate that their involvement in vertical transfers was apparently not predominant in the zone under study.     

海洋浮游细菌生长率和被摄食的研究综述

海洋浮游细菌利用海水中的溶解有机碳合成自身物质,是海洋浮游生态系统的二次生产者。微型浮游动物是细菌的主要摄食者,也是细菌生产向较高营养级传递的中介。研究海洋浮游细菌的生长率和被(微型浮游动物的)摄食率对理解海洋浮游生态系统的功能具有重要作用。本文综述了利用改变海水中生物类群组成(或功能)的培养方法研究海洋浮游细菌生长率和被摄食率的历程和现状,为我国的同类研究提供借鉴。改变海水中生物类群组成(或功能)进行培养的方法有海水分粒级培养、海水稀释培养和添加选择性抑制剂培养。这些方法各有其局限性,应用并不广泛。细菌及其主要摄食者异养鞭毛虫群落在自然海区和实验室内都有生长周期,鞭毛虫的生长周期落后于细菌,因此细菌的生长率有时会小于被摄食率,有时会大于被摄食率。我国这方面的研究相对落后,应值得引起重视,建议从海水稀释培养法入手开展相关研究。     

黄河口区及挑河口区若干海洋生物体内砷的含量

作者测定了1984年从黄河口区和挑河口区采集的十九种海洋生物的砷含量。把这些测定结果同水样及沉积物分析数据结合起来,结果表明该区尚未受到砷污染。     

典型自然源气溶胶沉降引起的海洋初级生产响应

大气沉降是陆源物质向海洋输入营养盐的重要方式,沙尘、野火和火山喷发均能够产生气溶胶,这些典型的自然源气溶胶在风场的作用下,能够进行远距离的输运,期间由于沉降作用进入海洋,为上层海洋提供限制性营养盐促进海洋浮游植物生长,提升海洋的初级生产力,促进碳循环过程。以海表叶绿素浓度作为海洋初级生产力的重要指标,通过海表叶绿素浓度的响应,探究沙尘、野火和火山这三种典型自然源气溶胶的传输路径及其沉降对海洋初级生产的影响。结果显示,海洋初级生产对气溶胶沉降的响应不仅与气溶胶排放类型有关,也与温度、动力过程、光合有效辐射等海域初级生产影响因素有关,体现了海洋初级生产对自然源气溶胶的敏感性,自然源气溶胶沉降所驱动的海洋初级生产在全球碳循环中具有重要的潜在影响。     

福建闽南沿海养殖贝类体中砷含量的分布

通过2003~2004年对福建闽南沿海5种养殖贝类体砷含量的调查监测,对养殖贝类体中砷含量的分布进行了探讨.福建闽南沿海5种养殖贝类体总砷含量为0.65×10-6~4.80×10-6,总平均值为2.09×10-6,其中有机砷和无机砷占总砷含量的百分比分别为61.6%~98.2%和2.3%~38.4%,平均值分别为88.8%和11.2%.在相同养殖区,养殖贝类体总砷平均含量的种间分布差异较小.滩涂养殖底栖贝类体内总砷平均含量总体上高于浅海筏式养殖贝类体的平均含量.福建闽南沿海5种养殖贝类体内总砷含量在泉州湾、湄州湾、东山湾和九龙江口高,在诏安湾和围头湾低,在其余各湾相近.5种养殖贝类体内无机砷的污染指数和总平均值分别为0.05~0.76和0.23,总砷的污染指数和总平均值分别为0.06~0.48和0.21,总体符合国家食品卫生质量标准.养殖贝类体中砷含量与体长之间总体成正相关.     

Calcareous algae bioclast contribution to sediment enrichment by arsenic on the Brazilian subtropical coast

Arsenic levels (up to 130 mg kg⁻¹) substantially exceeding the official threshold have recently been documented in beach and nearshore sediments along more than 50 km of coastline in the Brazilian state of Espírito Santo between 19°50′ and 20°12′S. In an attempt to assess the sources of this enrichment, we performed a study on arsenic distribution in the main mineral substances and living organisms in the beach environment. Laboratory tests on arsenic retention by beach carbonate debris have also been carried out. The data suggest that sedimentary arsenic occurs largely bound to particles of the calcareous red alga Corallina panizzoi, whereby live specimens contained much smaller amounts of this metalloid than was the case for nonliving material (2.4 and 20.3 mg kg⁻¹, respectively). Experimental tests confirmed the ability of C. panizzoi detritus to retain arsenic at pH intervals and ionic strength characteristic of seawater. There are two potential sources of that metalloid for calcareous debris in sediments: brown macroalgae, which were found to contain high levels of As (up to 66.3 mg kg⁻¹), and ferruginized sandstones (up to 23.0 mg kg⁻¹). We argue that any contribution of brown algae to beach sediment enrichment by As would be minor, and consider the ferrous sandstones from coastal sedimentary rocks of the Barreiras Group as the principal large-scale source of arsenic in the marine environment of Espírito Santo. The experimental data, together with field studies, corroborate the interpretation that arsenic anomalies in sediments with calcareous debris can form when weathered continental rocks even only slightly enriched in As are leached by marine waters, and the As is at least partially retained by biogenic calcareous detritus in nearshore sediments. Considering that rocks of the Barreiras Group are exposed to marine erosion far to the north of Espírito Santo, we estimate that marine sediments containing calcareous material are “anomalously” enriched in As along approximately 2,000 km of the Brazilian tropical coastline.     

Chemical speciation of arsenic in different marine organisms: Importance in monitoring studies

Arsenic is a widely distributed element in the marine environment. Inorganic and organic compounds have extremely different toxicological effects, and their characterization is thus of great utility when monitoring and assessing the impact of arsenic pollution. In this study both the levels of total arsenic and its chemical speciation were analyzed in several marine organisms collected from Cienfuegos Bay (Cuba) following an episode of acute As-contamination. Fish from the more impacted site were characterized by elevated concentrations of arsenic (up to 500 microg/g d.w.) and inorganic species represented the predominant forms in muscle tissues of these organisms.     

山东近岸海域表层沉积物7种重金属污染特征和生态风险评估研究

本文综合运用单因子污染指数法、Hakanson潜在生态风险指数法和沉积物质量基准法3种方法,研究和评价了2012年和2013年山东近岸海域表层沉积物重金属的污染特征和潜在生态风险。结果表明:山东近岸海域94%以上站位的表层沉积物重金属含量符合第一类海洋沉积物质量标准,沉积物质量良好;山东近岸海域重金属综合潜在生态风险低,各重金属潜在生态风险由高到低为HgAsCdPbCuCrZn(2012年)和HgCdAsPbCuCrZn(2013年),Hg在个别站位达中潜在生态风险程度,为主要污染因子;50%以上站位As含量介于美国佛罗里达州和加拿大沉积物质量基准的TEL—PEL之间,表明负面生物效应偶尔发生。应加强对山东近岸海域表层沉积物中重金属Hg和As的监测,重点关注二者相对高值区的潜在生态风险和负面生物效应。     

海洋浮游植物初级生产力及碳生物量的检测技术研究进展

浮游植物是海洋生态系统中的主要初级生产者，构建海洋食物网、生物泵和元素循环（包括碳循环、氮循环和硅循环等）的基石。因此，海洋生态系统中的元素循环和能量流动均与浮游植物的生长和代谢息息相关。海洋碳循环是全球碳循环的关键环节，也是全球生态系统中生物地化循环的重要组成部分。尽管浮游植物在海洋碳循环中起着至关重要的作用，但是直接测定浮游植物的初级生产力和碳生物量依旧受到传统技术和方法的限制。本文详细介绍了有关浮游植物初级生产力和碳生物量检测的各种技术和方法，列举了其各自的优缺点。目前，测定海洋浮游植物初级生产力的主要方法有黑白瓶法、遥感估算法、碳同位素测定、快速重复率荧光法；测定海洋浮游植物碳生物量的主要方法有细胞体积转换法、流式细胞术、电子探针X射线显微分析、分位数回归模型估算法。通过对比分析发现碳同位素与快速重复率荧光法相结合可以更高效测定出初级生产力，而最具优势与应用前景的碳生物量检测方法是基于分位数回归模型估算法。其中，基于分位数回归模型估算法具有拟合异常值、测定结果准确等优势，能够实现现场浮游植物群落以及各个功能群碳生物量的估算，并能够与卫星遥感技术手段相结合，可以应用于大尺度和长时间序列的海洋浮游植物碳生物量估算。通过本文的综述，一方面为海洋浮游植物初级生产力和碳含量的研究提供一个基本和系统的认识，另一方面为深入研究浮游植物在海洋碳循环以及全球碳循环中的作用提供参考。     

Biogeochemical processes affecting total arsenic and arsenic species distributions in an intermittently anoxic fjord

Total arsenic, arsenate and arsenite concentration profiles for the water column of Saanich Inlet, an intermittently anoxic fjord located on Vancouver Island, B.C., Canada, were measured using independent analytical techniques for total arsenic and arsenic speciation to evaluate the accuracy of the speciation technique in both oxic and anoxic marine environments. Total arsenic profiles indicate a mid-depth minimum of about 1.0 ppb above the oxic—anoxic interface and an enrichment in the anoxic zone to about 2.0 ppb. This minimum may be due to either advection of arsenic-poor water into Saanich Inlet at mid-depth or arsenic incorporation onto solid phases within a bacteria- and manganese-rich particulate layer located immediately above the oxic—anoxic interface and subsequent removal via sinking particulate material. Ratios of total arsenic to phosphorus in the deep, anoxic waters of the basin are similar to those reported for marine algae, suggesting that the enrichment of total arsenic within the anoxic bottom layer may be due to its release upon organic matter decomposition.Arsenate and arsenite concentration versus depth profiles indicate a rapid (but incomplete in a thermodynamic sense) response to the oxic—anoxic interface. The arsenate/ arsenite concentration ratio is 15/1 in the oxic region of the water column and 1/12 in the anoxic zone. Arsenate—arsenite interconversion occurs at a depth shallower than ferric-ferrous but deeper than MnO₂ —Mn²⁺ interconversions.Measurements of arsenite oxidation rates at near-ambient arsenite concentrations and temperatures using an ⁷⁴As³⁺ radioactive tracer technique indicate that arsenite oxidation is initially ten times faster in seawater taken from the manganese-rich particulate layer at 165 m depth than in seawater collected near the surface at 50 m depth. Addition of antibiotics to seawater from 165 m depth initially suppressed the rate of arsenite oxidation, indicating that it may be partially microbially mediated.     

海洋生物固氮速率与影响因素的研究进展

海洋生物固氮是指固氮生物利用固氮酶将氮气转化为生物可利用铵盐的海洋氮元素输入过程,和反硝化及厌氧氨氧化等氮流失途径一起制约着大洋氮收支平衡。而固氮速率的测定是研究海洋生物固氮的最直接方式。自发现海洋生物固氮作用以来,固氮速率的测定方法在不断更新改进,但总体来说仍存在较大不确定性。最近用¹⁵N₂同位素示踪法及其他相关数据综合得到全球海洋固氮量为196.1 Tg N∙a⁻¹,最高固氮速率发生在南太平洋热带地区。但分布受到多种因素的影响。其中,物理因素中的光照和温度是全球范围固氮速率分布的最佳预测因子,光照为固氮过程提供能量,温度通过影响固氮酶活性而发挥作用。在化学因素中,铁元素的缺乏成为固氮的重要限制因子。除此之外,还有生物因素,如浮游植物和异养固氮生物等,对固氮量的贡献影响较大。最近有研究对以往固氮作用区域和反硝化作用空间相互耦合的观点表示质疑,提出二者分布空间分离的新格局。研究多控制因素对固氮生物的耦合效应、明确不同物种对固氮总量的相对贡献以及进一步建立固氮速率的原位测定方法是未来海洋固氮作用研究的主要工作。     

海洋生物声散射层研究现状综述

海洋生物声散射层全球分布广泛,其昼夜垂直迁移机制与周围海水的物理特性息息相关,对海洋内部碳的循环具有重要作用。文章收集整理了海洋生物声散射层的昼夜垂直迁移现象在各领域上的研究方法及研究成果,包括国内外研究现状,散射层的声学探测手段、全球范围内的分布变化情况等。海洋生物声散射层渔业资源丰富,研究和探索散射层有助于我们了解海洋物理环境和当地海洋渔业资源分布,对渔业资源的开发和利用具有重要意义。     

国际背景下的海洋调查技术标准化发展路径研究

通过对比分析我国与美国、欧盟的标准战略、标准化组织机构、标准体系和海洋调查技术标准具体的制订现状,综合比较了我国与发达国家之间的差异,建议借鉴以民间自由竞争为特点的美国标准模式和以高度国际化的标准体系为特点的欧洲标准模式,同时充分发挥国际标准化组织海洋技术分委会(ISO/TC8/SC13)主席和秘书处落户中国这一平台优势的桥梁作用,探索我国海洋调查技术标准国际化的有效路径。     

Marine systems: moving into the genomics era

The study of biological systems has been revolutionized by the use of genomic technologies. Most of the knowledge gathered over the last few years refers to terrestrial models. The study of marine systems using genomic technologies has, apart from a focus on microbial systems, been generally neglected although there are signs that this situation may be changing. This review analyses recent progress made in the field of marine genomics and identifies the broad areas in which this new technology is having the greatest impacts. These studies include comparative, functional and environmental genomics of metazoan animals. In many cases, as well as benefiting marine science, studies on marine taxa are having wide‐ranging impacts on our global understanding of genomes and genomics.     

海洋碳汇作用机理与发展对策

为应对全球性气候变化,提高对海洋碳汇的科学认知,文章介绍海洋碳汇及其碳循环模式,分析海洋碳汇面临的困境,并提出相关建议。研究结果表明:碳分为黑碳、褐碳、绿碳和蓝碳4种类型,其中蓝碳即海洋碳汇,即通过海洋固定和储存二氧化碳,是全球碳循环的重要机制;海洋碳汇由溶解度泵、生物泵和微型生物泵3种碳泵共同完成,其中依赖海洋微生物的微型生物泵储碳效率最高;海洋碳汇正面临生境基础退化和海洋酸化加剧的问题,未来应针对问题加强政策性管理和保护以及加强科学技术研究和实践。