海水中氨基酸对Cu（Ⅱ）在r—MnOOH上吸附的影响

实验测定了海水中氨基酸存在下Ｃｕ（Ⅱ）在ｒ－ＭｎＯＯＨ上吸附的等温线、Ｃｕ（Ⅱ）％－－ｐＨ曲线和Ｃｕ（Ⅱ）％－氨基酸深度曲线。结果表明，较低浓度氨基酸对Ｃｕ（Ⅱ）在ｒ－ＭｎＯＯＨ上吸附没有影响，而较高浓度氨基酸却起抑制作用，这主要是由于海水中Ｃｕ（Ⅱ）－氨基酸络合反应与ｒ－ＭｎＯＯＨ竞争Ｃｕ（Ⅱ）所致。此外，海水中较高浓度氨基酸只使Ｃｕ（Ⅱ）在ｒ－ＭｎＯＯＨ上吸附的表面分级离子交换稳定常数Ｋｉ（ｉ     

Molecular characterization of organic matter in sediments from the Keg River formation (Elk Point group), western Canada sedimentary basin

Distributions of free and sulfur-bound biomarkers in organic-rich sediments from the lower and upper Keg River formation (Elk Point group, western Canada) reveal deposition of these sediments under reducing conditions, in agreement with the geological data. The predominance of aryl isoprenoids of Chlorobiaceae origin indicates that photic zone anoxia occurred during time of deposition. A series of novel aryl isoprenoids with a carboxylic acid function was identified by GC–MS and the structure of the predominant 3-methyl-5-(2′,3′,6′-trimethylphenyl)pentanoate was proven by synthesis of an authentic standard. The occurrence of these acids gives evidence that oxidative breakdown at least partially accounts for the diagenetic fate of aromatic carotenoids. Li/EtNH₂ desulfurization of two kerogen concentrates yielded only low amounts of sulfur-bound hydrocarbons, and suggests that either sulfur sequestration was not a predominant process or, more probably, that a major part of the hydrocarbons, initially sulfurized, were released upon maturation, giving further evidence that (poly)sulfide bonds are cleaved at relatively low levels of thermal stress.     

Factors Influencing Nitrogen Speciation in Coastal Rainwater

Rainwater was collected from 129 rain events between February 2002 and August 2003 and analyzed for ammonium (NH₄⁺), nitrate (NO₃⁻), organic nitrogen (ON) and free amino acids (AA). Inorganic nitrogen (NO₃⁻ + NH₄⁺) was the dominant form of N representing 85% of total nitrogen based on volume-weighted averages. The remainder of the N occurred as organic nitrogen species of which free amino acids contribute approximately 17%. A significant, and in some cases the majority (> 75%), of the remaining ON could be accounted for by macromolecular uncharacterized humic like substances. This has important ramifications with respect to the long range transport of atmospheric ON because humic materials are recalcitrant and therefore may travel long distances from their source. There was a distinct seasonality to the N speciation data with maximum concentrations of NH₄⁺, ON and AA occurring in the spring. Air-mass back trajectory analysis indicates there is a strong anthropogenic component to the NO₃⁻, NH₄⁺ and AA signal but not ON. There was a strong positive correlation between amino acid concentrations and ammonium which suggests they have similar sources and sinks in rainwater. Finally, large episodic additions of NH₄⁺ and AA during tropical events could significantly impact short term bioavailable N budgets in estuaries impacted by these storms. Approximately three times as much NH₄⁺ and AA were deposited during Hurricane Isabel (317 μ moles ⋅ m⁻² and 84 μ moles ⋅ m⁻² respectively) compared to the mean impact of average summertime rain events at this location.     

Response of the soft coral Heteroxenia fuscescens to ultraviolet radiation regimes as reflected by mycosporine-like amino acid biosynthesis

The variation in mycosporine‐like amino acid (MAA) concentration in the soft coral Heteroxenia fuscescens in relation to changes in ultraviolet radiation (UVR) regimes was investigated at the Gulf of Eilat, northern Red Sea. Solar radiation (300–700 nm) was measured for different depths and seasons. The UVR irradiance was measured to a depth of 25 m on the reef. The mean attenuation coefficient for UV‐B measured in winter was twofold that of the summer value. Separation of H. fuscescens extracts by reverse‐phase isocratic high‐performance liquid chromatography revealed a single MAA compound, palythine (λ_max = 320 nm). Possible seasonal changes in MAAs in colonies of H. fuscescens along a depth gradient were examined on different dates. Palythine concentrations in the colonies were significantly higher in summer than in the other seasons particularly in shallow water. Possible changes in MAA content in colonies of H. fuscescens as a result of UVR protection, were determined by experiments conducted for periods of 1 week, 1 month and 3 months, at a depth of 5 m. In these experiments colonies were removed from the natural substrate and placed underwater, protected from UVR by a PVC filter. Significant differences between UV‐exposed and protected colonies of H. fuscescens were found only in the 3‐month experiment conducted during the summer. These findings demonstrate that UVR is an important environmental factor regulating MAA biosynthesis in the soft coral H. fuscescens.     

Impact of a scallop drag on the sediment chemistry, microbiota, and faunal assemblages of a shallow subtidal marine benthic community

Scallops are usually obtained by means of a heavy metal dredge that is pulled over the sea bottom. Most studies of the impact of this gear type have shown that larger invertebrates, in particular, are severely disturbed. These studies, however, have been conducted on coarse sediments, ranging from sands to cobble, and have dealt only with faunal changes. In this paper the impact of a New England type scallop dredge on the fauna and sedimentary nutritional characteristics of a silty sand community is detailed. The site, in the Damariscotta River, Maine, USA, was sampled during the fall and winter prior to, then again immediately following, the dragging event, and twice more over the ensuing six months. Loss of surficial sediment, lowered food quality of the sediment (as measured by microbial populations, enzyme hydrolysable amino acids, and chlorophyll a), and changes in the faunal composition of the dragged site were observed. While some taxa returned to the drag track relatively quickly, others such as the cumaceans, phoxocephalid and photid amphipods, and nephtyid polychaetes, were not seen in abundances comparable to those of the adjacent undragged site until the food quality also recovered.     

Comparative Morphology, Ecology, and Fatty Acid Composition of West Indian Spheciospongia (Demospongea)

Abstract. The morphological variability of the common West Indian loggerhead sponge, Spheciospongia vesparium, is examined in light of the latest morphological and ecological information and new biochemical criteria, that is, composition and concentration of fatty acids. A typical and a yellow ecophenotypical form are distinguished. Comparing this species with its next relatives in the same zoogeographical region it is found that S. othella, first described from Bermuda, cannot be maintained as a separate species. S. cuspidifera, previously misinterpreted as "Xestospongia tier-neyi", is confirmed as a distinct species of Spheciospongia, whereas "Prianos" tierneyi is considered a morphological variant of S. vesparium.     

光辐射对海洋微藻脂肪酸含量的效应

不同光辐射强度下三角褐指藻和小球藻脂肪酸的气相色谱分析表明 ,光辐射对海洋微藻脂肪酸的含量和组成影响很大。三角褐指藻和小球藻总多不饱和脂肪酸含量随着照度的增加呈下降趋势。在本实验条件下 ,在较低光强 (0 .2 5× 10 3 L ux～ 1.7× 10 3 L ux)时 ,EPA、DHA、C18∶ 3等多不饱和脂肪酸含量较高。     

锯缘青蟹幼体饵料蛋白质的营养价值评价

本文分析测定了锯缘青蟹幼体从刚孵化至大眼幼体各发育阶段及其饵料轮虫和卤虫无节幼体的氨基酸组成，并使用必需氨基酸指数(EAAI)来评价饵料蛋白质的质量.结果表明，青蟹各期幼体的氨基酸组成基本趋于一致，且与饵料转换不存在明显的相关性.对于各期幼体，饵料轮虫和卤虫无节幼体的必需氨基酸指数均大于90，可以认为，轮虫和卤虫无节幼体能够满足锯缘青蟹幼体对饵料中必需氨基酸的营养需求.     

Growth and photosynthetic rates of Chlamydomonas plethora and Nitzschia frustula cultures isolated from Kuwait Bay, Arabian Gulf, and their potential as live algal food for tropical mariculture

With a view to utilize local algae as food organisms in mariculture, the green alga Chlamydomonas plethora and the diatom Nitzschia frustula were isolated and studied from the unique coastal waters arid zone off Kuwait. Batch cultures of C. plethora and N. frustula had maximum division rates (μ_max) of 2.5 and 3.4 day^?1, respectively. Cultures grown for 36 h yielded comparable growth rates. Photosynthesis‐irradiance relationships in cultures harvested at various phases of growth showed that cultures attained log phase after 1‐day growth and yielded the highest assimilation numbers (P: μg C [μg Chl a]^?1 h^?1): 22.8 for C. plethora and 18.1 for N. frustula. Their initial slopes (α^B: ng C [μg Chl a]^?1 h^?1 [μmol m^?2 s^?1]^?1 were also the highest observed so far: 79.5 for C. plethora and 39.6 for N. frustula. Photoinhibition was low. Compared with these, assimilation numbers in senescent cultures of 20‐day growth were <8% of the maximum for both species, and the initial slope decreased to 17 and 13% in C. plethora and N. frustula, respectively. Two polyunsaturated fatty acids (20:5n‐3 eicosapentaenoic acid and 22:6n‐3 docosahexaenoic acid) that are essential in many marine animal diets constituted up to 24% and 1.9% of the total fatty acids, respectively. Of the two algae, N. frustula contained higher levels of 16:1n‐7, 20:5n‐3 and comparatively low levels of 22:6n‐3 fatty acids. Due to its rapid growth, high photosynthetic rate and presence of the amino acids leucine, lysine, glutamic acid and arginine N. frustula has good potential as a feed organism in mariculture applications. The capacity of these algae to produce a wide range of size groups (nano and net plankton) is an additional bonus for mariculture operations.