Dissolved oxygen in the Dead Sea— seasonal changes during the holomictic stage

Measurements of dissolved oxygen, density and temperature were con ducted in the Dead Sea between August 1987 and December 1989. Oxygen concentrations were found to vary around an average value of 0.8 mlSTP (standard temperature and pressure) per kg. Dissolved oxygen variations were found to reflect both physical processes (a deepening of the epilimnion, a turnover etc.) and chemical processes (oxidation reduction). Transport coefficients for the oxygen exchange across the air/sea interface were found to be generally low compared to expected values based on laboratory experiments; the presence of surface films which inhibit the gas exchange rates under calm weather conditions is suspected. During stormy weather, the exchange rates were considerably higher, suggesting that the entrainment of bubbles was involved in the gas exchange process. Contribution No. 95, Department of Environmental Sciences and Energy Research. The Weizmann Institute of Science     

酸性溶液中电位法测定理离子

本文在醋酸镁介质中，盐酸溶液形成缓冲溶液后，采用Ｌｉ＋离子选择性膜电极研究了ｐＨ值、ＭｇＣｌ２、ＮａＣｌ和ＫＣｌ对电极响应的影响，得到良好的效果．本法可应用于含ＭＳＣｌ２、ＮａＣｌ和ＫＣｌ的盐酸水溶液体系中锂离子浓度的测定．     

Significance of bacteria in carbon fluxes in the Arabian Sea

In the Arabian Sea, temporal contiguity of highly oligotrophic and eutrophic periods, along with high water temperatures, may result in unique features of bacteriaorganic matter coupling, nutrient cycling and sedimentation, which are unlike those in the classical oligotrophic and eutrophic waters. Bacteria-phytoplankton interactions are suggested to influence phytoplankton aggregation and its timing. It is also hypothesized that, within aggregates, hydrolytic ectoenzyme activity, together with condensation reactions between the hydrolysis products, produce molecular species which are not readily degraded by pelagic bacteria. Accumulation of a reservoir of such slow-to-degrade dissolved organic carbon (DOC) is proposed to be a carbon flux and energy buffer, which moderates the response of bacteria to the dramatic variations in primary production in the Arabian Sea. Use of the slow-to-degrade DOC pool during the intermonsoon could temporarily render the Arabian Sea net-heterotrophic and a source of CO₂ to the atmosphere. Stored DOC is also suggested to balance the observed deficit between mesopelagic carbon demand and the sinking particulate organic carbon supply. Knowledge of the significance of bacteria in carbon storage and cycling in the Arabian Sea is needed to understand the response of the ocean’s biogeochemical state to strong physical forcing and climate change.     

东山沿岸海域春秋季溶解态铜,镉的分布特征

１９９０年５月东山沿岸海域溶解态Ｃｕ，Ｃｄ的深度范围分别为０．２５－１．７３和０．００８－０．０６７μｇ／ｄｍ＾３，１１月的分别为０．４１－２．０３和０．０１４－０．２６３μｇ／ｄｍ＾３。Ｃｕ，Ｃｄ含量分布５月和１１月具有明显不同的特征，这除了与春、秋季不同水系消长的影响有关外，还与陆源输入、生物影响有关。，     

Dissolved Organic Matter in Oceanic Waters

The amount of information on oceanic dissolved organic matter (DOM) has increased dramatically in the last decade thanks to the advances in chemical characterization. This information has supported the development of some novel and important ideas for DOM dynamics in the ocean. Consequently, we have a better understanding of the importance of DOM in oceanic biogeochemical cycles. Here we review studies published mainly during 1995–2001, synthesize them and discuss unsolved problems and future challenges. The measurement, distribution and turnover of dissolved organic carbon (DOC) are presented as the bulk dynamics of the oceanic DOM. The size spectrum, elemental composition, and chemical compositions at molecular and functional group levels are described. The mechanisms proposed for the survival of biomolecules in DOM are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

柘林湾水体溶解氧的分布特征及其与营养盐的关系

根据2001年7月～2002年7月间对柘林湾进行的溶解氧和营养盐含量的调查数据,探讨柘林湾海域溶解氧的时空分布规律及其与营养盐之间的相关关系.结果表明柘林湾的溶解氧含量年均值为5.88mg/dm^3,呈河口、湾外高,湾内低的平面分布规律.回归分析表明,柘林湾溶解氧含量与NO3-N含量呈显著的正相关关系,与PO4-P、NH3-N含量呈显著的负相关关系.大规模的养殖生产是影响柘林湾水体DO含量的一个重要因素.     

Limited nutritional benefit to the seagrass Halophila ovalis, in culture, following sediment organic matter enrichment

Essential nutrients for seagrass growth may be derived from benthic decomposition of organic matter. To test this idea, cores of Halophila ovalis (seagrass-vegetated) and unvegetated sediment (control) were amended with either particulate organic matter (POM) or dissolved organic matter (DOM) to test whether a positive feed-back loop exists, where increased organic matter results in increased seagrass nutrients. POM was added in the form of seagrass wrack (0, 1, 5, 12 g core⁻¹) and DOM was added with sucrose diffusion tubes at the root zone (0, 0.8, 2.4, 5.2 g core⁻¹). Cores were incubated under saturating light conditions (12 h light/12 h dark) at 18 °C, for 4 weeks. Results suggest a complex balance between positive and negative effects of organic matter enrichment. Whilst leaf molar concentrations of N and P of H. ovalis increased (by 15 and 30% respectively), plant growth declined (up to 50% relative to control) for both DOM and POM enrichments. Phosphate was removed from sediment porewater following POM addition and most likely translocated to the leaves. Stressors other than nutrient limitation (e.g. biogeochemical constraints) reduce growth and affect the nutrient dynamics of the seagrass and should be the focus of future work.     

《向阳红九号》调查船的空气微生物

本文对《向阳红九号》调查船做了空气微生物的监测，结果表明：平均全船舱内空气微生物总量、空气真菌含量、空气真菌量占空气微生物总量的百分数分别是３７３０．９ＣＦＵｍ－３，１６８．１ＣＦＵｍ－３和１５．３×１０－２。尚未超过国家对客船规定的卫生标准，但有２１×１０－２的测定结果已超标。两次测定间的差异主要由空气扰动状况所致；层间及舱室间的差异是因人员工作生活习惯等造成的。结果还表明，较好条件的上层乃至全船舱室大有改善环境卫生条件的必要。     

Isotope distribution of dissolved carbonate species in southeastern coastal aquifers of Sicily (Italy)

Concentrations of major ions and the δ¹³C composition of dissolved inorganic carbon in groundwater and submarine groundwater discharges in the area between Siracusa and Ragusa provinces, southeastern Sicily, representing coastal carbonate aquifers, are presented and discussed. Most of groundwater analysed belongs to calcium bicarbonate type, in agreement with the geological nature of carbonate host rocks. Carbonate groundwater acquires, besides the dissolution of carbonate minerals, dissolved carbon (and the relative isotopic composition) from the atmosphere and from soil biological activity. In fact, δ¹³C values and total dissolved inorganic carbon contents show that both these sources contribute to carbon dissolved species in the waters studied. Finally, mixing with seawater in the second main factor of groundwater mineralization Copyright © 2007 John Wiley & Sons, Ltd.     

Impact of anthropogenic activities on the hydrologic characters of the mainstream of the Tarim River in Xinjiang during the past 50 years

Changes in the hydrologic characters of the Tarim River Basin of Xinjiang Province during the past 50 years were studied to identify the key factors responsible for these changes. Observed hydrologic and socio-economic data provided the basis for this study. The impact of human activities on the decrease in the streamflow and changes in total dissolved solids (TDS) in the watercourse and groundwater of the mainstream were analyzed using the Mann–Kendall test, regression and principal component analysis. The results showed that during the past 50 years the streamflow in the headwater streams has increased slightly while the streamflow in the mainstream has decreased significantly. Human activities along the mainstream are the primary reason for the decreased streamflow, with the impact of human activities on the decrease in the streamflow of the mainstream being 65.61, 74.73 and 77.62% in the 1970s, 1980s and 1990s, respectively. The key factor that affected the TDS of the watercourse was the decreasing streamflow, which was caused by anthropological activities. However, the TDS of the groundwater was found to be affected significantly by groundwater depth. The degeneration of ecosystems in the lower reaches of the Tarim River was directly related with anthropogenic activities.