Spatial and temporal variations in pH and total alkalinity at the beginning of the rainy season in the Changjiang Estuary, China

The results of field observation carried out in May 2003 were used to examine pH and total alkalinity behaviors in the Changjiang Estuary. It was showed that pH and total alkalinity took on clear spatial variations in values with the minima in the low salinity region. Like salinity, transect distributions of pH and total alkalinity （TA） in a downriver direction had a sharp gradient each. These gradients appeared in such a sequence that the TA gradient was earlier than salinity and pH gradients, and the salinity gradient was earlier than the pH gradient. These distribution characteristics seemed to be strongly influenced by the mixing process of freshwater and seawater, for both pH and total alkalinity had significant linear relationships with salinity and temperature. For pH, phytoplankton activities also had a significant impact upon its spatial distribution. During a period of 48 h, pH and total alkalinity changed within wide ranges for every layer of the two anchor stations, namely, Stas 13 and 20, which were located at the mixed water mass and seawater mass, respectively. For both Stas 13 and 20, pH and TA fluctuation of every layer could be very wide during a 4 h period. As a whole, the data of the two anchor stations showed that neither variations in salinity and temperature nor phytoplankton activities were the main factors strongly influencing the total alkalinity temporal variability on a small time scale. The data of Sta. 20 implied that both salinity variation and phytoplankton activities had a significant influence on pH temporal variability, but the same conclusion could not be drawn from the data of Sta. 13.     

Flux of low salinity water from Aniva Bay (Sakhalin Island) to the southern Okhotsk Sea

In this study, we examined the relationship between the low salinity water in the shelf region of the southern Okhotsk Sea which was seasonally sampled (0–200 m), and fluxes of low salinity water from Aniva Bay. To express the source of freshwater mixing in the surface layer, we applied normalized total alkalinity (NTA) and stable isotopes of seawater as chemical tracers. NTA-S diagrams indicate that NTA of low salinity water in the upper 30 m layer just off the Soya Warm Current is clearly higher than in the far offshore region in summer and autumn. Using NTA-S regression lines, we could deduce that the low salinity and high NTA water in the upper layer originates from Aniva Bay. For convenience, we defined this water as the Aniva Surface Water (ASW) with values S < 32, NTA > 2450 μmol kg⁻¹. Formation and transport processes of ASW are discussed using historical data. The interaction between the maximum core of high NTA water on the bottom slope of eastern Aniva Bay and an anticyclonic eddy at the mouth of Aniva Bay are concluded to control ASW formation. Upwelling of the Cold Water Belt water at the tip of Cape Krillion is considered to cause ASW outflow from Aniva Bay.     

Removal of K^＋, Na^＋, Ca^2＋, and M^g2＋ from saline-alkaline water using the microalga Scenedesmus obliquus

The capability ofScenedesmus obliquus to remove cations （K^＋, Na^＋, Ca^2＋, Mg^2＋） from saline- alkaline water was investigated at different salinities （0, 5, 10, 15, 20, 25） and carbonate alkalinities （0, 5, 10, 15, 20, 25, 30, 35 mmol/L）. K^＋, Na^＋, Ca^2＋, and Mg^2＋ in saline-alkaline water were efficiently removed by S. obliquus. The maximum removal of the cations （29.37 mg for K^＋, 185.85 mg for Na^＋, 23.07 mg for Ca^2＋, 66.14 mg for Mg^2＋） occurred at salinity 25. The maximum removal of K^＋ （2.28 mg）, Na＋ （6.62 mg）, Ca^2＋ （1.01 mg）, and Mg2＋ （0.62 mg） occurred at carbonate alkalinities of 25 mmol/L for K＊, 35 mmol/L for Na＋, 20 mmol/L for Ca2＋, and 25 mmol/L for Mf＋, respectively. Under a salinity stress, the concentration of Na＇ in S. obliquus increased significantly, while that of K~ decreased significantly. The concentrations of Ca^2＋ and Mg2＋ decreased as well. The ratios of K＋/Na~, Ca2＋/Na^＋, and Mg^2＋/Na^＋ were significantly lower in all salinity treatments than those of the control. Under alkaline stress, the concentrations of Nan and K＋ in S. obliquus decreased significantly and the ratios of K^＋/Na^＋, Ca2＋/Na^＋, and Mg^2＋/Na^＋ were significantly higher in all treatments than in the control. Moreover, the concentrations of Ca2＋ and Mg2＋ in S. obliquus at alkalinities of 5-10 mmol/L were significantly higher than those of the other treatments. The removal of Na＋ by S. obliquus mainly occurs through biosorption, and Mg^2＋ and Ca^2 ＋ were removed through both biosorption and bioaccumulation.     

鲢鱼幼鱼对盐、碱耐受性的研究

利用盐碱地区氯化物型地下水进行了鲢鱼幼鱼（Ｌ＝５．４～８．２ｃｍ）对盐度（ｐＨ＝８．６０±０．１８）、碱度（ｐＨ＝８．７４±０．３４）及盐碱混合的急性毒性试验。研究结果表明：鲢鱼幼鱼对盐度的２４、４８、７２和９６ｈ的半致死浓度（ＬＣ５０）分别为：１１．２,９．０,８．６和８．２ｇ·Ｌ－１;对碱度的相应ＬＣ５０值分别为５１．４、２７．１、２３．７和１５．７ｍｍｏｌ·Ｌ－１。盐碱混合的正交试验表明盐度和碱度在致毒过程中作用显著;２４ｈＬＣ５０碱度（Ａｌｋ,ｍｍｏｌ·Ｌ－１）及盐度（Ｓ,ｇ·Ｌ－１）的关系为：Ａｌｋ＝３４．１７－１．７８Ｓ。     

新疆博州地区地下水水化学成分特征灰关联分析

依据新疆博州地区20处地下水水样的水质化验数据,应用关联分析与相关分析相结合的分析方法,分析了地下水样中几种成分与总硬度、总碱度、电导率及矿化度4个指标之间的关系。结果表明,总硬度变化主要受Mg2+影响,水中HCO3-含量与总碱度关系密切,电导率主要受SO42-影响,SO42-与Cl-对矿化度有较大影响。通过相关分析,发现它们之间线性相关性较好。     

Chemical oxygen demand of seawater determined with a microwave heating method

This paper investigates a microwave heating method for the determination of chemical oxygen demand (COD) in seawater. The influences of microwave-power, heating time and standard substances on the results are studied. Using the proposed method, we analyzed the glucose standard solution, the coefficient of variation being less than 2%. Compared with the traditional electric stove heating method, the results of F-test and T-test showed that there was no significant difference between the two methods, but the microwave method had slightly higher precision and reproducibility than the electric stove method. With the microwave heating method, several seawater samples from Jiaozhou Bay and the South Yellow Sea were also analyzed. The recovery was between 97.5% and 104.3%. This new method has the advantages of shortening the heating time, improving the working efficiency and having simple operation and therefore can be used to analyze the COD in seawater.     

Tidal variations of some physico-chemical parameters in Blanca Bay,Argentina

Oxygen, alkalinity, nutrients, pH, temperature and salinity were measured through tidal cycles in two points of Blanca Bay. A clear dependence of nutrients, oxygen and alkalinity with salinity and tide conditions was observed in the inner point, being attenuated in the outer one.     

南海东北部之海水碳酸盐现况

为探讨南海的海水碳酸盐现况，本文利用“海研一号”三个航次（第266、287及316航次）的机会，搜集南海东北角的碳酸盐因子，如温度盐度、pH值、总碱度及总二氧化碳等。南海深层水具有西菲律宾海水深约2200m的水团特性，实测结果显示此两水团的碳酸盐因子并没有明显的差异。由滞留时间、无机碳及有机碳分解速率计算结果显示，南海深层水的滞留时间以40a较为合理。     

Manganese cycling in a eutrophic lake — Rates and pathways

The redox processes regulating transport of Mn in the water column of a eutrophic, dimictic lake (Lake Norrviken, Sweden) are interpreted based on a one-dimensional diffusion-reaction model for Mn(II). It is found that rates and rate constants for oxidation and reduction vary greatly with depth and also with time during the season of stratification. Calculated rates show that Mn(II) oxidation and reduction generally occur in narrow depth intervals (25–50 cm). This is in good agreement with measured profiles of particulate Mn (MnO _x ). Maximum oxidation rate constants (assuming first order kinetics) at each date are in the first half of the season <1 d^–1, but then increases to a rather constant value of about 25 d^–1. These high rate constants are indicative of microbiological involvement in the Mn(II) oxidation. This is further evidenced by SEM-EDS analysis showing Mn enriched particles morphologically similar toMetallogenium. Reductive dissolution of Mn oxides occurs mainly in the zone just below the zone of maximum oxidation rate. The release of Mn(II) is accompanied by production of alkalinity and CO₂. The relation between production rates of Mn(II) and alkalinity indicates that Mn oxides act as terminal electron acceptors in the bacterially mediated oxidation of organic matter. However, the Mn²⁺/CO₂ ratio is significantly lower than what is expected from this process. It is suggested that the Mn reduction is coupled to fermentation. Close coexistence of Mn reduction and oxidation at high rates, such as found in the water column of this lake, facilitates rapid and continuous regeneration of reducible Mn oxides. This gives rise to a quantitatively important mechanism of organic matter oxidation in the water column.     

碱度对水热合成纤蛇纹石纳米管的影响研究

为克服天然纤蛇纹石纳米管在量子组装应用上存在的不易提纯、易被伴生矿物堵塞、管径不均等缺点,以活性MgO和纳米SiO2为原料,采用水热法在不同碱度下合成了系列纤蛇纹石样品.时合成样品的X射线衍射(XRD)、傅立叶红外光谱(FTIR)以及扫描电镜(SEM)分析表明,在200℃.pH值大于13的条件下反应60 h以上能够合成结晶度比较完善的纤蛇纹石;碱度的提高有利于纤蛇纹石氢氧镁石层和硅氧四面体层的生长,并促使两者结合更为紧密,晶胞参数b0值增大,结构层更易卷曲,纤蛇纹石的纤维管状结构更加完善,结晶度提高,纤维的晶体轮廓更加清晰,直径更为均一,长度增加;最后确认在200℃.pH 13.8,反应60 h条件下合成纤蛇纹石纳米管的直径约50 nm.长度多在600nm以上,长度上优于前人的合成.