Optical properties of low molecular weight and colloidal organic matter: Application of the ultrafiltration permeation model to DOM absorption and fluorescence

Cross-flow ultrafiltration (CFF) is often used to obtain separation and concentration of colloids from bulk natural water samples. Application of the ultrafiltration permeation model allows the quantitative determination of the low molecular weight material (LMW, < 1 kDa) and colloids in bulk dissolved organic matter (DOM) from measurements of time series permeate samples obtained from CFF. Detailed analysis of a Yukon River water sample shows that DOM absorption coefficient and fluorescence follow the permeation model and that the complex spectral optical properties of LMW DOM can be reconstructed from CFF data. A combination of measured and modeled data indicates that the LMW contribution to bulk DOM optical properties obtained from CFF can be grossly underestimated by the use of a low concentration factor (CF, the ratio of initial sample volume to retentate volume). Even at a relatively high CF of 19, optical properties of LMW DOM calculated from measurements of the retentate or integrated permeate would underestimate true values by 5–36%. In the Yukon River sample, LMW dissolved organic carbon represented 26% of the bulk concentration, but only 3–14% of the colored DOM was in the LMW fraction while 31–33% of bulk DOM florescence was due to LMW DOM. The contrasting optical properties of LMW and colloidal DOM support the concept that analysis of bulk DOM absorption and fluorescence properties reveals information about DOM molecular weight.     

福建近海主要经济渔业生物营养级和有机碳含量研究

本文研究了福建近海52种鱼类、6种虾类、4种蟹类、1种虾蛄和4种头足类的食性和营养级及其有机碳含量。结果表明：营养级以鱼类最高，为2．1～3．7级，平均2．65级；头足类为2．04～2．88级，平均2．60级；蟹类2．38～2．73级，平均2．58级；虾类最低，为1．64～2．21级，平均1．96级．干样有机碳含量百分率也以鱼类最高，为33．0％～76．2％(m／m)，平均46．25％(m／m)；头足类为27．80％～46．16％(m／m),平均40．24％(m／m)；虾类为30．60％～38．40％(m／m),平均34．90％(m/m)；蟹类最低,为25．00％～30．78％(m/m)，平均28．24％(m／m),鲜样有机碳含量百分率还是以鱼类最高,为4．80％～29．55％(m／m),平均13．75％(m／m)；蟹类为8．90％～12．68％(m／m),平均10．74％(m/m)；虾类为6．97％～11．53％(m/m)，平均9．55％(m/m)；头足类最低仅为7．38％～8．52％(m／m),平均7．95％(m/m),干样有机碳含量百分率和鲜样有机碳含量百分率与营养级均成正相关，但前者的相关性高于后者。     

REE distribution in water-sediment interface system at deep ocean floor

ＲＥＥｄｉｓｔｒｉｂｕｔｉｏｎｉｎｗａｔｅｒ－ｓｅｄｉｍｅｎｔｉｎｔｅｒｆａｃｅｓｙｓｔｅｍａｔｄｅｅｐｏｃｅａｎｆｌｏｏｒ￥ＺｈａｎｇＬｉｊｉｅ；ＬｉｕＪｉｈｕａａｎｄＹａｏＤｅ（ＲｅｃｅｉｖｅｄＦｅｂｒｕａｒｙ１，１９９４；ａｃｃｅｐｔｅｄＭａｙ...     

胶州湾海水中颗粒有机碳含量的分布与变化

本文报道了胶州湾表层海水及C_3和D_3站中层和底层水中的颗粒有机碳(POC)的分布与变化规律。结果表明,胶州湾POC年平均浓度为155～410μg/L;平面分布有明显的规律性,近岸和河口一带的含量较高,湾中部较低,湾口诸站为最低;垂直分布有个别数值偏高或偏低现象,但没有明显的规律;季节变化较明显,初春较高,秋季较低。     

珠江口水域化学耗氧量、溶解氧、无机磷与有机磷的三维水质数学模拟

珠江沿岸城市排污量大,对污染源治理能力十分有限,大量污染物通过河流或直接排放到珠江口,河口区半封闭的地形及潮水顶托使得污染物不易输送出外海,致使珠江口水质恶化,原有海洋生态环境遭到破坏,反过来制约了经济的发展.     

网箱养鱼诱发有机物污染的生物监测

介绍三种通过底栖动物群落结构的变化对有机物污染监测和评价的方法,并分别对澳大利亚塔斯马尼亚州Nubeena鳟鱼养殖场内由高密度网箱养鱼诱发的有机物污染进行了检测。结果表明:距网箱垂线0m处为严重污染区域,10m处为中度污染区域,30m为过渡类型,其有机物对该处底栖生物仍具有害影响,60m处为轻度有机物富集区,但该处有机物对底栖生物的总效应是有益的,60m以外为正常区域。本文还对三种方法的适用性进行了讨论。     

思林水电站通航建筑物高边坡稳定分析和评价

应用ANSYS结构分析软件,模拟了思林水电站通航建筑物高边坡的地形、地质条件以及开挖的过程,建立边坡开挖的有限元计算分析模型,分析边坡在自然状态、分级开挖以及锚杆支护加固等工况下的应力、变形及其整体稳定性.定义单元的局部安全系数,得到了边坡开挖加固后稳定安全系数的分布.根据计算成果,指出现设计加固措施可以保证边坡稳定,无需增加其他工程措施.