三峡水库香溪河库湾主要营养盐的入库动态

基于香溪河及其主要支流高岚河的5a监测数据,估算三峡水库香溪河库湾氮磷营养盐的入库通量,并分析了氮磷营养盐的浓度及其通量的逐月动态。研究发现,每年大约有1623.49t总氮和331.85t总磷汇入香溪河库湾,其中,香溪河贡献了68.50%的总氮和91.74%的总磷。在这两条河流中,溶解无机氮是氮的主要存在形式;氮通量表现出夏季7月份偏高、春秋季次之、冬季较低的规律;面源污染是氮进入河道的主要途径。磷酸盐是香溪河磷的主要存在形式,而高岚河磷酸盐的含量则较低;香溪河磷通量的月均波动规律不明显,高岚河磷通量的高

武汉市饮用水中浮游藻类的调查

目的了解武汉市饮用水中浮游藻类的污染情况。方法分别于1999-2001年春、夏、秋、冬对武汉市不同水源供水区末梢水和同一地点水箱水进行4次采样,进行藻类形态学检测。结果生活饮用水中浮游藻类有蓝藻门(Cyanophyta)、隐藻门(Cryptohyta)、金藻门(Chrysophyta)、硅藻门(Bacillariophyta)、裸藻门(Euglenophyta)、绿藻门(Chlorophyta)等6个门,56个属、97个种藻类(其中67个鉴定到种,30个鉴定到属)。城市末梢水中浮游藻类检出为89%,饮水水

Preparation and characterization of erbium doped sol-gel silica glasses

Erbium-doped silica glasses were made by sol-gel process. Intensive photoluminescence (PL) spectra from the Er-doped silica glasses at room temperature were measured. A broadband peak at 1535 ma, corresponding to the I-4(13/2)-I-4(15/2) transition, its full width at half-maximum (FWHM) of 10 nm, and a shoulder at 1546 nm in the PL spectra were observed. At lower temperatures, main line of 1535 nm and another line of 1552 Mn instead of 1546 nm appear. So two types of luminescence centers must exist in the samples at different temperature. The intensity of main line does not decrease obviously with increasing temperature. By varying the Er ion concentration in the range of 0.2 wt% - 5wt%, the highest photoluminescence intensity was obtained at 0.2wt% erbium doped concentration. Luminescence intensity decreases with increasing erbium concentration. Cooperative upconversion was used to explain the concentration quenching of luminescence from silica glass with high erbium concentration. Extended X-ray absorption fine structure measurements were carried out. It was found that the majority of the erbium impurities in the glasses have a local structure of eight first neighbor oxygen atoms at a mean distance of 0.255 nm, which is consistent with the typical coordination structure of rare earth ion.