2020—2021年西安市大气PM2.5中水溶性离子变化特征

用离子色谱法对181份PM_2.5有效样品中NO^-₃、SO₄^2-、NH⁺₄、Cl^-和F^-等5种水溶性离子进行检测分析。结果表明,西安市PM_2.5的年均浓度为(71.04±51.80)μg·m^-3,季节变化特征表现为：冬季>春季>秋季>夏季。五种水溶性离子的年均浓度为(28.24±31.79)μg·m^-3,季节变化特征表现为：冬季>春季>秋季>夏季。各水溶性离子的年均浓度由大到小依次为：NO^-₃>SO₄^2->NH⁺₄>Cl^->F^-。NO^-₃在冬、春、秋三季...     

河道藻源胞内有机质光化学-生物降解机制

藻细胞破裂后会向水体释放大量的胞内有机质(intracellular dissolved organic matter, I-DOM)。I-DOM在河道中将经历复杂的光降解和生物降解过程,影响其在河道中的迁移转化和环境效应。为了探明光照和微生物对I-DOM的降解机制,开展了光降解、生物降解和光-生物降解实验。结果表明,I-DOM经7 d光降解和生物降解后,溶解性有机碳(dissolved organic carbon, DOC)的去除率分别为70%和81%;虽然光照1 d能去除38%的DOC,但后续生物降解(光-生物降解)与无光照生物降解对DOC的去除效率一致。进一步的研究表明,生物降解过程中的呼吸商(respiratory quotient, RQ)低于光-生物降解过程,说明相比于生物降解过程,光-生物降解过程中经光照后生物呼吸时所利用I-DOM的性质发生了改变,进而影响了生物呼吸时O₂的消耗和CO₂的产生。生物降解过程中微生物主要利用原始的I-DOM分子;而在光-生物降解过程中,生物降解过程的微生物主要利用经光降解转化后的I-DOM分子。...     

酰胺基两性分子对二硫化钨吸附铀容量的影响机制

含铀废水中铀的回收主要是基于材料与[UO₂(H₂O)5]²⁺中UO₂⁽²⁺)之间的络合,但H₂O的电偶极矩对络合有显著弱化作用。采用酰胺基两性分子N,N-二甲基-9-癸烯酰胺(NADA)氢键作用与[UO₂(H₂O)5]²⁺形成UO₂[(H₂O)x C₁₂H₂₃NO]_n*(x<5,UO₂-Coordination Compound,简称UO₂-CC),选取惰性物质WS2为吸附材料,通过静态吸附试验(不同pH、接触时间、浓度和温度)分别研究其对UO₂²⁺和UO₂-CC的吸附量。动力学拟合结果表明,二者的吸附反应是化学吸附过程,UO_<     

Mass transport model of ions within biofilms under the effect of external field

A mass transport model was developed to predict the transport rate of ions within biofilms, which was experimentally verified using the fluxes of NH4^＋ and Ca^2＋ through the heterotrophic biofilms with the thickness varying from 230 to 1430μm under the effect of external field in the range of-20 V/m to 60 V/m. It is found that the result predicted by the model is in agreement with the experimentally obtained one, with the error less than 5 percent for the thin biofilms. The error increases with the increase of the biofilm thickness. The transport rate of ions caused by electric migration is affected by the charges, field strength, and biofilm thickness and so on.     

Selective extraction and separation of Fe, Mn oxides and organic materials in river surficial sediments

In order to investigate the adsorption mechanism of trace metals to surficial sediments （SSs）, a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials （OMs） in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH .HCl （0.1 mol/L） ＋ HNO3 （0.1 mol/L）, （NH4）2C2O4 （0.2 mol/L） ＋ H2C2O4 （pH 3.0）, and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09%--3.36% for the hydroxylamine hydrochloride treatment, 80.63%- 101.09% for the oxalate solution extraction, and 94.76%-102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation ofFe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.     

新疆吉木乃诸河水体氢氧同位素和水化学特征

利用2018年6月和11月在新疆吉木乃诸河流域采集的河水、冰雪融水和降水样品,对流域水体的水化学成分和氢氧稳定同位素(D,~(18)O)组成的时间和空间特征进行了系统研究.结果表明,吉木乃诸河在丰水期和枯水期阳离子均以Ca~(2+)为主,阴离子以HCO~-_3为主,其次分别为Na~+和SO_4~(2-).在空间上,Na~+、Mg~(2+)、SO_4~(2-)、Cl~-随着海拔的降低呈增加趋势.通过Piper图可以判断出,吉木乃诸河水化学类型为HCO_3-Ca型.利用Gibbs图可知流域内主要离子组成与各类岩石的风化作用有关,大气降水和蒸发作用的影响相对较小.结合当地的水文地质情况,运用离子含量比值法,可以发现离子主要来源于流域内碳酸盐风化和含硫矿物的氧化.丰水期吉木乃诸河地表水中δ~(18)O和δD较枯水期高,冰川融水的同位素值没有明显的季节变化,降水中的同位素值季节变化较大,其区域大气降水线方程为δD=7.5δ~(18)O+5.4 (R~2=0.99).吉木乃诸河河水中稳定同位素与海拔呈现正相关关系,主要原因是蒸发作用的增加,地表水同位素值偏负.该区域地表径流与冰川融水密切相关,冰川融水对该流域水资源的补给贡献较大.