超高效液相色谱-电喷雾串联四极杆质谱结合内标物测定水体中微囊藻毒素

本文建立了超高效液相色谱-电喷雾串联四极杆质谱(UPLC-MS/MS)测定水体中MC-RR和MC-LR的方法,比较了内标的加入对不同水样富集体积下MCs测定准确度的影响.结果表明,以乙腈和水(均含0.1%甲酸)为流动相时,MC-RR和MC-LR在Acquity UPLC BEH C18色谱分离柱(2.1 mm×100 mm i.d.粒径1.7μm,孔径130)于4 min内完全分离.经优化质谱参数,选择m/z 519.8>134.3和995.5>134.6分别为MCRR、MC-LR质谱检测的定量离子对.方法学验证表明,在所设定的色谱、质谱参数条件下,UPLC-MS/MS对MC-RR和MC-LR的检出限分别为2.0 ng·L-1和1.0 ng·L-1,定量限分别为为6.0 ng·L-1和3.0 ng·L-1,回收率分别达98.9%—106.5%和98.4%—101.5%.测定太湖梅梁湾水样时,当水体中MCs浓度达到UPLC-MS/MS方法定量限20倍时,可通过加入内标物亮氨酸脑啡肽,实现快速(不经过水样富集)且准确(相对标准偏差<5.0%)的MC-RR与MC-LR测定.     

阳离子化壳聚糖改性黏土絮凝去除藻华

壳聚糖改性黏土可以用于治理藻华,但未经改性的壳聚糖具有电荷密度小、溶解度小、pH适用范围较窄以及分子质量较小等缺点,影响了壳聚糖改性黏土除藻的性能。为了优化壳聚糖的絮凝除藻性能,以二甲基二烯丙基氯化铵为阳离子醚化剂,在微波条件下对壳聚糖进行改性合成阳离子型壳聚糖,并研究了阳离子壳聚糖溶解度随pH的变化,以及用它改性后的黏土颗粒的表面电位的变化,并对阳离子壳聚糖改性黏土和壳聚糖改性黏土的絮凝除藻性能进行比较。结果表明,阳离子壳聚糖在酸性和碱性条件下都具有很好的溶解性,经其改性后的黏土颗粒的等电点(pH 10.8)显著高于壳聚糖改性黏土的等电点(pH 9.5)。在絮凝实验中,阳离子壳聚糖改性黏土的最大除藻率达到99%,藻絮体粒径为978μm,即使在pH为10时,仍有87%的去除率。结果表明,阳离子壳聚糖改性黏土的除藻性能明显优于未改性的壳聚糖改性黏土。     

Heavy metals of natural and reclaimed tidal riparian wetlands in south estuary, China

The concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in two plant species (Scirpus tripueter Linn. and Cyperus malaccensis Lam.), water, and soils sampled from the reclaimed tidal riparian wetlands (RTRWs) and the natural riparian wetlands (NRWs) in the Pearl River estuary (PRE), were analyzed to investigate and compare their distribution and accumulation. The results show that the concentrations of the six studied heavy metals in soils exceed the eco-toxic threshold recommended by USEPA. The concentrations of Cd, Cr, and Zn in plants may lead to toxic effects compared to others.The hydraulic conditions and the degree of human disturbances can affect the heavy metal accumulation in RTRWs and NRWs. The heavy metal concentrations in water are higher whereas they are lower in soils of RTRWs Compared with that in the NRWs. The accumulation of heavy metals in the roots of plants is higher in NRWs than those in RTRWs while the opposite result is found for heavy metal accumulation in shoots. Based on the bioaccumulation and translocation factors, the plants in NRWs have the higher capacity to accumulate heavy metals, while higher abilities to transport heavy metals from roots to shoots are observed in RTRWs. Heavy metal contaminations in RTRWs are dominated by anthropogenic sources from both side uplands and river water, whereas in NRWs, the metal accumulations are simultaneously affected by anthropogenic and natural factors.     

气温对长江上游巴塘站年径流的影响分析

为了深入分析气温对长江上游年径流的影响和解释青藏高原冰川融水再冻结现象的物理机制,采用对位置、尺度、形状的广义可加模型(简称GAMLSS)建立控制因素降水、气温、ATD与年径流量之间的关系。在GAMLSS框架下,气温影响因子可以用两种形式表示,一种是直接采用气温,另一种是采取ATD指数(累积气温亏损值)。通过比较不同解释变量组合下的GAMLSS模型,进而研究气温对长江上游巴塘站1960~2012年的年径流影响。结果表明:基于ATD的回归模型,在年径流序列服从对数正态分布假设的条件下拟合效果最优。与气温值相比,ATD指数能更有效地解释长江上游径流变化的特征和冰川产流的物理机制。研究成果对长江上游年径流预报、高原气候下的产流特征分析具有理论意义。