三峡库区澎溪河与磨刀溪电导率等水质特征与水华的关系比较

三峡库区北岸最大一级支流自三峡大坝2003年蓄水以来,频繁暴发水华,而毗邻的一级支流磨刀溪却少有水华暴发.本文以澎溪河和磨刀溪作为研究对象,于2014年春季和夏季三峡库区水华高发期对两条河流同时采样,对比分析两条河流水体水质以及叶绿素a(Chl-a)含量的时空变化,探索澎溪河水华暴发机理.结果表明:澎溪河Chl-a含量较磨刀溪高,澎溪河春季Chl-a最大值为60.5μg·L~(-1),夏季Chl-a最大值仅7.8μg·L~(-1);磨刀溪Chl-a变化趋势与澎溪河相反,磨刀溪春季Chl-a含量为2.92μg·L~(-1),夏季Chl-a达到7.48μg·L~(-1).澎溪河与磨刀溪春季和夏季节水体温度分层,为温跃层+滞温层模式,而没有混合层;两条河流Chl-a含量均位于水深10 m温跃层.澎溪河春季总氮(TN)、总磷(TP)平均值为2.305 mg·L~(-1)和0.053 mg·L~(-1),夏季为1.673 mg·L~(-1)和0.097 mg·L~(-1);磨刀溪春季为1.875 mg·L~(-1)和0.075 mg·L~(-1),夏季为1.79 mg·L~(-1)和0.054 mg·L~(-1).TN、TP水平均超过了国际公认发生富营养化的阈值;水体氮磷含量与Chl-a浓度并无显著相关性,营养盐并不是藻类生物量的限制性因素.然而在水体电导率的规律方面,两条河却存在很大的差异;春季,磨刀溪上游上层水体(0~10 m)电导率只有下游和长江干流的75%,来自长江干流的回水可覆盖至磨刀溪中游(断面MD03),与Chl-a在此处密集保持一致;夏季电导率和回水区分布与春季相似.与磨刀溪不同,澎溪河春季上游电导率为下游和干流的150%,长江干流回水可到PX04与PX05之间,上游高电导率对应着高Chl-a含量;澎溪河电导率与藻类生长分布表现出显著正相关关系,水体中除N、P营养盐外的其它离子对澎溪河水华暴发起重要作用.     

丹江口水库浮游细菌和氮磷循环基因垂直分布特征及其驱动因素

丹江口水库作为南水北调中线工程水源地,不同深度浮游细菌群落组成、 氮磷循环功能及其驱动因素尚未清晰. 选取丹江口水库5个生态点位,采用宏基因组学研究表层、 中层和底层垂直分布浮游细菌群落组成,分析预测氮磷循环功能及其驱动因素. 结果表明,丹江口水库主要由变形菌门、 放线菌门和浮霉菌门等优势种群组成,不同深度来源的浮游细菌群落结构具有显著差异,水温（T）、 氧化还原电位（ORP）、 溶解氧（DO）和Chla是影响浮游细菌群落组成的主要因素. 氮循环功能基因分析表明,主要涉及生物固氮过程、 硝化作用、 反硝化作用和异化硝酸盐还原作用等7个主要途径的gltB、 glnA、 gltD、 gdhA和NRT等39个氮循环功能基因. 磷循环功能基因分析表明,主要涉及有机磷矿化、 无机磷溶解、 调节等6个主要途径的pstS、 ppx-gppA、 glpQ和ppk1等54个磷循环功能基因. 聚类分析表明不同深度是影响氮磷循环功能基因组成和丰度的主要因素,表层和底层氮磷循环功能基因丰度高于中层样品. 奇异球菌属、 嗜氢菌属、 Limnohabitans和棍状杆菌属等是氮磷循环的关键物种. DO、 pH、 T、 总溶解性固体（TDS）、 电导率（EC）和Chla与氮磷循环功能基因显著相关,以上环境因子随丹江口水库深度增加浓度降低或升高,导致浮游细菌氮磷循环功能基因呈明显的垂直分布特征. 通过揭示丹江口水库不同深度浮游细菌群落组成、 氮磷循环功能及其影响因素,可为丹江口浮游细菌生态功能和多样性保护发挥潜在的作用.     

贵州高原红枫湖水库季节性分层的水环境质量响应

为了揭示贵州高原深水水库水体的垂直分层结构及其水环境质量响应特征,于2008年8月~2009年10月对红枫湖水库5个采样点进行了45次采样,对水文、营养盐等湖沼学变量季节动态和分布进行了分析,探讨了季节性水质恶化事件的发生机制.结果表明,红枫湖水库水体呈单循环混合模式,在4~9月形成分层,但没有典型分层湖泊的温跃层变化,这种不显著的分层导致了水化学的分层.叶绿素a、总磷、总氮和氨氮平均值分别为13.6mg/m3,0.063mg/L,1.22mg/L,0.347mg/L;透明度为1.9m.指示该水库处于中-富营养状态.分层期底层溶解氧在0.3~6.9mg/L之间、平均为2.6mg/L,氮磷质量比在8~104之间,表明红枫湖水库是一个底层滞留带季节性缺氧的高氮、磷限制型水库.贵州高原深水水库季节性水质恶化事件与水体分层结构失稳有关,是富营养化水库在气温骤降时发生“翻湖”所导致的结果,也是贵州高原深水水库富营养化的另一种表现形式.     

金盆水库汛期高浊水径流的潜入及热分层水体水质响应

以西安金盆水库为研究对象,在汛期通过对河流区至库区的水温、浊度、DO和营养盐等水质指标进行连续监测,探究降雨径流的潜入规律及热分层水体水质动态响应特性.结果表明:在外界气温变化条件下,水库出现季节性热分层现象.汛期径流的汇入导致下温跃层消亡,热分层稳定性减弱;汛期径流水体携带大量颗粒态营养盐物质和泥沙以异重流形式潜入,其流态从过渡区的底层潜流向主库区间层流转变,潜入初期间层流厚度达20m.降雨早期异重流的潜入导致中下层水体的TN、TP、TOC显著增加,水体平均TN、TP、TOC、浊度最高分别超出平时0.2,2,0.6,16倍,水质呈现短时高污染负荷.底层潜流水体水温较高,大量沉降于沉积物中的颗粒态污染物分解速率加快,內源污染负荷进一步提高,底层水体中TN、TP、TOC浓度高达1.88,0.05,4.6mg/L;汛期可通过分层取水方案和排放高浊水来保障供水安全.     

水体pH值时空变化条件下絮凝除藻剂的pH值优化

研究了由光照、水深等造成的水体pH值变化对絮凝剂除藻效果的影响,并监测絮凝前后不同深度的水体pH值。结果表明:1)当水体pH值无垂向分层,但随光照在8.5~10.5变化时,表层水体终点pH值为5.8~7.9,除藻效率均高于80%,此时中下层水体pH值为5.4~8.0;2)当水体pH值有垂向分层,表层水体终点pH值为7.0~7.3时,除藻效率均高于80%,此时中下层水体pH值为7.0~7.1;3)水池实验中,当表层水体终点pH为6.8时,除藻率高达99.33%,此时中下层水体pH值为7.0~7.1,池水清澈见底。上述结果说明:不论水体pH值是否垂向分层,控制表层水体终点pH值为6.8~7.3时既能有效除藻,也不会使底层水体pH值过低;水体pH值有垂向分层时,絮凝剂的pH值应高于无垂向分层时的情况。     

饮用水源水库铁锰垂直分布规律及原因

经对水温分层型季节性缺氧水库铁、锰污染的研究表明,Fe、Mn分布随着季节变化、水库水温分层而变化,呈现明显的垂直分布规律:高浓度Fe、Mn主要出现在水温分层期水库中、下层,与库底缺氧、pH值下降、基岩溶蚀、沉积物高浓度Fe、Mn释放造成的二次污染等密切相关,从而为自来水厂实施优化分层取水和污染控制提供了依据.     

Behavior of a Small Pulsed River Plume in a Strong Tidal Cross-Flow in the Akashi Strait

We carried out a field study of a small river plume emptying into Osaka Bay near the Akashi Strait in western Japan, to understand the fate of its urban-runoff-laden waters. As the river is weak compared to tidal currents, we find that the behavior of the plume is strongly influenced by phasing between tidal stage and currents (a westward-traveling progressive tidal wave). When the tidal stage rises, sea water floods up the river, and concentrated river effluent cannot be seen in Osaka Bay. During most of the river’s ebb, a topographic eddy transports river effluent towards the energetic Akashi Strait, while strong vertical shear in the tidal flow mixes the effluent with seawater. However, there is a short interval of time during which the direction of tidal flow in the Strait changes direction and the magnitude of the current is weak. At this time, shear is weak enough to allow a stratified plume of concentrated river water to form, and this plume is driven offshore, and into Osaka Bay, by baroclinic circulation. A sewage outfall, which is located very close to the river mouth, is subjected to these same conditions and therefore exhibits similar behavior. Understanding the relation between tidal phase and plume behavior will be useful to Kobe City, as well as other cities in a similar environment, for minimizing the environmental effects of their wastewater and non-point-source runoff.     

Growth, environment and innovation—a model with production vintages and environmentally oriented research

I develop an innovative environmental new growth model driven by researchers striving for monopoly profits. Skilled labour is allocated between production vintages and two forms of research, ordinary and environmentally oriented. The intermediate sector includes fixed costs and decreasing returns, limiting the number of vintages used. I solve for planner's, laissez-faire, and regulator's solutions, and examine welfare implications and the various distortions in the model (monopoly power, knowledge spillovers, business stealing, environmental externalities). A regulator may wish: (i) to encourage environmentally oriented research; (ii) to concentrate production labour on recent (cleaner) vintages; (iii) to switch labour from production to research. An environmental sales tax may under some circumstances achieve all three—such taxes not only give incentives to reduce pollution, but also shift profits from old vintages to new, thus raising incentives to come up with newer (cleaner) vintages. An environmental tax may even lead to an increase in the rate of production growth.     

Renewable resources in an endogenously growing economy: balanced growth and transitional dynamics

We introduce a renewable resource sector into an endogenous growth model of a small economy, deriving the transitional dynamic equilibrium. The model generates a long-run equilibrium in which a resource sector of limited size can coexist with constant ongoing growth elsewhere. The key feature of the model is the allocation of labor between harvesting the resource and its use in the final output sector. This naturally generates the empirically observed negative relationship between resource abundance and growth. We examine both the dynamic and long-run responses of the economy to various shocks pertaining to technological production conditions and resource sector parameters.