夏季渭河西安段溶解性有机质(DOM)的特征、分布及来源分析

通过紫外吸收光谱,三维荧光光谱结合平行因子分析(EEMs-PARAFAC)方法及主成分分析(PCA),研究了夏季渭河西安段水体中的溶解性有机质(DOM)的组成、来源,及其与水质指标的相关性.在研究区域共检出2种类别5个不同的DOM组分,分别为类腐殖质荧光组分C1、C2、C3、C5和1个类蛋白类荧光组分C4,5个组分具有同源性.对比分析光谱斜率S、SUVA₂₅₄、α355和DOC浓度,上游(S1—S5)和下游(S13—S17)各组分分子量和腐殖化程度接近但来源有所差异,中游(S6—S12、S18—S19)分子量和腐殖化程度最低;研究区域DOM和CDOM浓度值变化基本保持一致.通过三维光谱参数和主成分分析进行DOM源解析,内源贡献率为72.36%,外源贡献率为12.45%,累计方差贡献率为84.81%;污废水排放是组分C1、C4的主要来源,C2、C3、C5则来源于城市景观水体和湿地公园中微生物和浮游动植物的活动产生,TN与外源具有较好的相关性而TP与内源相关性较高.水质指标DO、DOC、COD、TN、TP与DOM组分有较强的相关性.在此基础上建立了多元线性回归方程,一定程度上能够利用荧光组分组成和特征反映渭河夏季的水质状况.     

北京市部分地区降雪中溶解性有机物的光谱性能表征

为了解降雪中溶解性有机物(DOM)的特征,采集了北京市不同地区两场降雪,对降雪样品中的DOM进行了紫外-可见光谱、三维荧光光谱、同步荧光光谱表征.结果表明,不同区域降雪中溶解性有机碳(DOC)浓度变化规律不同,这可能与降雪所在区域的下垫面性质不同有关;降雪样品中DOM的芳香性和分子量较低,含有类色氨酸、类富里酸和类蛋白质类物质,腐殖化程度较低,受生物过程影响较大;同步荧光光谱表明,DOM为类蛋白类物质和芳香性化合物,其中存在苯环和具有共轭系统的多环芳烃,含有少量胡敏酸类物质.研究降雪中DOM光谱性质将有助于进一步研究DOM与共存污染物之间的相互作用,为有效利用降雪提供基础性数据.     

pH对洱海沉积物-上覆水溶解性有机质荧光特征影响

不同pH条件下(pH=2、4、6、8、10、12)培养洱海沉积物,利用三维荧光光谱(3DEEM)技术研究了其溶解性有机质(DOM)在培养前后荧光光谱特征变化.结果表明:①培养前,洱海沉积物DOM类富里酸荧光峰在pH(2—8)发生"红移",pH(8—12)时发生"蓝移",紫外区类富里酸(A峰)荧光强度可见区类富里酸(C峰)荧光强度,类富里酸荧光物质受pH影响不大,这与其结构复杂且不易降解有关.②培养前,洱海沉积物DOM类酪氨酸物质受pH影响较大,可见光区类酪氨酸(B1峰)荧光强度紫外区类酪氨酸(B2峰)荧光强度,这与其结构不稳定、易降解及其酚羟基解离pH范围有关.③培养后,洱海沉积物DOM可见区与紫外区类富里酸荧光强度比培养前分别降低了34.1%、32.2%,可见区与紫外区类酪氨酸荧光强度较培养前升高了57.06%、86.65%,即洱海沉积物DOM在培养后部分类富里酸物质逐渐降解为易被微生物利用的类酪氨酸物质,且在偏碱性(pH=8)环境条件下转化最为明显,沉积物DOM组成结构的转化对湖泊水污染与富营养化具有重要指示意义.     

荧光光谱结合多元统计分析太子河本溪段水体DOM组成及其与水质相关性

激发-发射矩阵荧光光谱法结合多元统计研究溶解性有机物(DOM)在太子河本溪城市段的组分和结构,并揭示其与水质的相关性.沿太子河本溪城市段共设置7个采样点.结果表明,太子河本溪城市段的水质已深受人类活动的影响;基于DOM荧光光谱性质,DOM的组分为类酪氨酸、类色氨酸,类溶解性微生物副产品、类黄腐酸和类腐殖酸物质,其中类蛋白物质在DOM中占主导地位;在工业废水集中排放区域,Fe3+、Mn2+等重金属对类腐殖质荧光产生了猝灭作用,并且该区域的DOM腐殖化程度高于其他区域;太子河本溪城市段水体中DOM组成与结构呈现城市河段及工业废水排放分布特征,DOM主要来源于城市段处理和未处理的工业废水.     

几种原料生物炭溶解性有机质(DOM)的光谱特征研究

溶解性有机质(DOM)在全球碳循环及污染物的迁移转化过程中起着重要作用,而光谱特征能快速识别DOM的主要来源和重要特征。研究针对几种原料(苹果枝、橘子枝、花生壳、水稻秸秆、玉米秸秆)在同一热解温度下制备的生物炭,采用紫外-可见吸收光谱、三维荧光光谱和傅里叶变换红外光谱相结合的方法对其释放的DOM光谱特征进行了研究。结果表明：秸秆类生物炭的溶解性有机碳(DOC)含量显著高于其他3种生物炭;紫外-可见光谱分析表明,5种生物炭DOM的芳香性组分含量均较少,腐殖化程度较低,亲水性组分占主导;三维荧光光谱分析表明,秸秆类生物炭DOM的荧光组分物质含量高于木质类和壳类,且各荧光组分含量占比中可溶性微生物降解产物和类胡敏酸比例最高;傅里叶变化红外光谱表明,5种生物炭DOM光谱特征相似,含有丰富的有机官能团(如羧基、酚羟基等)或半醌自由基等。     

洱海沉积物不同分子量溶解性有机氮空间分布及光谱特征

利用超滤技术对洱海沉积物溶解性有机氮(DON)进行分子量分级,探究了DON各组分空间分布特征,并运用紫外-可见吸收光谱和三维荧光光谱对其结构进行了表征.结果表明,洱海沉积物总DON含量ω(DON)为23.46—61.40 mg·kg-1,平均值为37.19 mg·kg-1,空间分布总体呈现南部>北部>中部的趋势;分子量大于1K Da的大分子组分ω(>1KDa)占ω(DON)的比例为79.1%—93.0%,即洱海沉积物DON是以大分子为主.沉积物DON各组分的芳香性及腐殖化程度较高,芳香环取代基中活性官能团种类较多,且南部芳香性及腐殖化程度最高,北部芳香环取代基种类最多;大分子组分DON含有类富里酸荧光物质,其来源于陆源输入和微生物降解共同作用.由此可见,洱海沉积物DON主要由大分子物质组成,其腐殖化程度较高且含类富里酸荧光物质,而此类DON对藻类的生物有效性较低,这可能是洱海沉积物氮含量较高而上覆水氮浓度较低的原因之一,即沉积物DON分子组成及其结构特征可在一定程度上作为湖泊营养水平的衡量指标.     

沙颍河流域水体中溶解性有机质(DOM)的荧光光谱解析

应用三维荧光光谱技术(EEMS),研究了沙颍河流域水体中溶解性有机质(DOM)的荧光光谱特征,并探讨了沿岸生态系统对水体中DOM的性质及来源的影响.结果表明,沙颍河流域水体DOM均存在类色氨酸、类酪氨酸、可见光区和紫外光区类腐殖质4种荧光峰,其中贾鲁河水样中类蛋白与类腐殖质含量均最高.相关性分析显示,沙颍河流域干流和各支流的A、C峰代表的类腐殖质组分均存在共源性.荧光参数分析显示,沿岸土地利用类型以林业为主的澧河水体的DOM陆源性更强,腐殖化程度相对较高;其余各支流受两岸农田及人为排放的影响,水体具有明显的自生源特征,且新生DOM含量较高.贾鲁河荧光特征显示了其水体受人为干扰比较大.     

消落带夏冬季土壤溶解有机质的组成特征及来源

溶解性有机质(Dissolved organic matter,DOM)普遍存在于土壤、沉积物和水体中,在环境地球化学和全球碳循环中发挥重要作用。消落带独特的"干湿交替"使土壤有不同的季节特征,但有关不同季节土壤DOM的性质、组成及来源差异还未见报道。利用紫外-可见光谱、三维荧光光谱(Excitation-emission matrices,EEMs)与平行因子分析模型(Parallel factor analysis,PARAFAC)相结合的方法,分析了丹江口库区消落带表层土壤DOM在不同季节的组成、结构,并对其来源进行解析。结果表明,不同季节消落带土壤DOM的组成特征存在一定差异。冬季土壤的有色溶解性有机物(Chromophoric dissolved organic matter,CDOM)浓度、土壤DOM的芳香性、缩合度、腐殖化程度、所含疏水性组分都高于夏季土壤,但参与光漂白的活性要低于夏季土壤。荧光指数(FI)、腐殖化指数(HIX)和生物源指数(BIX)表明该区土壤DOM的来源在不同季节都有明显的自生源特征,且腐殖化程度和生物可利用性都不高,并未表现显著差异。该区土壤DOM存在两个主要的荧光峰:紫外光区类富里酸峰、可见光区类富里酸峰和类腐殖酸峰。研究提出消落带淹水期间产生的DOM对水环境有很大影响,以内源为主的库区在水质改善的过程中需加强对内源物质的管控。这些研究结果可为消落带的水体修复和污染物的迁移转化提供科学依据。     

长江重庆段溶解性有机物的荧光特性分析

利用三维荧光光谱(EEMs),并结合平行因子分析(PARAFAC)及主成分分析(PCA),研究了长江重庆段溶解有机物(DOM)的荧光组分特征及其污染来源,并探讨了荧光强度同溶解性有机碳(DOC)及溶解氧(DO)的相关性.结果表明,PARAFAC模型识别出长江重庆段DOM由2类6个荧光组分组成,即类腐殖质荧光组分C1(350/422 nm)、C4(245,305/395 nm)、C5(260,340/420 nm)、C6(260/480 nm)及类蛋白荧光组分C2(275/300 nm)、C3(227,278/329 nm).在DOM来源组成中,陆源的类腐殖质含量占62.56%,类蛋白物质含量占31.31%.类腐殖质组分的荧光强度同DOC的含量存在明显的线性正相关(r=0.73),类蛋白组分的荧光强度同DO的含量呈明显的线性负相关(r=0.80).EEMs-PARAFAC不仅可以表征长江重庆段DOM的光谱特征,示踪长江重庆段的有机污染程度,还可以为三峡库区水体保护提供依据.     

城郊关键带土壤中溶解性有机质的光谱特性及其时空变异

溶解性有机质(DOM)作为地球关键带中物质与能量循环的重要活性组分,其与关键带中诸多重要环境过程有着密切关系.本研究以宁波樟溪流域作为城郊关键带的典型代表区域,采集土壤样品,结合紫外可见光谱(UV-Vis)、三维荧光光谱(3D-EEM)进行特征表征,分析不同类型土壤中DOM的分布特征、影响因素和季节性变化规律.主要结果如下:林地DOC平均含量均大于耕地,其中林地秋季(15.4 mg·L~(-1))林地春季(12.5 mg·L~(-1));耕地秋季(11.9 mg·L~(-1))耕地春季(11.4 mg·L~(-1));DOM结构在紫外可见光谱下表现为耕地DOM芳香化程度(SUVA_(254))、疏水性组分(SUVA_(260))和分子量(S_R)较林地大,其中耕地秋季最为突出;三维荧光光谱结合平行因子分析(PARAFAC)把土壤DOM分为5种组分,主要以富里酸类物质为主(C_1、C_3、C_5),也含有色氨酸、酪氨酸类蛋白质(C_4)和腐殖酸(C_2)等物质,其中耕地春季的腐殖化程度最大,耕地秋季比春季含有较多类蛋白质,林地较耕地含有更多的类蛋白质,林地春秋两季中DOM结构变化不大.     

Evaluating the trophic status of a shallow polluted lake,lake Ioannina,Greece

Lake Ioannina in western Greece is a shallow lake, charged by springs as well as untreated discharges of the nearby urban area. Physicochemical and biological parameters have been evaluated verifying the deterioration of the lake aquatic environment. The water quality and the trophic status of the lake are greatly altered during the last ten years while the total phosphorus critical loading is already at a dangerous state.     

Tracking the metal distribution in the tropical Valencia lake catchment: Soil, rivers and lake

In tropical areas, the relations between soil, rivers, and lakes are poorly understood as regard to the physicochemical transformation that occurs when solid materials are transferred among them. In order to ascertain the natural dynamics of Na, K, Mg, Ca, Al, Fe, Mn, Pb, Zn, Cu, Ni, Cr, and Co, as well as the perturbations by human activity, soils and sediments from a tropical catchment were studied. To accomplish the above mentioned objective, the Valencia Lake catchment was subdivided into three systems, i.e. soils, rivers and lakes. Original data and those previously published by Mogolló;n and Bifano (1994), and Mogolló;n et al. (1995, 1996) were used to establish the numerical relation between the average concentration in the three systems. The percentage labile fraction and metal distribution in different particle size fractions were studied in selected samples. A total of 410 samples was analysed.Lithology and topography are the main factors that differentiate the physicochemical characteristics of soils and sediments. Processes coupled with solid material transport from the upland to lowland area cause the increase of the HNO₃ (1M) extractable metal concentration, and of the percentage labile fraction, metal redistribution towards fine particle fraction. In spite of the tropical climate, the pedogenesis of exposed sediments and the transport along the river courses, have very low influence. Most of the transformations seem to occur during the soils – river transfer of materials. The carbonate precipitation in the lake causes further increase of metal concentration and the percentage labile fraction. The pollutant input increases metal concentration, the percentage labile fraction and the trend of accumulation toward fine particles.     

Adsorption of sulfonamides on lake sediments

Sulfonamides (SAs) are one class of the most widely used antibiotics around the world. Their fate and transport in the aquatic environment is of great concern. In this study, adsorption of four SAs—sulfadiazine (SD), sulfamethoxazole (SMZ), sulfadimethoxine (SDM) and sulfamethazine (SM2)—in single-solute and multi-solute systems on sediments of Dianchi (DC) Lake and Taihu (TH) Lake, China was investigated with batch experiments. In the single-solute adsorption system, the Langmuir model and the dual-mode model described the adsorption process better than the Freundlich model. Model fitness was better on DC sediment than on TH sediment. The order of adsorption capacity approximately followed a decreasing order of SDM>SD>SM2>SMZ on both sediments, which was likely attributed to the distinctly different water solubility of the four SAs. In the multi-solute system, the order of adsorption capacity was SM2>SDM>SD>SMZ, which was probably related to the compound speciation caused by the pH values of the experimental solution. In the multi-solute system, both competitive and cooperative adsorption played important roles in the adsorption of sulfonamides on sediments.     

A 200-year perspective on alternative stable state theory and lake management from a biomanipulated shallow lake

Multiple stressors to a shallow lake ecosystem have the ability to control the relative stability of alternative states (clear, macrophyte-dominated or turbid, algal-dominated). As a consequence, the use of remedial biomanipulations to induce trophic cascades and shift a turbid lake to a clear state is often only a temporary solution. Here we show the instability of short-term manipulations in the shallow Lake Christina (Minnesota, USA) is governed by the long-term state following a regime shift in the lake. During the modern, managed period of the lake, three top-down manipulations (fish kills) were undertaken inducing temporary (5-10 years) unstable clear-water states. Paleoecological remains of diatoms, along with proxies of primary production (total chlorophyll a and total organic carbon accumulation rate) and trophic state (total P) from sediment records clearly show a single regime shift in the lake during the early 1950s; following this shift, the functioning of the lake ecosystem is dominated by a persistent turbid state. We find that multiple stressors contributed to the regime shift. First, the lake began to eutrophy (from agricultural land use and/or increased waterfowl populations), leading to a dramatic increase in primary production. Soon after, the construction of a dam in 1936 effectively doubled the depth of the lake, compounded by increases in regional humidity; this resulted in an increase in planktivorous and benthivorous fish reducing phytoplankton grazers. These factors further conspired to increase the stability of a turbid regime during the modern managed period, such that switches to a clear-water state were inherently unstable and the lake consistently returned to a turbid state. We conclude that while top-down manipulations have had measurable impacts on the lake state, they have not been effective in providing a return to an ecosystem similar to the stable historical period. Our work offers an example of a well-studied ecosystem forced by multiple stressors into a new long-term managed period, where manipulated clear-water states are temporary, managed features.     

湖泊沉积物对磷酸盐的负吸附研究

分别在高、低两种磷酸盐质量浓度下，研究了6个湖泊沉积物对磷酸盐的负吸附。结果表明，(1)污染严重的湖泊沉积物不仅在上覆水体水质好转时，可能向上覆水体释放磷，即使上覆水体水质没有好转，在一定条件也可能释放；而较为清洁的湖泊沉积物，在上覆水体水质下降时，可能从上覆水体中吸附磷。在水质好转情况下，也可能向上覆水体中释放磷。(2)湖泊沉积物吸附磷酸盐过程中存在负吸附，吸附研究中使用较高质量浓度磷溶液是负吸附现象被掩盖的原因；在吸附研究中不仅要重视负吸附，而且初始磷酸盐质量浓度不能太高。(3)沉积物对磷酸盐的吸附／解吸平衡质量浓度与其有机质、CEC、总氮、总磷以及各形态磷含量均有显著的正相关关系，相比而言。与总磷以及各形态磷含量的相关性最高。污染较为严重的沉积物对磷酸盐的吸附／解吸平衡质量浓度也较高。     

Stochastic gravity models for modeling lake invasions

Freshwater aquatic systems in North America are being invaded by many different species, ranging from fish, mollusks, cladocerans to various bacteria and viruses. These invasions have serious ecological and economic impacts. Human activities such as recreational boating are an important pathway for dispersal. Gravity models are used to quantify the dispersal effect of human activity. Gravity models currently used in ecology are deterministic. This paper proposes the use of stochastic gravity models in ecology, which provides new capabilities both in model building and in potential model applications. These models allow us to use standard statistical inference tools such as maximum likelihood estimation and model selection based on information criteria. To facilitate prediction, we use only those covariates that are easily available from common data sources and can be forecasted in future. This is important for forecasting the spread of invasive species in geographical and temporal domain. The proposed model is portable, that is it can be used for estimating relative boater traffic and hence relative propagule pressure for the lakes not covered by current boater surveys. This makes our results broadly applicable to various invasion prediction and management models.     

Identification of a dynamic lake model by the group method of data handling: An application to lake ontario

A revised algorithm of the group method of data handling (GMDH) is used to model and identify water quality dynamics in Lake Ontario. The state variables in the model are corrected chlorophyll a, volume-averaged over the top 20 m, and soluble reactive phosphorus in three layers, 0–20 m, 20–40 m and from 40 m to bottom. Inputs are the average quarterly temperatures for each layer and the total phosphorus loadings. Two kinds of model are developed: recursive and iterative; they are used to simulate long-term predictions for three different hypothetical rates of phosphorus loading. Results show that GMDH can be usefully employed to develop lake models with a very low expense of manpower and computer time. This exercise compares well with other large-scale modelling efforts of Lake Ontario, even if necessarily more limited in scope.     

湖泊营养物参照状态建立方法研究

建立生态分区内各类型湖泊营养物的参照状态是营养物基准制定过程中最为核心的内容之一。在系统分析和评价国外确定湖泊营养物参照状态的若干种方法,包括参照湖泊法、湖泊群体分布法、三分法、回归分析等几种统计学方法以及模型推断和古湖沼学重建方法后,文章根据总磷（total phosphorus,TP）、总氮（total nitrogen,TN）、叶绿素a（chlorophyll a,Chl-a）和塞氏透明度（Secci depth）等四项指标的历史监测数据,应用若干统计学方法建立了巢湖的营养物基准参照状态。通过互相之间的比较分析以及长江中下游湖区古湖沼学重建数据的验证,推荐采用湖泊群体分布法5％点位对应的值作为巢湖营养物基准的参照状态。因此,巢湖营养物参照状态阈值范围为总磷0．023～0．27mg·L^-1,总氮O．62～0．63mg·L^-1,叶绿素aO．65～0．67mg·m^-1,塞氏透明度0．65-0．72m。     

A review of recent developments in lake modelling

This paper reviews the lake models published the last five years, mainly in Ecological Modelling. The review shows that structurally dynamic modelling and coupling between hydrodynamic and ecological models are applied increasingly. A number of processes that have not been included in lake models before have been proposed. It has been shown that these additional processes in specific case studies are significant, for instance the competition between phytoplankton and macrophytes or cyanobacteria growth and growth of mussels. It is recommended to study these models for the development of models for case studies where these processes are relevant.