Modeling the role of macroalgae in a shallow sub-estuary of Narragansett Bay, RI (USA)

Proliferation of macroalgal mats is a frequent consequence of nutrient-driven eutrophication in shallow, photic coastal marine ecosystems. These macroalgae have the potential to significantly modify water quality, plankton productivity, nutrient cycling, and dissolved oxygen dynamics. We developed a model for Ulva lactuca and Gracilaria tikvahiae in Greenwich Bay, RI (USA), a shallow sub-estuary of Narragansett Bay, as part of a larger estuarine ecosystem model. The model predicts the biomass of both species in units of carbon, nitrogen, and phosphorus as a function of primary production, respiration, grazing, decay, and physical exchange, with particular attention to the effects of biomass layering on light attenuation and suppression of metabolic rates. The model successfully reproduced the magnitude and seasonal cycle of area-weighted and peak biomass in Greenwich Bay along with tissue C:N ratios, and highlighted the importance of grazing and inclusion of self-limitation primarily in the form of self-shading to overcome an order of magnitude difference in rates of production and respiration. Inclusion of luxury nutrient uptake demonstrated the importance of internal nutrient storage in fueling production when nutrients are limiting. Macroalgae were predicted to contribute a small fraction of total system primary production and their removal had little effect on predicted water quality. Despite a lack of data for calibration and a fair amount of sensitivity to individual parameter values, which highlights the need for further autecological studies to constrain formulations, the model successfully predicted macroalgal biomass dynamics and their role in ecosystem functioning. Our formulations should be exportable to other temperate systems where macroalgae occur in abundance.     

Estimating the critical phosphorus loading of shallow lakes with the ecosystem model PCLake: Sensitivity, calibration and uncertainty

There is a vast body of knowledge that eutrophication of lakes may cause algal blooms. Among lakes, shallow lakes are peculiar systems in that they typically can be in one of two contrasting (equilibrium) states that are self-stabilizing: a ‘clear’ state with submerged macrophytes or a ‘turbid’ state dominated by phytoplankton. Eutrophication may cause a switch from the clear to the turbid state, if the P loading exceeds a critical value. The ecological processes governing this switch are covered by the ecosystem model PCLake, a dynamic model of nutrient cycling and the biota in shallow lakes. Here we present an extensive analysis of the model, using a three-step procedure. (1) A sensitivity analysis revealed the key parameters for the model output. (2) These parameters were calibrated on the combined data on total phosphorus, chlorophyll-a, macrophytes cover and Secchi depth in over 40 lakes. This was done by a Bayesian procedure, giving a weight to each parameter setting based on its likelihood. (3) These weights were used for an uncertainty analysis, applied to the switchpoints (critical phosphorus loading levels) calculated by the model. The model was most sensitive to changes in water depth, P and N loading, retention time and lake size as external input factors, and to zooplankton growth rate, settling rates and maximum growth rates of phytoplankton and macrophytes as process parameters. The results for the ‘best run’ showed an acceptable agreement between model and data and classified nearly all lakes to which the model was applied correctly as either ‘clear’ (macrophyte-dominated) or ‘turbid’ (phytoplankton-dominated). The critical loading levels for a standard lake showed about a factor two uncertainty due to the variation in the posterior parameter distribution. This study calculates in one coherent analysis uncertainties in critical phosphorus loading, a parameter that is of great importance to water quality managers.     

Mathematical problem definition for ecological restoration planning

Ecological restoration is an increasingly important tool for managing and improving highly degraded or altered environments. Faced with a large number of sites or ecosystems to restore, and a diverse array of restoration approaches, investments in ecological restoration must be prioritized. Nevertheless, there are relatively few examples of the systematic prioritization of restoration actions. The development of a general theory for ecological restoration that is sufficiently sophisticated and robust to account for the inherent complexity of restoration planning, and yet is flexible and adaptable to ensure applicability to a diverse array of restoration problems is needed. In this paper we draw on principles from systematic conservation planning to explicitly formulate the ‘restoration prioritization problem’. We develop a generalized theory for static and dynamic restoration planning problems, and illustrate how the basic problem formulation can be expanded to allow for many factors characteristic of restoration problems, including spatial dependencies, the possibility of restoration failure, and the choice of multiple restoration techniques. We illustrate the applicability of our generic problem definition by applying it to a case study - restoration prioritization on The Irvine Ranch Natural Landmark in Southern California. Through this case study we illustrate how the definition of the general restoration problem can be extended to account for the specific constraints and considerations of an on-the-ground restoration problem.     

广西地下水污染现状与防治对策研究

基于广西地下水基本现状,分析广西地下水污染成因及地下水污染防治中存在的不足,提出建立健全地下水污染防治法律法规;完善地下水监测站网规划,建立地下水监测信息系统;加大宣传力度,提高公众环境保护意识;从整体规划广西地下水的使用与治理;加大资金投入,重视地下水科学研究5点污染防治建议,为今后广西地下水开发利用及污染防治研究提供一定的理论参考。     

全氟化合物污染现状及风险评估的研究进展

全氟化合物(polyfluorinated compounds,PFCs)是近年来受到广泛关注的一类新型持久性有机污染物。PFCs因具有优良的化学稳定性、耐热性以及高表面活性,而被广泛应用于生活消费和工业生产等领域。PFCs具有难降解、生物富集和长距离迁移等特点,已在大气、土壤和水体等环境介质及生物体中检出。在生态环境中,PFCs能够通过食物链不断传递放大,其具有的多种毒性效应已对生态系统和人类造成了一定的威胁。本文主要综述了PFCs在各类环境介质的污染现状、生物的毒性效应、人类摄入健康风险评估以及PFCs的降解研究,以期为未来PFCs的研究提供参考。     

水稻中硅元素的分布及存在状态

利用UV-Vis分光光度计、X线分析显微镜及扫描电子显微镜(Scanning electron microscope,SEM)对水稻不同器官中硅元素的含量、分布及存在状态进行观察和分析,研究水稻中硅酸的化学性质,为水稻硅元素的综合利用提供科学依据.结果表明:水稻以可溶性原硅酸的形式吸收土壤中的硅酸,同样以可溶性原硅酸的形式输送到各器官中.不同的生长期,水稻导管液内的可溶性原硅酸的含量不同,成熟期最高可达到912 mg/L(以SiO2表示).通过比较导管汁液和土壤溶液的硅酸浓度可知,水稻选择性地吸收和浓缩硅酸,最高浓缩率可达85倍.X线分析显微镜观察发现,硅酸普遍存在于水稻各器官中,越是坚硬的部位硅酸分布得越多.SEM图像表明,沉积在水稻各器官中的硅胶体具有一定的形状且不溶于强酸.对水稻干燥组分中硅酸含量的分析结果表明,稻壳中硅酸含量最高,达到13.3%,是生产硅单质及碳化硅材料的最有效的资源之一.     

柴油机排气微粒组分及尺寸分布研究现状分析

对柴油机微粒的研究是控制微粒排放的前提,也是满足未来排放法规的需要。从柴油机微粒形成的机理及其危害出发,介绍了柴油机微粒的检测方法,对柴油机微粒的组成及尺寸分布研究现状进行分析。对柴油机微粒的控制和净化技术的研究有一定的指导作用。     

结合态雌激素的检测方法及污染现状

结合态雌激素是天然雌激素物质的一种重要赋存形态,在环境中可水解为自由态,产生内分泌干扰效应,因此具有潜在的环境风险,并且会影响天然雌激素污染调查和毒性评估的准确性.本文详细探讨了结合态雌激素特定的化学结构对其检测、转化及环境风险等方面的影响,对比分析了目前常用的几类检测方法的优缺点,并初步总结了其在污水处理设施和环境水体中的污染浓度及归趋,以期为我国开展相关研究工作提供参考.     

Trophic state,ecosystem efficiency and biodiversity of transitional aquatic ecosystems: analysis of environmental quality based on different benthic indicators

Estuaries and coastal lagoons are characterized by a strong spatial and temporal variability of physicochemical characteristics and productivity patterns. In these environments, the magnitude and direction of the ecological responses to inorganic nutrient increase (i.e. eutrophication) are difficult to predict. In the framework of the project, New Indicators of Trophic state and environmental quality of marine coastal ecosystems and transitional environments (NITIDA), we analysed benthic indicators of trophic state, ecosystem efficiency, and environmental quality in four different transitional environments. The trophic state of the sediments was assessed in terms of quantity and bioavailability of sediment organic C pools; ecosystem efficiency was determined in terms of the prokaryote efficiency in exploiting enzymatycally degraded organic C; environmental quality was determined in terms of meiofaunal diversity. Here, we provide a synopsis of the results obtained and a meta-analysis of the scores assessments obtained using the different ecological indicators of environmental quality and demonstrate that trophic state, ecosystem efficiency, and biodiversity in transitional ecosystems are closely linked. We conclude that the assessment of the environmental quality of transitional ecosystems should be based upon a battery of trophic state indicators and ‘sensors’ of ecosystem functioning, efficiency, and quality.     

燕山典型流域两种造林树种生态系统碳储量及固碳潜力研究

选择燕山典型流域6个林龄序列的小叶杨（Populus simonii）和5个林龄序列的山杏（Prunus sibirica）主要造林树种为研究对象,利用时间替代空间样地测量法量化退牧还林后生物量碳储量、凋落物碳储量和土壤碳储量及生态系统碳储量的变化规律,同时以各组成碳库-林龄序列中的最大碳储量之和作为生态系统饱和碳储量,以未退牧的天然草地生态系统碳储量作为初始植被类型的碳储量,分析总结了退牧还林对生态系统碳储量和碳循环的影响。结果表明,退牧还林后生态系统的生物量碳储量、凋落物碳储量基本随退牧年限的增加而增加,土壤碳储量随退牧年限的增加呈现先减小后增加的趋势。在没有人为干扰的情况下,9、15、18、22及29 a生小叶杨林的生态系统碳储量分别为7147.45、7461.67、7509.895、8468.375及8247.85 g·m^-2,9、15、18、22及26 a生山杏林的生态系统碳储量分别为6695.44、6700.82、8011.86、8001.92及7981.92 g·m^-2;9、15、18、22、29及36 a生小叶杨林的生态系统固碳潜力分别为757.08、1071.3、1119.53、2078.01、1857.48及1312.21 g·m^-2,9、15、18、22及26 a生山杏林的生态系统固碳潜力分别为310.45、1621.49、1611.55、1591.55及757.08 g·m^-2。长期来看,研究区退牧还林对提高生态系统碳汇能力是可观的、积极的。研究结果对提高造林对碳汇影响的估测能力提供数据支持,也为政府参与国际全球气候变化的谈判提供一个很好的案例研究和科学根据。