Spatiotemporal dynamics in variable population interactions with density-dependent interaction coefficients

In this article, I present a two-patch metapopulation model with locally explicit dynamics to study the effect of spatial heterogeneity and dispersal upon population interactions with variable or conditional outcomes. These are interactions that may be either detrimental or beneficial for each species depending on the balance of the density-dependent costs and benefits involved. The local dynamics respond to density-dependent α-interaction functions that may change sign, thus yielding a diversity of possible local outcomes for the association in terms of type of interaction and in the number of stable solutions. The spatiotemporal model predicts that the fragmentation of space and dispersal between patches may cause further variation in these outcomes. First, the demographic performance of a species in the association is enhanced if migrations cause a proportional increase of individuals of its own species; being so, a victim may become a mutualist or an exploiter, an excluded species may invade, and a good competitor may overcome its own carrying capacity: the ‘enhancement effect of dispersal’; a sort of rescue effect in source-sink dynamics. The underlying mechanisms involve an interplay between density-dependent effects of dispersal per se and the relative local and global average α-interaction functions, which involve costs and benefits at both the local and regional level that may either counteract or reinforce each other; thus, localities and/or populations may change dynamically their sink or source role in the spatial dynamics. A significant insight arises herewith: in the context of variable or conditional interactions the concept of the role of a species does not make strict sense; it becomes a spatiotemporal dynamic quality. Second, regardless of which species disperses, bifurcation of equilibria may occur in those patches that receive the migrating individuals, and annihilation of equilibria in those from where migration leaves; thus, the number of equilibria increases or decreases accordingly.     

Hurricanes and hegemony: A qualitative analysis of micro-level climate change denial discourses

The climate change countermovement and its program of climate change denial have been well documented and studied. However, individual rationales for rejecting climate science remain under-studied. Twitter data related to Hurricane Sandy in 2012 are used to understand why individuals reject the orthodox climate consensus, using a summative content analysis of climate change denial discourses. Three major discourses are discovered: rejecting climate science because climate science is a conspiracy favoring growth of government; opposing renewable energy and energy taxation; and expressing fear of governmental abuse of power. Importantly, each discourse expressed certainty that climate science itself was a wholesale fraud; the denial discourses themselves focused far more on climate politics than on science.     

Copper and cadmium effects on growth and extracellular exudation of the marine toxic dinoflagellate Alexandrium catenella: 3D-fluorescence spectroscopy approach

In this study, metal contamination experiments were conducted to investigate the effects of copper and cadmium on the growth of the marine toxic dinoflagellate Alexandrium catenella and on the production of dissolved organic matter (Dissolved Organic Carbon: DOC; Fluorescent Dissolved Organic Matter: FDOM). This species was exposed to increasing concentrations of Cu²⁺ (9.93 × 10⁻¹⁰–1.00 × 10⁻⁷ M) or Cd²⁺ (1.30 × 10⁻⁸–4.38 × 10⁻⁷ M), to simulate polluted environments. The drastic effects were observed at pCu²⁺ = 7.96 (Cu²⁺: 1.08 × 10⁻⁸ M) and pCd²⁺ = 7.28 (Cd²⁺: 5.19 × 10⁻⁸ M), where cyst formation occurred. Lower levels of Cu²⁺ (pCu²⁺ > 9.00) and Cd²⁺ (pCd²⁺ > 7.28) had no effect on growth. However, when levels of Cu²⁺ and Cd²⁺ were beyond 10⁻⁷ M, the growth was totally inhibited. The DOC released per cell (DOC/Cell) was different depending on the exposure time and the metal contamination, with higher DOC/Cell values in response to Cu²⁺ and Cd²⁺, comparatively to the control. Samples were also analyzed by 3D-fluorescence spectroscopy, using the Parallel Factor Analysis (PARAFAC) algorithm to characterize the FDOM. The PARAFAC analytical treatment revealed four components (C1, C2, C3 and C4) that could be associated with two contributions: one, related to the biological activity; the other, linked to the decomposition of organic matter. The C1 component combined a tryptophan peak and a characteristic humic substances response, and the C2 component was considered as a tryptophan protein fluorophore. The C3 and C4 components were associated to marine organic matter production.     

A Strategy and Methodology for Defensibly Correlating Spilled Oil to Source Candidates

The source of crude oils and petroleum products released into navigable waterways and shipping lanes is not always known. Thus, the defensible identification of spilled crude oils and petroleum products and their correlation to suspected sources is a critical part of many oil spill assessments. Quantitative "fingerprinting" analysis, when evaluated using straightforward statistical and numerical analyses, provides a defensible means to differentiate among qualitatively similar oils and provides the best assessment of the source(s) for spilled oils. Polycyclic aromatic hydrocarbon (PAH) and petroleum biomarker concentration data are a particularly useful quantitative measure that can benefit most oil spill investigations. In this paper the strategy and methodology for correlation analysis that relies upon quantitative gas chromatography/mass spectrometry operated in the selected ion monitoring mode (GC/MS-SIM) is demonstrated in a case study involving 66 candidate sources for a heavy fuel oil spill of unknown origin. The strategy includes identification of 19 chemical indices (out of 45 evaluated) based upon PAH's and biomarkers that were (1) independent of weathering; and (2) precisely measured, both of which are determined by statistical analysis of the data. The 19 chemical indices meeting these criteria are subsequently analysed using principal component analysis (PCA), which helps to determine defensibly the "prime suspects" for the oil spill under investigation. The strategy and methodology described, which combines statistical and numerical analysis of quantitative chemical data, can be adapted and applied to other environmental forensic investigations with the objective of correlating any form of contamination to its suspected sources.     

Critical Review of Environmental Forensic Techniques: Part I

A multitude of forensic techniques are available for age dating and source identification, including aerial photography interpretation, corrosion models, the commercial availability of a compound, chemical associations with discrete type processes, chemical profiling, degradation models and contaminant transport models. These techniques, however, are rarely challenged or discussed in the literature relative to the scrutiny encountered in environmental litigation. When introduced as scientific evidence, the governing assumptions and quality of the data are critically evaluated and frequently successfully challenged. The purpose of this paper is to review five types of forensic techniques and discuss their merits so that a user can decide which technique, or combination of techniques, is most appropriate for developing the technical portion of a case.     

Evaluation of the interaction between soil and antibiotics

The aim of this study was to investigate the occurrence of tetracycline and sulfonamide antibiotics in 13 different soil samples collected from agricultural fields. As well as the antibiotic analysis 18 different physicochemical properties of the soil samples were determined in order to establish a relationship between the recovery rates of antibiotics from the samples and the characteristics of the samples that provide critical information for the reliability of an applied antibiotic analysis method. While the concentrations of tetracyclines were 0.025–0.105 mg kg^?1 sulfonamide antibiotics were not detected in any investigated soil samples. The mean recovery rates of tetracyclines and sulfonamides were 84.57 ± 14.92% and 65.88 ± 8.56%, respectively. Although, the organic carbon contents and cation exchange capacities of the soil samples exhibited a great variation the results of multivariate statistical analysis indicated that the metal content of soils was the major factor significantly influenced the recovery rates of the antibiotics. The sulfonamide recovery rates were positively influenced by the calcium and magnesium amounts in the soil samples, whereas tetracycline recovery rates were markedly diminished by increasing the amount of these polyvalent metals.     

Developments in remote sensing, dynamic modelling and GIS applications for integrated coastal zone management

The International Institute for Aerospace Survey and Earth Sciences (ITC) has a research programme that should result in an integrated environmental coastal zone management system through three subprojects. The programme aims to develop methodologies and tools for assessing coastal zone changes, and for the evaluation of scenarios for coastal zone management, based on a spatio-temporal Geographical Information System (GIS) working platform which integrates remote sensing data, physical-morphodynamic and eco-hydrologic modelling, and a decision support system. The first subproject develops methodologies for the generation of optimum Remote Sensing (RS) data sets, leading to better interpretation and complementary use of conventional and new remote sensing imagery. It also integrates RS, GIS, and modelling through hypothesis generation, parameter estimation, evaluation and validation. The second subproject facilitates qualitative and quantitative analysis and prediction of the physical aspects of coastal landscape development under the influence of natural processes and human impacts. This subproject is based on the application of remote sensing and dynamic modelling. The third subproject leads to a spatio-temporal working platform which supports data integration of RS and in-situ measurements, and qualitative and quantitative analysis for the prediction of coastal landscape development. Both support decision making in Integrated Coastal Zone Management.     

环境监测优化布点的综合因子得分法

在主成分分析的基础上提出了一种新的环境优化布点的方法——综合因子得分法。该方法先将多维环境指标矩阵投影到其主成分空间,然后将其与对应的方差贡献率进行加权求得综合因子得分,综合因子得分值越大表示该监测点综合环境质量越差,根据综合因子得分值的大小就可对监测点样本集进行合理分类。应用实例表明,该方法用于环境监测优化布点,具有计算简便、快速,计算结果稳健,分析合理,易于推广等优点。     

铸造生产企业环评重点及清洁生产分析

金属铸造企业,特别是铸铁生产企业是机械加工行业的重要组成部分之一,本文以中国北车集团沈阳机车车辆有限责任公司铸造系统技术改造为例,针对该厂对铸造系统的改造前后所用工艺及设备的不同,剖析在进行该类项目环评过程中的重点及该类项目的清洁生产工艺情况。     

含油污水中胶质和沥青质含量的紫外测定方法

探讨用紫外分光光度计快速测定经Al2O3吸附色谱柱分离后的含油污水中胶质?沥青质含量的方法,并且用国内外分析原油及渣油时所通用的四组分分析方法做对比实验,二者相对误差一般小于±5%?实验表明不同油田含油污水中胶质?沥青质含量不同,在污水处理剂的研制及筛选中,应考虑油的组成的影响