An Analytical Review of Environmental Justice Research: What Do We Really Know?

This article presents a review of major empirical research on environmental justice. Forty-two empirical research studies spanning three decades were evaluated and categorized on the basis of how well they meet reasonable scientific standards. Twelve of those studies are described and critiqued in detail, and an overview of trends in the literature is presented. The author concludes that the empirical foundations of environmental justice are so underdeveloped that little can be said with scientific authority regarding the existence of geographical patterns of disproportionate distributions and their health effects on minority, low-income, and other disadvantaged communities. If environmental managers and policy-makers do not recognize the high levels of empirical uncertainty surrounding the issue, they are apt to attribute an empirically unwarranted level of concreteness to the empirical research findings, thus leading to poorly conceptualized and therefore potentially harmful policy and management decisions.     

Different modes of resource variation provide a critical test of ideal free distribution models

Ideal free distribution (IFD) models are perhaps the group of mathematical models of behavior that have been the most widely and successfully applied by empiricists. These models can be applied to nearly any situation in which consumers compete—by any mechanism—for resources that are patchily distributed in their environment. Although IFD models have come to be broadly accepted, experiments that simultaneously test more than a single prediction are rare. Instead, investigators normally either test (1) for a relationship between the distribution of consumers and the distribution of resources or (2) whether average fitnesses are equal across resource patches. We conducted experiments with pea aphids (Acyrthosiphon pisum Harris) feeding on two patches of fava beans (Vicia faba L.) to fully independently parameterize an IFD model with interference competition and then test quantitative predictions about aphid spatial distributions and the payoffs of patch choice. We found a precise fit between aphids’ predicted and observed reproductive successes. Furthermore, by varying patch “quality” in two ways, we were able to show that aphid distributions vary with the mode of resource variation in the predicted manner: aphids (1) matched resources when patches varied in size but not quality and (2) overmatched the good patch when patches varied in quality but not size (predicted as a consequence of weak interference). The close correspondence between quantitative predictions of the model with observed behaviors suggests that IFD theory is a framework with more explanatory power than is generally appreciated.     

Adsorption behavior of RH‐5992 insecticide onto sandy and clay loam forest soils

Abstract

Adsorption‐desorption behavior of RH‐5992 [Mimic®, N'‐t‐butyl‐N'‐(3,5‐dimethylbenzoyl)‐N‐(4‐ethylbenzoyl) hydrazine] in sandy and clay loam forest soils was studied using the batch equilibrium method. Adsorption was higher in the clay loam soil than in the sandy loam, and increased linearly with RH‐5992 concentration, but decreased with increasing pH and temperature. The adsorption data fit better to the Freundlich, than to the Langmuir equation. The K_D (linear adsorption constant) and K_F (Freundlich constant) were similar for each soil at 5, 15 and 25°C and decreased with increase of temperature, indicating that the enthalpy of adsorption was negative. The exponent of the Freundlich equation was close to unity for both soils at all three temperatures. The low E_a (energy of activation) indicated a diffusion‐controlled process during the initial stages of adsorption. The desorption isotherm differed from that of adsorption, and the linear desorption constant, K_D(d), was ca 25 times higher than the K_D, indicating that adsorption of RH‐5992 was not readily reversible. Evaluation of thermo‐dynamic parameters confirmed the presence of strong bonds between the solute and soil. These findings suggest that RH‐5992 has a limited potential for downward mobility leading to groundwater contamination.     

Response of tree growth to a changing climate in boreal central Canada: A comparison of empirical,process-based,and hybrid modelling approaches

The impact of 2 × CO₂ driven climate change on radial growth of boreal tree species Pinus banksiana Lamb., Populus tremuloides Michx. and Picea mariana (Mill.) BSP growing in the Duck Mountain Provincial Forest of Manitoba (DMPF), Canada, is simulated using empirical and process-based model approaches. First, empirical relationships between growth and climate are developed. Stepwise multiple-regression models are conducted between tree-ring growth increments (TRGI) and monthly drought, precipitation and temperature series. Predictive skills are tested using a calibration–verification scheme. The established relationships are then transferred to climates driven by 1× and 2 × CO₂ scenarios using outputs from the Canadian second-generation coupled global climate model. Second, empirical results are contrasted with process-based projections of net primary productivity allocated to stem development (NPP_s). At the finest scale, a leaf-level model of photosynthesis is used to simulate canopy properties per species and their interaction with the variability in radiation, temperature and vapour pressure deficit. Then, a top-down plot-level model of forest productivity is used to simulate landscape-level productivity by capturing the between-stand variability in forest cover. Results show that the predicted TRGI from the empirical models account for up to 56.3% of the variance in the observed TRGI over the period 1912–1999. Under a 2 × CO₂ scenario, the predicted impact of climate change is a radial growth decline for all three species under study. However, projections obtained from the process-based model suggest that an increasing growing season length in a changing climate could counteract and potentially overwhelm the negative influence of increased drought stress. The divergence between TRGI and NPP_s simulations likely resulted, among others, from assumptions about soil water holding capacity and from calibration of variables affecting gross primary productivity. An attempt was therefore made to bridge the gap between the two modelling approaches by using physiological variables as TRGI predictors. Results obtained in this manner are similar to those obtained using climate variables, and suggest that the positive effect of increasing growing season length would be counteracted by increasing summer temperatures. Notwithstanding uncertainties in these simulations (CO₂ fertilization effect, feedback from disturbance regimes, phenology of species, and uncertainties in future CO₂ emissions), a decrease in forest productivity with climate change should be considered as a plausible scenario in sustainable forest management planning of the DMPF.     

Adapting empirical equations to Lake Kinneret data by using three calibration methods

This paper examines whether the relationships between a number of characteristic limnological variables (suspended particulate matter, turbidity, Secchi depth, light attenuation, and chlorophyll a) determined for temperate lakes are consistent with the relationships found in Mediterranean lakes such as Lake Kinneret. We found that the use of published relationships between lake variables may lead to erroneous results when applied indiscriminately to other lake types.     

On the basic reproduction number and the topological properties of the contact network: An epidemiological study in mainly locally connected cellular automata

We study the spreading of contagious diseases in a population of constant size using susceptible-infective-recovered (SIR) models described in terms of ordinary differential equations (ODEs) and probabilistic cellular automata (PCA). In the PCA model, each individual (represented by a cell in the lattice) is mainly locally connected to others. We investigate how the topological properties of the random network representing contacts among individuals influence the transient behavior and the permanent regime of the epidemiological system described by ODE and PCA. Our main conclusions are: (1) the basic reproduction number (commonly called _R0$R_0$) related to a disease propagation in a population cannot be uniquely determined from some features of transient behavior of the infective group; (2) _R0$R_0$ cannot be associated to a unique combination of clustering coefficient and average shortest path length characterizing the contact network. We discuss how these results can embarrass the specification of control strategies for combating disease propagations.     

Implementing second-best environmental policy under adverse selection

A key obstacle to practical application of mechanism design theory to regulation is the difficulty of obtaining consistent beliefs regarding information that theoretical models assume to be commonly held. This article presents a solution to this problem by developing an easily implemented empirical methodology with which the government can use available data to develop beliefs regarding the technology and distribution of types in a regulated sector characterized by hidden information. Results are used to calibrate a second-best land conservation mechanism and evaluate its cost relative to simpler alternatives.     

Regression analysis of forest damage by marginal models for correlated ordinal responses

Studies on forest damage generally cannot be carried out by common regression models, for two main reasons: Firstly, the response variable, damage state of trees, is usually observed in ordered categories. Secondly, responses are often correlated, either serially, as in a longitudinal study, or spatially, as in the application of this paper, where neighbourhood interactions exist between damage states of spruces determined from aerial pictures. Thus so-called marginal regression models for ordinal responses, taking into account dependence among observations, are appropriate for correct inference. To this end we extend the binary models of Liang and Zeger (1986) and develop an ordinal GEEI model, based on parametrizing association by global cross-ratios. The methods are applied to data from a survey conducted in Southern Germany. Due to the survey design, responses must be assumed to be spatially correlated. The results show that the proposed ordinal marginal regression models provide appropriate tools for analysing the influence of covariates, that characterize the stand, on the damage state of spruce.     

沼泽红假单胞菌去除铅的实验研究

采用沼泽红假单胞菌(Rhodopseudomonas palustris)N菌株进行了去除铅的研究。考查pH、温度、接种量、供氧光照条件等因素对其生长及去除铅的影响。结果表明:菌株生长及去除Pb2+的最优条件是pH为7、厌氧光照、温度为30℃,接种量为0.6g·L-1,Pb2+的去除率可达95%以上;模拟了N菌株去除不同浓度Pb2+的动力学方程。进一步研究不同浓度Pb2+对N菌株细胞中半胱氨酸脱巯基酶比活力的影响,结果显示:Pb2+浓度分别为50,100,150mg·L-1时,可提高半胱氨酸脱巯基酶的活力,而当Pb2+浓度提高到200mg·L-1时则抑制其活力。     

DEVELOPMENT OF PREDICTION EQUATIONS FOR A PHREATIC AQUIFER IN RESPONSE TO INFILTRATION: DIMENSIONAL ANALYSIS1

ABSTRACT: The need for a quick means to predict the subsurface flow into a stream caused the authors to take a different approach to the problem. Dimensional analysis was applied to deduce a functional relationship between the dependent and independent variables. This paper lays the ground work for the development of prediction equations for a phreatic aquifer in response to infiltration.