Stationarity: Wanted Dead or Alive?1

Lins, Harry F. and Timothy A. Cohn, 2011. Stationarity: Wanted Dead or Alive? Journal of the American Water Resources Association (JAWRA) 47(3):475‐480. DOI: 10.1111/j.1752‐1688.2011.00542.x Abstract: Aligning engineering practice with natural process behavior would appear, on its face, to be a prudent and reasonable course of action. However, if we do not understand the long‐term characteristics of hydroclimatic processes, how does one find the prudent and reasonable course needed for water management? We consider this question in light of three aspects of existing and unresolved issues affecting hydroclimatic variability and statistical inference: Hurst‐Kolmogorov phenomena; the complications long‐term persistence introduces with respect to statistical understanding; and the dependence of process understanding on arbitrary sampling choices. These problems are not easily addressed. In such circumstances, humility may be more important than physics; a simple model with well‐understood flaws may be preferable to a sophisticated model whose correspondence to reality is uncertain.     

Changes in vegetation persistence across global savanna landscapes, 1982–2010

We present a global analysis of the changing face of vegetation persistence in savanna ecosystems by boreal seasons. We utilized nearly 30 years of monthly normalized difference vegetation index data in an innovative time-series approach and developed associated statistical significance tests, making the application of continuous vegetation metrics both more rigorous and more useful to research. We found that 8,000,000–11,000,000 km² of savanna have experienced significant vegetation decline during each season, while 20,000,000–23,000,000 km² have experienced an increase in vegetation persistence during each season, relative to the baseline period (1982–1985). In addition, with the exception of the March–April–May season, which is mixed, the pattern of significant vegetation persistence in the Northern Hemisphere is almost exclusively positive, while it is negative in the Southern Hemisphere. This finding highlights the increasing vulnerability of the Southern Hemisphere savanna landscapes; either resulting from changing precipitation regimes (e.g., southern Africa) or agricultural pressures and conversions (e.g., South America).     

Profiles in persistence: A latent profile analysis of multilevel coping strategies enacted among women in the sciences

This study examines the different ways women in Science, Technology, Engineering, and Mathematics (STEM) occupations cope with systemic stereotype threat. Although it is theorized that women in STEM engage multiple and simultaneous strategies in response to stereotype threat, rarely are coping strategies studied in combination. This leaves us with an incomplete picture of coping behavior. To address this gap, we adopt a person-centered approach to examine nine multilevel stereotype threat management strategies. Drawing from a sample of 515 women in male-dominated STEM occupations, we use latent profile analysis (LPA) to uncover three distinct profiles (Preservationists, Protectors, and Protagonists) which differ by degree of strategy engagement and preferred location of response (intrapersonal, interpersonal, and institutional). Our findings also show that profile membership is differently associated with person-related (gender centrality, science identity, and stigma consciousness) and work-related factors (perceived organizational support, negative emotions at work, and exit due to gender-based bias) relevant to persistence. This work demonstrates the value of a person-centered approach in distinguishing coping profiles within and between STEM women in a naturalistic context. It also suggests that organizations can better support STEM women by tailoring interventions that account for differences in coping behavior.     

农药在生态环境中的持久性及残留的研究方法

本文报导农药在生态环境中的持久性及残的研究方法，它包括农药在作物、土壤和水等环境介质中的持外性，以及农药在这些介质中中的残留量与农药的施用量和施药次数的关系等方面的内容，本文还介绍了农药在作物中最高残留限量与安全间隔期的计算方法。     

Variance and Uncertainty in the Expected Number of Occurrences in Reserve Selection

Abstract:  Reserve selection often concerns the design of reserve networks for the long-term maintenance of biodiversity. We considered uncertainty in the context of three common reserve-selection formulations, the expected number of populations, proportional coverage of land-cover types, and the probability of having at least one population. By uncertainty, we mean variance in the outcome of any probability-based reserve selection formulation. A typical reserve-selection formulation might ask for the least expensive set of sites that contains n populations per species. It is implicit here that this requirement concerns the expected number of populations, which actually is obtained only with a 50% chance. If the requirement is changed to select the least expensive set of sites that gives n populations per species with a 95% probability, the number of sites required in the solution increases and the identity of the sites is changed toward sites that have high probabilities of persistence (or occurrence) and low associated binomial variance. Anthropogenic threat is one factor that may cause probabilistic uncertainty in the context of proportional area coverage.     

Utility of Measuring Abundance versus Consistent Occupancy in Predicting Biodiversity Persistence

Abstract:  The primary goals of reserve selection are to represent all chosen units of biodiversity and to ensure their long-term persistence while minimizing costs. We considered two simple proxies of species persistence: a time series of point-count data to calculate abundance and a time series of presence–absence data to calculate permanence (a measure of consistent occupancy over time). Using two 10-year intervals of data from the North American Breeding Bird Survey, we compared the performance of each measure at predicting persistence 18 years later. For nonrare species, abundance and permanence predicted persistence similarly well. We performed complementarity-based reserve selections with data on species abundance and permanence (from 1970 to 1979) and then evaluated the effectiveness of the reserve networks at maintaining species populations and efficiency in land use (data from 1997 to 2006). Abundance proved a better predictor of future local persistence than permanence, which justifies the relatively larger financial and temporal costs of collecting a time series of point-count data to estimate abundance. If future extinction events were used as a measure of reserve-network effectiveness, the performance of abundance and permanence did not differ markedly. Nevertheless, when future abundance, which is a more sensitive measure of network effectiveness, was used, abundance was significantly better than permanence at selecting longer-term, high-quality, species-specific habitat but required larger reserves to do so .     

THE PROBABILITY OF CONSECUTIVE RAINLESS DAYS1

ABSTRACT: A major objective of this work was to develop a method applicable to the Intermountain region for estimating the probability of n consecutive dry days, where n ≤ 30 days. One result was a computationally simple method of producing the desired estimates directly from the rainfall record. For a consecutive dry-day period of n days, these estimates are equivalent to those obtained from a Markov model of order n-1. The efficacy of a simple Markov model was also evaluated. In this climatic region, the simple Markov model produces probability estimates of consecutive dry days that are too conservative, especially at long dry-day periods. In this data set, it was found that the longer the dry-day sequence, the more conservative the Markov estimate. The source of these conservative estimates is the strong dry-day persistence, which is characteristic of summer weather in the Intermountain region. In this region, the best estimates of the probability of consecutive dry days are probably those obtained directly from a representative rainfall record and smoothed by the partial sums of a fourier Series.     

Persistence characteristics of operationally sprayed fenitrothion in nearby unsprayed areas of a conifer forest ecosystem in New Brunswick

Abstract

Persistence characteristics of operationally sprayed fenitrothion were investigated in various substrates sampled from neighbouring unsprayed areas in New Brunswick. Air, water, sediment, aquatic plants, fish, balsam fir [Abies balsamea (L.) Mill] foliage, forest soil and litter samples were collected from random sampling locations selected within 200 m from the operational spray blocks. The same substrates were resampled from the same plots and from the same locations about a year later just prior to the commencement of the operational spraying. Control samples were collected from an unsprayed site, near Sault Ste. Marie, Ontario. All samples were analysed for fenitrothion, by gas‐liquid chromatography. Except the fish samples all the substrates collected during the time of operational spraying contained low but detectable levels of fenitrothion. When collected a year later prior to the operational spray program, only balsam fir showed any detectable levels (detection limit, 0.01 ppm) of the chemical. All other samples showed no fenitrothion residues (detection limit for air, 10 ng/m³; for water, 0.01 ppb; and for other samples, 0.01 ppm). The findings confirmed that fenitrothion does not persist for an extended period of time in the aquatic substrates. The conifer foliage, however, showed persistent residues at a level of about 0.55 ppm even after the winter months, although there was no indication of accumulation of the chemical as a result of repeated exposure. The study demonstrated that the conifer needles acted as a micro sink for the chemical which showed a tendency to persist in the leaf tissues for a considerable length of time.     

广州地区PBDEs长距离迁移潜力和总持久性模拟

运用TaPL3.0模型对7种PBDEs同系物在广州地区的长距离迁移潜力(LRTP)和总持久性(Pov)进行了模拟研究,并通过灵敏度分析得到了模型的关键参数.研究结果显示,PBDEs排放至大气中,特征迁移距离(CTD)为296~811km,均值为557km;Pov为19~279d,均值为184d;PBDEs平均约有73.8%分布在土壤中,16.9%分布在沉积物中,9.3%分布在其他三相中.PBDEs排放到水体时,CTD为3090~4291km,均值为3731km;Pov范围为228~854d,均值为731d;平均约92.1%分布在沉积物中,6.8%分布在水相中,1.1%在大气、土壤和植被相中.BDE47迁移潜力最大,BDE209易残留于源区形成点源性污染.PBDEs各同系物主要分布在沉积物和土壤中.随着溴代程度升高,CTD逐渐降低,Pov逐渐升高,与国外研究趋势一致.     

The EU-project ERAPharm. Incentives for the further development of guidance documents?

- Triggered by the detection of a large variety of pharmaceuticals in surface waters, soils and groundwaters across the world (e.g. Halling- Sørensen et al. 1998, Daughton & Ternes 1999, Jones et al. 2001, Heberer 2002) and the widespread occurrence of endocrine active compounds and related effects in the environment (e.g. Purdom et al. 1994, Tyler et al. 1998, Vethaak et al. 2002), pharmaceuticals in the environment have become an issue for both the scientific and the public community. During the last few years, our understanding of the fate and effects of pharmaceuticals in the environment has progressed significantly. However, there are still a number of uncertainties concerning the effects of pharmaceuticals on the environment and the assessment of potential exposure (e.g. Hanisch et al. 2004, Salomon 2005). These uncertainties will be addressed by the EU-project ‘Environmental risk assessment of pharmaceuticals’ (ERAPharm). This project, a specific targeted research project, is carried out within the priority ‘Global change and ecosystems’ of the 6th framework programme of the European Union. ERAPharm has started on 1st October 2004; the project duration is three years.