Optical properties of intact leaves for estimating chlorophyll concentration

Changes in leaf chlorophyll content can serve as relative indicators of plant vigor and environmental quality. This study identified reflectance, transmittance, and absorptance wavebands and band ratios within the 400- to 850-nm range for intact leaves that could be used to estimate extracted leaf chlorophyll per unit leaf area (areal concentration) with minimal error. Leaf optical properties along with chlorophyll a, b, and a + b concentrations were measured for the planar-leaved sweetgum (Liquidambar styraciflua L.), red maple (Acer rubrum L.), wild grape (Vitis rotundifolia Michx.), and switchcane [Arundinaria gigantea (Walter) Muhl.], and for needles of longleaf pine (Pinus palustris Miller). Generally, reflectance, transmittance, and absorptance corresponded most precisely with chlorophyll concentrations at wavelengths near 700 nm, although regressions were also strong in the 550- to 625-nm range. A power function was superior to a simple linear function in yielding low standard deviations of the estimate (s). When data were combined among the planar-leaved species, s values were low at approximately 50 mumol/m2 out of a 940 mumol/m2 range in chlorophyll a + b at best-fit wavelengths of 707 to 709 nm. Minimal s values for chlorophyll a + b ranged from 32 to 62 mumol/m2 across species when band ratios having numerator wavelengths of 693 to 720 nm were used with the application of a power function. Optimal denominator wavelengths for the band ratios were 850 nm for reflectance and transmittance and 400 nm for absorptance. This information can be applied in designing field portable chlorophyll meters and in the landscape-scale remote sensing of plant responses to the environment.     

A DECISION SUPPORT SYSTEM FOR WATER QUALITY DATA AUGMENTATION: A CASE STUDY1

ABSTRACT: Recent developments in water quality monitoring have generated interest in combining non-probability and probability data to improve water quality assessment. The Interagency Task Force on Water Quality Monitoring has taken the lead in exploring data combination possibilities. In this paper we take a developed statistical algorithm for combining the two data types and present an efficient process for implementing the desired data augmentation. In a case study simulated Environmental Protection Agency (EPA) Environmental Monitoring and Assessment Program (EMAP) probability data are combined with auxiliary monitoring station data. Auxiliary stations were identified on the STORET water quality database. The sampling frame is constructed using ARC/INFO and EPA's Reach File-3 (RF3) hydrography data. The procedures for locating auxiliary stations, constructing an EMAP-SWS sampling frame, simulating pollutant exposure, and combining EMAP and auxiliary stations were developed as a decision support system (DSS). In the case study with EMAP, the DSS was used to quantify the expected increases in estimate precision. The benefit of using auxiliary stations in EMAP estimates was measured as the decrease in standard error of the estimate.     

Evaluation of Early Life Stage Fall Chinook Salmon Exposed to Hexavalent Chromium from a Contaminated Groundwater Source

We conducted a laboratory evaluation to assess the risk to early life stage (i.e., eyed egg to swim up) fall Chinook salmon (Oncorhynchus tshawytscha) for exposure to hexavalent chromium from a contaminated groundwater source. Local populations of fall Chinook salmon were exposed to Hanford Site source groundwater that was diluted with Columbia River water. Specific endpoints included survival, development rate, and growth. Tissue burdens of fish were also measured to estimate uptake and elimination rates of chromium. Survival, development, and growth of early life stage fall Chinook salmon were not adversely affected by extended exposures (i.e., 98 day) to hexavalent chromium ranging from 0.79 to 260 μg/l. Survival for all treatment levels and controls exceeded 98% at termination of the test. In addition, there were no differences among the mean lengths and weights of fish among all treatment groups. Whole-body concentrations of chromium in early life stage fall Chinook salmon had a typical dose-response pattern; i.e., those subjected to highest exposure concentrations and longest exposure intervals had higher tissue concentrations. Given the spatial extent of chromium concentrations at the Hanford Site, and the dynamics of the groundwater–river water interface, the current cleanup criterion of 10 μg/l chromium appear adequate to protect early life stage fall Chinook salmon. These findings, together with previous research indicate low risk to these populations.     

Cross-national variation in determinants of climate change concern

ABSTRACT

Our understanding of the determinants of public concern about climate change relies heavily on survey research in the United States. But can those findings be generalized to the rest of the world? Analysis of the Pew Research Center’s 2015 Global Attitudes Survey shows fairly similar patterns in the English-speaking Western democracies and, to a lesser extent, western Europe, but party identification and political ideology matter much less in most of the globe, and demographic factors have very different impacts. Female, younger, and less religious people tend to worry more about climate change in English-speaking Western democracies. In most of the world, however, concern is only weakly correlated with gender, rises with age and religiosity, and is more strongly correlated with education. A new measure of commitment to democratic values proved to be the most consistent predictor of concern globally.     

Social comfort zones for transformative conservation decisions in a changing climate

Novel management interventions intended to mitigate the impacts of climate change on biodiversity are increasingly being considered by scientists and practitioners. However, resistance to more transformative interventions remains common across both specialist and lay communities and is generally assumed to be strongly entrenched. We used a decision-pathways survey of the public in Canada and the United States (n = 1490) to test two propositions relating to climate-motivated interventions for conservation: most public groups are uncomfortable with interventionist options for conserving biodiversity and given the strong values basis for preferences regarding biodiversity and natural systems more broadly, people are unlikely to change their minds. Our pathways design tested and retested levels of comfort with interventions for forest ecosystems at three different points in the survey. Comfort was reexamined given different nudges (including new information from trusted experts) and in reference to a particular species (bristlecone pine [Pinus longaeva]). In contrast with expectations of public unease, baseline levels of public comfort with climate interventions in forests was moderately high (46% comfortable) and increased further when respondents were given new information and the opportunity to change their choice after consideration of a particular species. People who were initially comfortable with interventions tended to remain so (79%), whereas 42% of those who were initially uncomfortable and 40% of those who were uncertain shifted to comfortable by the end of the survey. In short and across questions, comfort levels with interventions were high, and where discomfort or uncertainty existed, such positions did not appear to be strongly held. We argue that a new decision logic, one based on anthropogenic responsibility, is beginning to replace a default reluctance to intervene with nature.     

Collaborative Modeling to Evaluate Water Management Scenarios in the Rio Grande Basin

This article describes the collaborative modeling process and the resulting water resources planning model developed to evaluate water management scenarios in the transboundary Rio Grande basin. The Rio Grande is a severely water stressed basin that faces numerous management challenges as it crosses numerous jurisdictional boundaries. A collaborative process was undertaken to identify and model water management scenarios to improve water supply for stakeholders, the environment, and international obligations of water delivery from Mexico to the United States. A transparent and open process of data collection, model building, and scenario development was completed by a project steering committee composed of university, nongovernmental, and governmental experts from both countries. The outcome of the process was a planning model described in this article, with data and operations that were agreed on by water planning officials in each country. Water management scenarios were created from stakeholder input and were modeled and evaluated for effectiveness with the planning model.     

Biotic resistance to green crab, <Emphasis Type="Italic">Carcinus maenas</Emphasis>, in California bays

The distribution of the introduced European green crab, Carcinus maenas, was investigated in the central California embayments of Bodega Bay Harbor (BBH), Tomales Bay, and Bolinas Lagoon using baited traps and snorkel surveys. Adult green crabs were very spatially limited in all three embayments and occurred primarily in warm, shallow areas that lacked large native Cancer spp. crabs. The green crabs that were found in closest proximity to populations of Cancer spp. exhibited high levels of limb damage and loss; damage was strongly correlated with low ratios of intertidal area: edge, indicative of narrow areas of intertidal that are more easily accessed by large Cancer spp. moving up to forage during periods of tidal inundation. Up to 70% of the green crabs tethered in areas of BBH that are utilized by Cancer spp. experienced limb loss, while those tethered in the marsh, where there are no Cancer spp., were undamaged. The results suggest that the potential distribution of green crabs in the northeastern Pacific will be far less than has been predicted, and that their impacts may be largely attenuated through predation by and competition with native crab species.     

Ozonation effects on emerging micropollutants and effluent organic matter in wastewater: characterization using changes of three-dimensional HP-SEC and EEM fluorescence data

The degradation of effluent organic matter (EfOM) in a municipal wastewater treated by ozonation was characterized using the methods of high-performance size-exclusion chromatography (HP-SEC) and excitation/emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC). The removal of 40 diverse trace-level contaminants of emerging concern (CEC) present in the wastewater was determined as well. Ozonation caused a rapid decrease of the absorbance and fluorescence of the wastewater, which was associated primarily with the oxidation of high and low apparent molecular weight (AMW) EfOM fractions. PARAFAC analysis also showed that components C1 and C2 decreased prominently in these conditions. The EfOM fraction of intermediate molecular weight ascribable to a terrestrial humic-like component (C3) tended to be less reactive toward ozone. Relative changes of EEM fluorescence were quantified using F _max values of PARAFAC-identified components (∆F/F ⁰ _max). Unambiguous relationships between ∆F/F ⁰ _max values and the extent of the degradation of the examined CECs (∆C/C₀) were established. This allowed correlating main parameters of the ∆C/C₀ vs. ∆F/F ⁰ _max relationships with the rates of oxidation of these CECs. The results demonstrate the potential of online measurements of EEM fluorescence for quantitating effects of ozonation on EfOM and micropollutants in wastewater effluents.