Effects of soiling and cleaning on the reflectance and solar heat gain of a light-colored roofing membrane

A roof with high solar reflectance and high thermal emittance (e.g., a white roof) stays cool in the sun, reducing cooling power demand in a conditioned building and increasing summertime comfort in an unconditioned building. The high initial solar reflectance of a white membrane roof (circa 0.8) can be lowered by deposition of soot, dust, and/or biomass (e.g., fungi or algae) to about 0.6; degraded solar reflectances range from 0.3 to 0.8, depending on exposure. We investigate the effects of soiling and cleaning on the solar spectral reflectances and solar absorptances of 15 initially white or light-gray polyvinyl chloride membrane samples taken from roofs across the United States. Black carbon and organic carbon were the two identifiable strongly absorbing contaminants on the membranes. Wiping was effective at removing black carbon, and less so at removing organic carbon. Rinsing and/or washing removed nearly all of the remaining soil layer, with the exception of (a) thin layers of organic carbon and (b) isolated dark spots of biomass. Bleach was required to clear these last two features. At the most soiled location on each membrane, the ratio of solar reflectance to unsoiled solar reflectance (a measure of cleanliness) ranged from 0.41 to 0.89 for the soiled samples; 0.53 to 0.95 for the wiped samples; 0.74 to 0.98 for the rinsed samples; 0.79 to 1.00 for the washed samples; and 0.94 to 1.02 for the bleached samples. However, the influences of membrane soiling and cleaning on roof heat gain are better gauged by fractional variations in solar absorptance. Solar absorptance ratios (indicating solar heat gain relative to that of an unsoiled membrane) ranged from 1.4 to 3.5 for the soiled samples; 1.1 to 3.1 for the wiped samples; 1.0 to 2.0 for the rinsed samples; 1.0 to 1.9 for the washed samples; and 0.9 to 1.3 for the bleached samples.     

Coping with uncertainty: a call for a new science-policy forum

The scientific and policy worlds have different goals, which can lead to different standards for what constitutes "proof" of a change or phenomena, and different approaches for characterizing and conveying uncertainty and risk. These differences can compromise effective communication among scientists, policymakers, and the public, and constrain the types of socially compelling questions scientists are willing to address. In this paper, we review a set of approaches for dealing with uncertainty, and illustrate some of the errors that arise when science and policy fail to coordinate correctly. We offer a set of recommendations, including restructuring of science curricula and establishment of science-policy forums populated by leaders in both arenas, and specifically constituted to address problems of uncertainty.     

Relationship between hydrocarbon measurements and toxicity to a chironomid, fish larva and daphnid for oils and oil spill chemical treatments in laboratory freshwater marsh microcosms

This research investigated the extent to which various common hydrocarbon measures can be used to predict toxicity to freshwater aquatic organisms due to fouling by oil. Actual toxicity results, on laboratory freshwater marsh microcosms using two water-column species and a benthic species, were described earlier. The hydrocarbon measures used were TPH(g), TPH(FID), TPH(MS), TTAH (sum of 41 target aromatic hydrocarbons), principal components of 41 TAHs, and each individual TAH. In general, toxicity was more closely related to TPH(MS) levels than to TPH(FID) and (especially) TPH(g) levels. The strongest relationships were found for TTAH levels and for the principal components of the TAHs. Regressions of toxicity on many individual TAHs were also strong, with a single group of compounds explaining as much as 59% of the variation in survival. While the various regressions were highly significant statistically and at times able to accurately predict broad differences in toxicity, the high variation in survival at a specific hydrocarbon concentration indicates that these hydrocarbon measures can not substitute for actual toxicity determinations in accurately ranking the toxicity of samples from oiled freshwater marshes.     

Defensive anointing: extended chemical phenotype and unorthodox ecology

Summary. Many animals acquire substances on their integument from heterospecifics through anointing. In active or self-anointing, animals rub against scent sources or they apply them by appendage or mouth. In passive anointing, animals adsorb emitted chemicals. Most investigators suggest that chemicals appropriated via anointing deter predators, ectoparasites, and/or microbial pathogens. Similarly, nesting birds and brood parasites of social insects acquire chemicals from and reside unmolested near or within insect colonies. The acquisition through anointing of chemicals that deter predators, ectoparasites, microbial pathogens, and other offenders, i.e. defensive anointing, constitutes an extended phenotype: the genetic machinery by which defensive compounds are synthesized does not reside with the anointing organisms, but the sensory mechanisms and/or behavioral tendencies by which chemicals are appropriated from heterospecifics do. The ecological relationships between anointing organisms and chemical donors, and between chemical donors and those responding to chemicals appropriated via anointing, may be unorthodox. Interactions between anointing organisms and chemical donors typically entail abrasive contact with or other damage to the latter. These encounters sometimes are evidenced by telltale marks on chemical donors or by chemicals deposited on the integument of anointing organisms. The organisms furnishing chemicals and those affected by them may not interact, and they may even occupy different habitats, because mobile anointing organisms are the medium by which chemicals are disseminated. Thus, in allelochemical studies where anointing is involved, species can be tested, with ecological legitimacy, using chemicals from organisms they might fail to interact with in nature. Practical implications of anointing stem from its potential importance in conservation and captive management, where consideration is given to the protection that animals derive by accessing topically acquired chemicals from heterospecifics.     

The use of systems diagrams for environmental impact assessment: Procedures and an application

The utility of systems diagrams and of energy as a unit of measure for environmental impact assessment is illustrated using results from the White Sands Missile Range, New Mexico Environmental Impact Statement. A set of procedures for developing and evaluating the diagrams is given and applied to White Sands. The utility of results obtained using this method is compared to those obtained from other methods, and the inadequacies of each are discussed.These procedures guide data collection; organize and summarize data; make explicit interactions between the environment and the “proposed project”; place various kinds of impacts and alternatives in perspective with each other and with the entire system; identify components of a macroscale system which need microscale analysis; and permit quantification of total impact and quantitative comparisons of impact types, of alternatives, and of environmental control strategies. The procedures do not guarantee that important impacts have not been overlooked, do not deal with so called aesthetic impacts, and do not guarantee that the appropriate system boundary has been chosen.Impacts at White Sands were evaluated at two system levels of detail. At a macroscale, five types of impacts resulting from missile range activities were analyzed. Results indicated that stresses on the environment caused by those activities represent 1.0% of the natural energy flow through the system. At a more detailed level of analysis, the effect of water consumption by the Missile Range on the aquifer from which the water is obtained was analyzed by means of a hydrologic model. Model simulations indicated that salt water intrusion into the aquifer was eminent and identified two aquifer management strategies that could prevent that intrusion.     

Salinity-temperature relationships in the queen scallop Chalamys opercularis

The effects of reduced salinities on different size-ranges of Chlamys opercularis (L.) were studied at various temperatures using 3 methods of analysis: median lethal mortality over 24 h (LD₅₀, 24 h); surface-response analysis; time-mortality relationships. Reduced salinities ranging from 16 to 28 were lethal after a 24 h exposure, depending on the temperature and size of the scallop. Mortality increased at extremes of temperature, and spat appeared to have a slightly greater tolerance than larger individuals. Observations were also made on behavioural responses and byssus attachment at reduced salinities.     

Diet induced differences in carbon isotope fractionation between sirenians and terrestrial ungulates

Carbon isotope differences (Δ¹³C) between bioapatite and diet, collagen and diet, and bioapatite and collagen were calculated for four species of sirenians, Dugong dugon (Müller), Trichechus manatus (Linnaeus), Trichechus inunguis (Natterer), and the extinct Hydrodamalis gigas (Zimmerman). Bone and tooth samples were taken from archived materials collected from populations during the mid eighteenth century (H. gigas), between 1978 and 1984 (T. manatus, T. inunguis), and between 1997 and 1999 (D. dugon). Mean Δ¹³C values were compared with those for terrestrial ungulates, carnivores, and six species of carnivorous marine mammals (cetaceans = 1; pinnipeds = 4; mustelids = 1). Significant differences in mean δ¹³C values among species for all tissue types were detected that separated species or populations foraging on freshwater plants or attached marine macroalgae (δ¹³C values < −6‰; Δ¹³C_{bioapatite–diet} ∼14‰) from those feeding on marine seagrasses (δ¹³C values > −4‰; Δ¹³C_{bioapatite–diet} ∼11‰). Likewise, Δ¹³C_{bioapatite–collagen} values for freshwater and algal-foraging species (∼7‰) were greater than those for seagrass-foraging species (∼5‰). Variation in Δ¹³C values calculated between tissues and between tissues and diet among species may relate to the nutritional composition of a species’ diet and the extent and type of microbial fermentation that occurs during digestion of different types of plants. These results highlight the complications that can arise when making dietary interpretations without having first determined species-specific Δ¹³C_{tissue–diet} values. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.