Effect of Accelerated Weathering on Biocomposites Processed by SMC and Compression Molding

The durability of biocomposites utilized for building components has been a subject of recent concern and questioning. To address these concerns, the long-term effects of weathering on biocomposites used as building components were evaluated using an accelerated weatherometer. The biocomposite samples were processed by sheet molding compounding (SMC) panel processing and/or compression molding. The accelerated weatherometer served to expose the samples to ultraviolet radiation (UV), condensation, and water spray at levels pertinent to actual conditions: 48 cycles of UV (340 nm) treatment at 60 °C for 2.5 h was followed by water spray for 0.5 h, and then condensation at 45 °C for 24 h. Twelve cycles were repeated in each test, and the total duration for the complete test was 2016 h. Measurements for color, surface roughness test weight change, and dynamical mechanical analysis were taken at regular intervals of time. It was found that the surface roughness increased, as the color changed, and storage modulus decreased with increases in the exposure time of the samples to accelerated weathering conditions, compared to their properties at the beginning of the test.     

Use of AMS in the marine environment

In recent years, the field of AMS has expanded into many areas of science. This paper reviews a variety of applications of AMS in the marine environment, focusing particularly on recent developments and applications. Following a brief summary of the three main isotope techniques used in environmental studies: dating, tracing and source identification, a number of applications are considered. Traditional (14)C-dating is no longer the dominant application of AMS measurements, and together with measurements of (10)Be, (26)Al and (36)Cl, much of the research is now directed towards an understanding of global climate change via studies of oceanic circulation, atmospheric processes and past climates by cosmic ray exposure dating. Profiles of long-lived cosmogenic radionuclides in sediments and ice cores, as a function of depth and, thus, age, provide key information on past solar variability, production rate changes and atmospheric transport and deposition mechanisms. Useful paleoclimatic information may be derived from these archives both because deposition is influenced by climate and because solar activity (which influences production) and solar radiance (which influences climate) are correlated. In recent years, emphasis has been put on the development and application of AMS techniques for the measurement of heavier long-lived isotopes, including (99)Tc, (129)I, (236)U and other actinide isotopes. AMS combines ultra low detection limits and the possibility to analyse isotope ratios that can be difficult with traditional instruments and has been used in a number of applications on the consequences and uses of releases from nuclear energy. Finally, the use AMS in environmental sciences is expected to expand further in the foreseeable future with long-lived cosmogenic radionuclides contributing to a large body of knowledge on processes involving atmosphere, oceans, ice sheets, biosphere, soils and sediments.     

Evaluation of data quality in lichen biomonitoring studies: the Italian experience

A total of 65 operators involved in lichen mapping studies in central and northwestern Italy underwent quality control tests during five lichen biomonitoring workshops organized between 1999and 2000. The results showed that 75% quantitative accuracy and90% quantitative precision can be regarded as satisfactory levels for lichen biodiversity data; 65% proved to be sufficientfor accuracy of taxonomic identification in the field. Average correct assignment of the interpretative naturality/alteration class was only 48.7%. The results indicated the need for taxonomic training.     

Comparing environmental influences on coral bleaching across and within species using clustered binomial regression

Differential susceptibility among reef-building coral species can lead to community shifts and loss of diversity as a result of temperature-induced mass bleaching events. We evaluate environmental influences on coral colony bleaching over an 8-year period in the Florida Keys, USA. Clustered binomial regression is used to develop models incorporating taxon-specific responses to the environment in order to identify conditions and species for which bleaching is likely to be severe. By building three separate models incorporating environment, community composition, and taxon-specific responses to environment, we show observed prevalence of bleaching reflects an interaction between community composition and local environmental conditions. Environmental variables, including elevated sea temperature, solar radiation, and reef depth, explained 90% and 78% of variability in colony bleaching across space and time, respectively. The effects of environmental variables were only partially explained (33% of variability) by corresponding differences in community composition. Taxon-specific models indicated individual coral species responded differently to local environmental conditions and had different sensitivities to temperature-induced bleaching. For many coral species, but not all, bleaching was exacerbated by high solar radiation. A 25% reduction in the probability of bleaching in shallow locations for one species may reflect an ability to acclimatize to local conditions. Overall, model results indicate predictions of coral bleaching require knowledge of not just the environmental conditions or community composition, but the responses of individual species to the environment. Model development provides a useful tool for coral reef management by quantifying the influence of the local environment on individual species bleaching sensitivities, identifying susceptible species, and predicting the likelihood of mass bleaching events with changing environmental conditions.     

Bet hedging in a guild of desert annuals

Evolutionary bet hedging encapsulates the counterintuitive idea that organisms evolve traits that reduce short-term reproductive success in favor of longer-term risk reduction. It has been widely investigated theoretically, and many putative examples have been cited including practical ones such as the dormancy involved in microbe and weed persistence. However, long-term data on demographic variation from the actual evolutionarily relevant environments have been unavailable to test for its mechanistic relationship to alleged bet hedging traits. I report an association between delayed germination (a bet hedging trait) and risk using a 22-year data set on demographic variation for 10 species of desert annual plants. Species with greater variation in reproductive success (per capita survival from germination to reproduction x per capita fecundity of survivors) were found to have lower average germination fractions. This provides a definitive test using realistic data on demographic variance that confirms the life history prediction for bet hedging. I also showed that the species with greater long-term demographic variation tended to be the ones with greater sensitivity of reproductive success to variation among years in growing-season precipitation.     

Linking soil respiration and water table depth in tropical peatlands with remotely sensed changes in water storage from the gravity recovery and climate experiment

Mitigation and Adaptation Strategies for Global Change - Carbon dioxide (CO2) emissions from Southeast Asia peatlands are contributing substantially to global anthropogenic emissions to the...     

Formation and control of nitrogenous DBPs from Western Australian source waters: Investigating the impacts of high nitrogen and bromide concentrations

We studied the formation of four nitrogenous DBPs(N-DBPs) classes(haloacetonitriles,halonitromethanes, haloacetamides, and N-nitrosamines), as well as trihalomethanes and total organic halogen(TOX), after chlorination or chloramination of source waters. We also evaluated the relative and additive toxicity of N-DBPs and water treatment options for minimisation of N-DBPs. The formation of halonitromethanes, haloacetamides, and N-nitrosamines was higher after chloramination and positively correlated with dissolved organic nitrogen or total nitrogen. N-DBPs were major contributors to the toxicity of both chlorinated and chloraminated waters. The strong correlation between bromide concentration and the overall calculated DBP additive toxicity for both chlorinated and chloraminated source waters demonstrated that formation of brominated haloacetonitriles was the main contributor to toxicity. Ozone–biological activated carbon treatment was not effective in removing N-DBP precursors. The occurrence and formation of N-DBPs should be investigated on a case-by-case basis, especially where advanced water treatment processes are being considered to minimise their formation in drinking waters, and where chloramination is used for final disinfection.