A Tale of Two Rivers: Implications of Water Management Practices for Mussel Biodiversity Outcomes During Droughts

Droughts often pose situations where stream water levels are lowest while human demand for water is highest. Here we present results of an observational study documenting changes in freshwater mussel communities in two southern US rivers during a multi-year drought. During a 13-year period water releases into the Kiamichi River from an impoundment were halted during droughts, while minimum releases from an impoundment were maintained in the Little River. The Kiamichi observed nearly twice as many low-flow events known to cause mussel mortality than the Little, and regression tree analyses suggest that this difference was influenced by reduced releases. During this period mussel communities in the Kiamichi declined in species richness and abundance, changes that were not observed in the Little. These results suggest that reduced releases during droughts likely led to mussel declines in one river, while maintaining reservoir releases may have sustained mussel populations in another.     

Debromination of polybrominated diphenyl ether-99 (BDE-99) in carp (Cyprinus carpio) microflora and microsomes

Based on previous findings in dietary studies with carp (Cyprinus carpio), we investigated the mechanism of 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) debromination to 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) using liver and intestinal components. In vitro aerobic and anaerobic experiments tested the ability of carp intestinal microflora to debrominate BDE-99. No debromination of BDE-99 to BDE-47 was observed in microfloral samples; therefore, carp enzymatic pathways were assessed for debromination ability. After sixty-min incubation, intestine and liver microsomes exhibited 83+/-34% and 106+/-18% conversions, respectively, of BDE-99 to BDE-47; with no significant (p>0.05) difference between organ debromination capabilities. Microsomal incubations with BDE-99, enzyme cofactors and competing substrates assessed the potential mechanisms of debromination. The presence of NADPH in the microsomal assay did not significantly (p>0.05) affect BDE-99 debromination, which suggest that cytochrome P450 enzymes are not the main debrominating pathway for BDE-99. Co-incubation of BDE-99 spiked microsomes with reverse thyronine (rT3) significantly (p<0.05) decreased the debromination capacity of intestinal microsomes indicating the potential of catalytic mediation via thyroid hormone deiodinases. The significant findings of this study are that intestinal microflora are not responsible for BDE-99 debromination, however, it is an endogenous process which occurs with approximately equal activity in intestine and liver microsomes and it can be inhibited by rT3.     

Investigation of time-resolved atmospheric conditions and indoor/outdoor particulate matter concentrations in homes with gas and biomass cook stoves in Nogales,Sonora, Mexico

This paper reports findings from a case study designed to investigate indoor and outdoor air quality in homes near the United States–Mexico border. During the field study, size-resolved continuous particulate matter (PM) concentrations were measured in six homes, while outdoor PM was simultaneously monitored at the same location in Nogales, Sonora, Mexico, during March 14–30, 2009. The purpose of the experiment was to compare PM in homes using different fuels for cooking, gas versus biomass, and to obtain a spatial distribution of outdoor PM in a region where local sources vary significantly (e.g., highway, border crossing, unpaved roads, industry). Continuous PM data were collected every 6 seconds using a valve switching system to sample indoor and outdoor air at each home location. This paper presents the indoor PM data from each home, including the relationship between indoor and outdoor PM. The meteorological conditions associated with elevated ambient PM events in the region are also discussed. Results indicate that indoor air pollution has a strong dependence on cooking fuel, with gas stoves having hourly averaged median PM₃ concentrations in the range of 134 to 157 μg m^?3 and biomass stoves 163 to 504 μg m^?3. Outdoor PM also indicates a large spatial heterogeneity due to the presence of microscale sources and meteorological influences (median PM₃: 130 to 770 μg m^?3). The former is evident in the median and range of daytime PM values (median PM₃: 250 μg m^?3, maximum: 9411 μg m^?3), while the meteorological influences appear to be dominant during nighttime periods (median PM₃: 251 μg m^?3, maximum: 10,846 μg m^?3). The atmospheric stability is quantified for three nighttime temperature inversion episodes, which were associated with an order of magnitude increase in PM10 at the regulatory monitor in Nogales, AZ (maximum increase: 12 to 474 μg m^?3).

Implications:Regulatory air quality standards are based on outdoor ambient air measurements. However, a large fraction of time is typically spent indoors where a variety of activities including cooking, heating, tobacco smoking, and cleaning can lead to elevated PM concentrations. This study investigates the influence of meteorology, outdoor PM, and indoor activities on indoor air pollution (IAP) levels in the United States–Mexico border region. Results indicate that cooking fuel type and meteorology greatly influence the IAP in homes, with biomass fuel use causing the largest increase in PM concentration.     

Heuristics and biases in cyber security dilemmas

Cyber security often depends on decisions made by human operators, who are commonly considered a major cause of security failures. We conducted 2 behavioral experiments to explore whether and how cyber security decision-making responses depend on gain–loss framing and salience of a primed recall prior experience. In Experiment I, we employed a 2 × 2 factorial design, manipulating the frame (gain vs. loss) and the presence versus absence of a prior near-miss experience. Results suggest that the experience of a near-miss significantly increased respondents’ endorsement of safer response options under a gain frame. Overall, female respondents were more likely to select a risk averse (safe) response compared with males. Experiment II followed the same general paradigm, framing all consequences in a loss frame and manipulating recall to include one of three possible prior experiences: false alarm, near-miss, or a hit involving a loss of data. Results indicate that the manipulated prior hit experience significantly increased the likelihood of respondents’ endorsement of a safer response relative to the manipulated prior near-miss experience. Conversely, the manipulated prior false-alarm experience significantly decreased respondents’ likelihood of endorsing a safer response relative to the manipulated prior near-miss experience. These results also showed a main effect for age and were moderated by respondent’s income level.     

Artificial intelligence modeling to evaluate field performance of photocatalytic asphalt pavement for ambient air purification

In recent years, the application of titanium dioxide (TiO₂) as a photocatalyst in asphalt pavement has received considerable attention for purifying ambient air from traffic-emitted pollutants via photocatalytic processes. In order to control the increasing deterioration of ambient air quality, urgent and proper risk assessment tools are deemed necessary. However, in practice, monitoring all process parameters for various operating conditions is difficult due to the complex and non-linear nature of air pollution-based problems. Therefore, the development of models to predict air pollutant concentrations is very useful because it can provide early warnings to the population and also reduce the number of measuring sites. This study used artificial neural network (ANN) and neuro-fuzzy (NF) models to predict NO_x concentration in the air as a function of traffic count (T_r) and climatic conditions including humidity (H), temperature (T), solar radiation (S), and wind speed (W) before and after the application of TiO₂ on the pavement surface. These models are useful for modeling because of their ability to be trained using historical data and because of their capability for modeling highly non-linear relationships. To build these models, data were collected from a field study where an aqueous nano TiO₂ solution was sprayed on a 0.2-mile of asphalt pavement in Baton Rouge, LA. Results of this study showed that the NF model provided a better fitting to NO_x measurements than the ANN model in the training, validation, and test steps. Results of a parametric study indicated that traffic level, relative humidity, and solar radiation had the most influence on photocatalytic efficiency.     

The interaction of temperature and sucrose concentration on foraging preferences in bumblebees

Several authors have found that flowers that are warmer than their surrounding environment have an advantage in attracting pollinators. Bumblebees will forage preferentially on warmer flowers, even if equal nutritional reward is available in cooler flowers. This raises the question of whether warmth and sucrose concentration are processed independently by bees, or whether sweetness detectors respond to higher sugar concentration as well as higher temperature. We find that bumblebees can use lower temperature as a cue to higher sucrose reward, showing that bees appear to process the two parameters strictly independently. Moreover, we demonstrate that sucrose concentration takes precedence over warmth, so that when there is a difference in sucrose concentration, bees will typically choose the sweeter feeder, even if the less sweet feeder is several degrees warmer.     

Investigation of the time evolved spatial distribution of urban PM2.5 concentrations and aerosol composition during episodic high PM events in Yuma,AZ

An interdisciplinary field study designed to investigate the spatial and temporal variability of atmospheric aerosols during high particulate matter (PM) events along the US–Mexico border near Yuma, AZ was run during the week of March 18, 2007. The experiments were designed to quantify chemical composition and physical phenomena governing the transport of aerosols generated from episodic high PM events. The field study included two micrometeorological monitoring sites; one rural and one urban, equipped with sonic anemometers, continuous particulate concentration monitors and ambient aerosol collection equipment. In addition to the two main monitoring sites, five additional locations were equipped with optical particle counters to allow for the investigation of the spatial and temporal distribution of PM_2.5 in the urban environment. In this paper, the meteorological and turbulence parameters governing the distribution and concentration of PM_2.5 in the urban environment for two high-wind erosion events and one burning event are compared. The interaction between local atmospheric conditions and the particulate distribution is investigated. Results indicate that a single point measurement in the urban area of Yuma may not be sufficient for determining the ambient PM concentrations that the local population experiences; all three high PM events indicated PM_2.5 varied considerably with maximum urban concentrations 5–10 times greater than the measured minima. A comparison of inorganic and carbonaceous content of the aerosols for the three high PM events is presented. The comparison shows an increase in silicon during crustal dust events and an increase in elemental and organic carbon during the burn event. Additional surface chemistry analysis, using time-of-flight secondary ion mass spectrometry (ToF-SIMS), for aerosols collected at the urban and rural sites during the burn event are discussed. The surface chemistry analysis provides positive ion mass spectra of organic and inorganic species in the ambient aerosol, and can be used to determine the type of combustion process that contributed to an increase in PM concentration during the burn event.     

一个从酸化和金属污染中恢复的湖泊历史悠久的水蚤属(Daphnia)群落的重现

通过综合采用古湖泊学技术和分子遗传技术重现汉纳(Hannah)湖--个从工业酸化、金属污染及动物灭绝中恢复的湖泊--中水蚤属(Daphnia)群落组成的长期型式.像许多浮游动物一样,水蚤属可以产出能生存几十年,甚至一百年以上的滞育卵.然而,过去20年D.mendotae在汉纳湖中的出现可能是从其他附近湖泊扩散的结果,而不是从沉积物卵库移居而来的.我们利用聚合酶连锁反应(PCR),单股构象多形现象(SSCP)以及排序进行的成因测试结果表明,D.mendotae滞育卵在过去250年沉积物记录中没有发现,在该地区金属冶炼作业之前,该生物群落由D.pulicaria控制.在湖泊化学复原之后这一物种的变化与早期湖泊酸性的历史变化一致.在汉纳湖的整个远古历史中,环境波动可能决定了群落组成.将这一分子一古湖泊学方法扩展到其他湖泊应该有助于更准确地阐述生物复原过程.     

Policy challenges and approaches for the conservation of mangrove forests in Southeast Asia

Many drivers of mangrove forest loss operate over large scales and are most effectively addressed by policy interventions. However, conflicting or unclear policy objectives exist at multiple tiers of government, resulting in contradictory management decisions. To address this, we considered four approaches that are being used increasingly or could be deployed in Southeast Asia to ensure sustainable livelihoods and biodiversity conservation. First, a stronger incorporation of mangroves into marine protected areas (that currently focus largely on reefs and fisheries) could resolve some policy conflicts and ensure that mangroves do not fall through a policy gap. Second, examples of community and government comanagement exist, but achieving comanagement at scale will be important in reconciling stakeholders and addressing conflicting policy objectives. Third, private‐sector initiatives could protect mangroves through existing and novel mechanisms in degraded areas and areas under future threat. Finally, payments for ecosystem services (PES) hold great promise for mangrove conservation, with carbon PES schemes (known as blue carbon) attracting attention. Although barriers remain to the implementation of PES, the potential to implement them at multiple scales exists. Closing the gap between mangrove conservation policies and action is crucial to the improved protection and management of this imperiled coastal ecosystem and to the livelihoods that depend on them.