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301.
302.
Stanislaw Lozecznik Richard Sparling Jan A. Oleszkiewicz Shawn Clark Jamie F. VanGulck 《Waste management (New York, N.Y.)》2010,30(11):2030-2036
In this study, an anaerobic sequencing batch reactor (ASBR) was operated with leachate from Brady Road Municipal Landfill in Winnipeg, Manitoba, Canada. Leachate was collected twice from the same cell at the landfill, during the first and 70th day of the study, and then fed into the ASBR. The ASBR was seeded at the start-up with biosolids from the anaerobic digester from Winnipeg’s North End Water Pollution Control Center (NEWPCC). Due to the higher COD and VFA removal rates measured with the second batch of leachate, an increase of approximately 0.3 pH units was observed during each cycle (from pH 7.2 to 7.5). In addition, CO2 was produced between cycles at constant temperature where a fraction of the CO2 became dissolved, shifting the CO2/bicarbonate/carbonate equilibrium. Concurrent with the increase in pH and carbonate, an accumulation of fixed suspend solids (FSS) was observed within the ASBR, indicating a buildup of inorganic material over time. From it, Ca2+ and Mg2+ were measured within the reactor on day 140, indicating that most of the dissolved Ca2+ was removed within cycles. There is precedence from past researches of clogging in leachate-collection systems (Rowe et al., 2004) that changes in pH and carbonate content combined with high concentrations of metals such as Ca2+ and Mg2+ result in carbonate mineral precipitants. A parallel study investigated this observation, indicating that leachate with high concentration of Ca2+ under CO2 saturation conditions can precipitate out CaCO3 at the pH values obtained between digestion cycles. These studies presented show that methanogenesis of leachate impacts the removal of organic (COD, VFA) as well as inorganic (FSS, Ca2+) clog constituents from the leachate, that otherwise will accumulate inside of the recirculation pipe in bioreactor landfills. In addition, a robust methanogenesis of leachate was achieved, averaging rates of 0.35 L CH4 produced/g COD removed which is similar to the theoretical removal of 0.4 L CH4/g COD. Therefore, using methanogenesis of leachate prior to recirculation in bioreactor landfills will help to (1) control clog formation within leachate pipes and (2) produce an important additional source of energy on-site. 相似文献
303.
Johanneke E. Oosten Carin Magnhagen Charlotte K. Hemelrijk 《Behavioral ecology and sociobiology》2010,64(5):793-802
Most studies of animal personality attribute personality to genetic traits. But a recent study by Magnhagen and Staffan (Behav
Ecol Sociobiol 57:295–303, 2005) on young perch in small groups showed that boldness, a central personality trait, is also shaped by social interactions
and by previous experience. The authors measured boldness by recording the duration that an individual spent near a predator
and the speed with which it fed there. They found that duration near the predator increased over time and was higher the higher
the average boldness of other group members. In addition, the feeding rate of shy individuals was reduced if other members
of the same group were bold. The authors supposed that these behavioral dynamics were caused by genetic differences, social
interactions, and habituation to the predator. However, they did not quantify exactly how this could happen. In the present
study, we therefore use an agent-based model to investigate whether these three factors may explain the empirical findings.
We choose an agent-based model because this type of model is especially suited to study the relation between behavior at an
individual level and behavioral dynamics at a group level. In our model, individuals were either hiding in vegetation or feeding
near a predator, whereby their behavior was affected by habituation and by two social mechanisms: social facilitation to approach
the predator and competition over food. We show that even if we start the model with identical individuals, these three mechanisms
were sufficient to reproduce the behavioral dynamics of the empirical study, including the consistent differences among individuals.
Moreover, if we start the model with individuals that already differ in boldness, the behavioral dynamics produced remained
the same. Our results indicate the importance of previous experience and social interactions when studying animal personality
empirically. 相似文献
304.
Radium (Ra) removal by an unconventional sorbent, a modified bauxite refinery residue (MBRR), is investigated for a groundwater extracted in Missouri, USA. The MBRR treatment causes substantial reductions of both gross α and combined Ra activities from 0.955 ± 0.005 and 0.66 ± 0.005 Bq L to below detection limits (0.037 Bq L or 1 pCi L). Column breakthrough occurs at 0.555 Bq L for gross α and 0.185 Bq L for combined Ra (15 and 5 pCi L; USEPA's maximum contaminant levels) after 54 and 40 d run time, respectively. At 84 d the MBRR media continues to remove 24.3% of raw water gross α and 39.7% of the combined Ra. The treatment effluent has an initial pH of 10.9, outside the USEPA guides (6.5-8.5); this may be readily mitigated by posttreatment acid injection, or by raw water blending. The MBRR simultaneously removes other potentially hazardous trace elements (e.g., Cu, Zn, and Fe) to extremely low concentrations. In addition, toxicity characteristic leaching procedure testing of spent MBRR suggests that metals are bound tightly, such that it is nonhazardous, permitting cost-effective disposal to landfill without special confinement or storage. Consequently, MBRR may be utilized as an alternative adsorbent for treating Ra-contaminated groundwater. 相似文献
305.
A major challenge in forecasting the ecological consequences of climate change is understanding the relative importance of changes to mean conditions vs. changes to discrete climatic events, such as storms, frosts, or droughts. Here we show that the first major storm of the growing season strongly influences the population dynamics of three rare and endangered annual plant species in a coastal California (USA) ecosystem. In a field experiment we used moisture barriers and water addition to manipulate the timing and temperature associated with first major rains of the season. The three focal species showed two- to fivefold variation in per capita population growth rates between the different storm treatments, comparable to variation found in a prior experiment imposing eightfold differences in season-long precipitation. Variation in germination was a major demographic driver of how two of three species responded to the first rains. For one of these species, the timing of the storm was the most critical determinant of its germination, while the other showed enhanced germination with colder storm temperatures. The role of temperature was further supported by laboratory trials showing enhanced germination in cooler treatments. Our work suggests that, because of species-specific cues for demographic transitions such as germination, changes to discrete climate events may be as, if not more, important than changes to season-long variables. 相似文献
306.
Lisa A. Taylor David L. Clark Kevin J. McGraw 《Behavioral ecology and sociobiology》2011,65(5):1133-1146
In many animals, conspicuous coloration functions as a quality signal. Indicator models predict that such colors should be
variable and condition dependent. In Habronattus pyrrithrix jumping spiders, females are inconspicuously colored, while males display brilliant red faces, green legs, and white pedipalps
during courtship. We tested the predictions of the indicator model in a field study and found that male body condition was
positively correlated with the size, hue, and red chroma of a male’s facial patch and negatively correlated with the brightness
of his green legs. These traits were more condition dependent than non-display colors. We then tested a dietary mechanism
for condition dependence using two experiments. To understand how juvenile diet affects the development of coloration, we
reared juvenile spiders on high- and low-quality diets and measured coloration at maturity. To understand how adult diet affects
the maintenance of coloration, we fed wild-caught adults with high- or low-quality diets and compared their coloration after
45 days. In the first experiment, males fed high-quality diet had redder faces, suggesting that condition dependence is mediated
by juvenile diet. In the second experiment, red coloration did not differ between treatments, suggesting that adult diet is
not important for maintaining the color after it is produced at maturity. Diet had no effect on green coloration in either
experiment. Our results show different degrees of condition dependence for male display colors. Because red is dependent on
juvenile diet, it may signal health or foraging ability. We discuss evidence that green coloration is age dependent and alternatives
to indicator models for colorful displays in jumping spiders. 相似文献
307.
Clara Illi Josefine Koenigbauer Wolfgang Henrich Laura Fangmann Charlotte Reinhardt Sophia Ossmann Alexander Weichert 《黑龙江环境通报》2023,43(11):1459-1462
Germline pathogenic variants in isocitrate dehydrogenase 1 (IDH1) can lead to a rare neurodevelopmental disorder called metaphyseal chondromatosis with D-2-hydroxyglutaric aciduria, including severe skeletal and cerebral anomalies. To the best of our knowledge, no prenatal case of an IDH1 pathogenic variant has been reported in literature. Somatic sequence variants in IDH1/2 genes are described in distinct cancers, premalignant diseases and rare inherited metabolic disorders. Amniocentesis and further genetic testing including trio exome sequencing were performed due to suspicious findings on a second trimester routine prenatal ultrasound examination. The fetus was found to have growth restriction, cerebral abnormalities (ex vacuo hydrocephalus, cerebellar and vermian hypoplasia, corpus callosum dysgenesis), brachycephaly, narrow chest, persistent left superior vena cava, liver calcifications, hyperechogenic bowel, short tubular bones and joint contractures. A de novo heterozygous variant in the IDH1 gene was detected via trio exome sequencing. The prenatal diagnosis of a de novo pathogenic variant in IDH1 in a fetus with the described phenotype, obtained through trio exome sequencing, helped parents and providers with an informed decision making about pregnancy management. 相似文献
308.
Nigel N. Clark David L. McKain Jr. Terence S. Higgins 《Journal of the Air & Waste Management Association (1995)》2021,71(1):3-22
ABSTRACT Emissions levels from current gasoline spark-ignited engines are low, and emissions changes associated with the blending of ethanol into gasoline are small and difficult to quantify. Addition of ethanol, with a high blending octane number, allows a reduction in aromatics in market gasoline. Blending behavior of ethanol is nonlinear, altering the distillation curve, including the 50% temperature point, T50. Increase in gasoline direct injection (GDI) engine technology in the fleet challenges ability of older models based on port fuel injection (PFI) results to predict the overall air quality impact of ethanol blending. Five different models derived from data collected through U.S. Environmental Protection Agency Energy Policy Act (EPAct) programs were used to predict LA92 Phase 1 particulate matter (PM) emissions for summer regular (SR) E0 (gasoline with 0% ethanol by volume), E10 (gasoline with 10% ethanol) and E15 (gasoline with 15% ethanol). Substantial reductions of PM for E10 and E15 relative to E0 were predicted when aromatics were displaced by ethanol to maintain octane rating. SR E0 and E10 were also matched to linear combinations of EPAct fuels and results showed a 35% PM reduction for SR E10 relative to SR E0. For GDI vehicles the Coordinating Research Council (CRC) E-94-3 study found that E10 had 23% or 29% PM increase. However, CRC E-129 found an E10 PM reduction of 10% when one E0 fuel and its splash blended (SB) E10 were compared. Both CRC project E-129 SB data and fuel triplets selected from the EPAct study showed variation for E15 emissions, although E-129 suggests that E15 in GDI offers about a 25% reduction of PM with respect to E0. Overall, data suggest that ethanol blending offers a modest to a substantial reduction of cold-start PM mass if aromatic levels of the finished products are reduced in response to ethanol addition. Implications: Studies of exhaust emissions effects of ethanol blending with gasoline vary in conclusions. Blending properties are nonlinear. Modeling of real-world emissions effects must consider all fuel composition adjustments and property changes associated with ethanol addition. Aromatics are reduced in E10 or E15, compared with E0, and distillation changes. PFI-derived models show reductions in cold-start PM for expected average E10 versus E0 pump fuel, due to reduced aromatic content. Relative emissions effects from older technology (PFI) engines do not predict newer engine (GDI) results reliably, but recent GDI data show reduced cold-start PM when ethanol displaces aromatics. 相似文献
309.
Dromard Charlotte R. Devault Damien A. Bouchon-Navaro Yolande Allénou Jean-Pierre Budzinski Hélène Cordonnier Sébastien Tapie Nathalie Reynal Lionel Lemoine Soazig Thomé Jean-Pierre Thouard Emmanuel Monti Dominique Bouchon Claude 《Environmental science and pollution research international》2022,29(1):51-60
Environmental Science and Pollution Research - The organochlorine pollution by chlordecone, an insecticide spread in the past in banana plantations, is now recognized as a major ecological,... 相似文献
310.