Functional values of stabilimenta in a wasp spider, Argiope bruennichi: support for the prey-attraction hypothesis

Many orb-weaving spiders decorate their webs with conspicuous ultraviolet (UV)-reflective stabilimenta. The prey-attraction hypothesis suggests that stabilimenta are visually attractive to prey and thus may increase the spiders’ foraging success. However, previous studies on the function of stabilimenta have produced conflicting results in Argiope species. Using a combination of field and laboratory studies, we examined whether the linear stabilimentum of Argiope bruennichi contributes to prey interception. We recorded prey interceptions in 53 webs with stabilimenta and 37 equally-sized webs without stabilimenta, classifying captured prey according to their taxonomical group and size. On average, 6.2?±?4.7 prey items were intercepted in webs with stabilimenta, while 3.2?±?2.9 items were intercepted in webs without stabilimenta. The effects of stabilimenta on foraging success appear to be due to increased interception of UV-sensitive insect pollinators, including 20 families of Diptera, Hymenoptera, Coleoptera, and Lepidoptera. The mean number of UV-sensitive prey was 4.4?±?3.6 in webs with stabilimenta compared with 1.8?±?2.1 in webs without stabilimenta. Webs with and without stabilimenta did not differ in the mean number of UV-nonsensitive prey captured. The linear stabilimentum showed strong positive effects on the interception of large prey: webs with stabilimenta captured more than twice as many large prey (≥5?mm) than webs without stabilimenta, whereas there was only a slight difference in the interception rates for small prey (<5?mm). Comparisons among different Argiope species suggest that the stabilimentum may have different adaptive functions in different species or ecological contexts.     

Distribution of uranium contamination in weathered fractured saprolite/shale and ground water

The objective of this study was to determine how structure, stratigraphy, and weathering influence fate and transport of contaminants (particularly U) in the ground water and geologic material at the Department of Energy (DOE) Environmental Remediation Sciences Department (ERSD) Field Research Center (FRC). Several cores were collected near four former unlined adjoining waste disposal ponds. The cores were collected, described, analyzed for U, and compared with ground water geochemistry from surrounding multilevel wells. At some locations, acidic U-contaminated ground water was found to preferentially flow in small remnant fractures weathering the surrounding shale (nitric acid extractable U [U(NA)] usually < 50 mg kg(-1)) into thin (<25 cm) Fe oxide-rich clayey seams that retain U (U(NA) 239 to 375 mg kg(-1)). However, greatest contaminant transport occurs in a 2 to 3 m thick more permeable stratigraphic transition zone located between two less permeable, and generally less contaminated zones consisting of (i) overlying unconsolidated saprolite (U(NA) < 0.01 to 200 mg kg(-1)) and (ii) underlying less-weathered bedrock (U(NA) generally < 0.01 to 7 mg kg(-1)). In this transition zone, acidic (pH < 4) U-enriched ground water (U of 38 mg L(-1)) has weathered away calcite veins resulting in greater porosity, higher hydraulic conductivity, and higher U contamination (U(NA) 106 to 745 mg kg(-1)) of the weathered interbedded shale and sandstone. These characteristics of the transition zone produce an interval with a high flux of contaminants that could be targeted for remediation.     

Soil pollution assessment and identification of hyperaccumulating plants in chromated copper arsenate (CCA) contaminated sites, Korea

In recent decades, heavy metal contamination in soil adjacent to chromated copper arsenate (CCA) treated wood has received increasing attention. This study was conducted to determine the pollution level (PL) based on the concentrations of Cr, Cu and As in soils and to evaluate the remediative capacity of native plant species grown in the CCA contaminated site, Gangwon Province, Korea. The pollution index (PI), integrated pollution index (IPI), bioaccumulation factors (BAF_shoots and BAF_roots) and translocation factor (TF) were determined to ensure soil contamination and phytoremediation availability. The 19 soil samples from 10 locations possibly contaminated with Cr, Cu and As were collected. The concentrations of Cr, Cu and As in the soil samples ranged from 50.56-94.13 mg kg⁻¹, 27.78-120.83 mg kg⁻¹, and 0.13-9.43 mg kg⁻¹, respectively. Generally, the metal concentrations decreased as the distance between the CCA-treated wood structure and sampling point increased. For investigating phytoremediative capacity, the 19 native plant species were also collected in the same area with soil samples. Our results showed that only one plant species of Iris ensata, which presented the highest accumulations of Cr (1120 mg kg⁻¹) in its shoot, was identified as a hyperaccumulator. Moreover, the relatively higher values of BAF_shoot (3.23-22.10) were observed for Typha orientalis, Iris ensata and Scirpus radicans Schk, suggesting that these plant species might be applicable for selective metal extraction from the soils. For phytostabilization, the 15 plant species with BAF_root values > 1 and TF values < 1 were suitable; however, Typha orientalis was the best for Cr.     

Examination of Critical Factors Related to Summer Chlorophyll a Concentration in the Sueo Dam Reservoir, Republic of Korea

This study examined critical factors related to the short-term variation of algae growth in reservoirs during the summer. To this end, statistical tests were carried out at a small dam reservoir to determine how chemical factors (e.g., nutrient concentrations) and physical factors (e.g., theoretical and relative residence times, temperature) influenced the chlorophyll a (Chl-a) concentration. Statistical tests revealed that, although phosphorus (P) concentration was significant for Chl-a, residence time had much stronger relationship to Chl-a concentration than chemical factors. In addition, the study verified that relative residence time (RRT) best explained the relation of water status to algae growth. RRT was found to be useful in identifying water status related to the summer algae bloom. Finally, this study raised the possibility of inhibiting summer algae growth by operating dam reservoirs moderately. These findings need to be seriously considered when reservoir operators establish effective strategies for water quality management in summer.     

Application of phosphate-solubilizing bacteria for enhancing bioavailability and phytoextraction of cadmium (Cd) from polluted soil

In this study, phosphate-solubilizing bacteria (PSB), Bacillus megaterium, were used to enhance Cd bioavailability and phytoextractability of Cd from contaminated soils. This strain showed a potential for directly solubilizing phosphorous from soils more than 10 folds greater than the control without inoculation. The results of pot experiments revealed that inoculation with B. megaterium significantly increased the extent of Cd accumulation in Brassica juncea and Abutilon theophrasti by two folds relative to the uninoculated control. The maximum Cd concentrations due to inoculation were 1.6 and 1.8 mg Cd g⁻¹ plant for B. juncea and A. theophrasti after 10 wk, respectively. The total biomass of A. theophrasti was not significantly promoted by the inoculation treatment, yet the total biomass of B. juncea increased from 0.087 to 0.448 g. It is also worth to mention that B. juncea predominantly accumulates Cd in its stems (39%) whereas A. theophrasti accumulates it in its leaves (68%) after 10 wk. The change of the Cd speciation indicated that inoculation of B. megaterium as PSB increased the bioavailabilty of Cd and consequently enhanced its uptake by plants. The present study may provide a new insight for improving phytoremediation using PSB in the Cd-contaminated soils.     

Gas-phase elemental mercury removal in a simulated combustion flue gas using TiO2 with fluorescent light

A previously proposed technology incorporating TiO₂ into common household fluorescent lighting was further tested for its Hg⁰ removal capability in a simulated flue-gas system. The flue gas is simulated by the addition of O₂, SO₂, HCl, NO, H₂O, and Hg⁰, which are frequently found in combustion facilities such as waste incinerators and coal-fired power plants. In the O₂ + N₂ + Hg⁰ environment, a Hg⁰ removal efficiency (η_Hg) greater than 95% was achieved. Despite the tendency for η_Hg to decrease with increasing SO₂ and HCl, no significant drop was observed at the tested level (SO₂: 5–300 ppm_v, HCl: 30–120 ppm_v). In terms of NO and moisture, a significant negative effect on η_Hg was observed for both factors. NO eliminated the OH radical on the TiO₂ surface, whereas water vapor caused either the occupation of active sites available to Hg⁰ or the reduction of Hg₀ by free electron. However, the negative effect of NO was minimized (η_Hg > 90%) by increasing the residence time in the photochemical reactor. The moisture effect can be avoided by installing a water trap before the flue gas enters the Hg⁰ removal system.

Implications: This paper reports a novel technology for a removal of gas-phase elemental mercury (Hg⁰) from a simulated flue gas using TiO₂-coated glass beads under a low-cost, easily maintainable household fluorescent light instead of ultraviolet (UV) light. In this study, the effects of individual chemical species (O₂, SO₂, HCl, NO, and water vapor) on the performance of the proposed technology for Hg⁰ removal are investigated. The result suggests that the proposed technology can be highly effective, even in real combustion environments such as waste incinerators and coal-fired power plants.     

Determinants of homeowners' attitudes to the installation of high-voltage overhead transmission lines

This article deals comprehensively with factors which influence attitudes to the placement of high-voltage overhead transmission lines (HVOTLs). It employs an analytical schema which links the initial stimulus of the power lines' proposal in an area to Background and Socio-economic independent variables and a set of mediating variables. From a survey of 600 residents in three different domiciliary settings in Queensland, Australia, results indicate an absence of positive attitudes and, at best, neutral ones to HVOTL placement. By multinomial logistic regression, the study probes the grounds behind negativity and extreme negativity, uncovering direct links between these attitudes and certain of the variables included in the analytical schema.     

模拟生物反应器加速产甲烷过程研究

渗滤液原液回灌易导致填埋垃圾产甲烷过程的滞后,从而对甲烷收集利用产生不利影响。通过3根实验室模拟生物反应器,研究了原液回灌(C1)、渗滤液好氧预处理后回灌(C2)和原液回灌+垃圾层上部通风曝气(C3)3种填埋方式下的填埋气产气规律。结果表明,C1甲烷浓度经历短暂上升,达到19.5%后开始逐渐降低,产甲烷速率和产甲烷总量均很低;C2甲烷浓度逐渐上升,在第121天时甲烷浓度达到50%,产甲烷最高速率和产甲烷总量分别为0.31 L/(kg·d)和25.2 L/kg。在停止上部垃圾层通风曝气后,C3甲烷浓度迅速上升,在81 d时甲烷浓度便达到50%以上,最大产甲烷速率和产甲烷总量分别为0.22 L/(kg·d)和16.0 L/kg。对各模拟柱填埋气可回收性评价结果表明,C3填埋气可回收利用比例最高,C2略低,C1在实验期间内则无可回收利用气体产生。     

Contamination of polychlorinated biphenyls and organochlorine pesticides in breast milk in Korea: Time-course variation,influencing factors,and exposure assessment

Breast milk is a noninvasive specimen to assess maternal and infant exposure to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). In this study, 206 breast milk samples were collected from 87 participants during lactation, at <7, 15, 30, or 90 days postpartum in four cities in Korea. The total concentrations of PCBs (ΣPCB) and OCPs (ΣOCP) ranged from <LOQ to 84.0 (median: 12.1) ng g⁻¹ lipid weight and from <LOQ to 559 (median: 144) ng g⁻¹ lipid weight, respectively. The residue levels of these contaminants measured in our study were relatively lower than those reported for European, African and Asian populations. Within a month postpartum typically after day seven the levels of ΣPCB and ΣOCP significantly increased. Some OCP compounds were correlated with maternal age, BMI, parity, and delivery mode. Certain types of dietary habits such as seafood and noodle consumption were significantly associated with ΣPCB and ΣOCP. The estimated daily intakes (EDIs) of ΣPCB and ΣOCP were 45.2–127 ng kg⁻¹ bw day⁻¹ and 625–1259 ng kg⁻¹ bw day⁻¹ during lactation, respectively, which are lower than the threshold values proposed by the US EPA and Health Canada. The exposure of Korean infants to chlordanes via breast milk had a potential health risk which deserves further investigation.