Modeling alkene chemistry using condensed mechanisms for conditions relevant to southeast Texas,USA

Alkenes are important in photochemical smog formation in southeast Texas due to their high emissions, especially from industrial sources in and around Houston, and their high reactivities. Therefore, properly characterizing the chemistry of alkenes in condensed mechanisms used in regional photochemical models is important in understanding the formation of ozone and other photochemical air pollutants in Houston. The performance of three versions of the SAPRC condensed chemical mechanism family, for predicting ozone and radical formation, was compared. Simulations were compared to environmental chamber data and ambient data. The analyses showed that separately modeling individual alkenes reactions (especially propene for southeast Texas) has the potential to lead to more accurate simulations of alkene chemistry. Caution must be exercised in un-lumping, however. Testing with different formulations of the 1-butene + O₃ reaction demonstrated the complexity and interconnectedness in choices of stoichiometric parameters for un-lumped species and the extent to which lumped mechanisms are un-lumped.     

贵州省务川地区土法炼汞工人汞蒸汽暴露调查及健康影响评价

为探讨土法炼汞过程中汞蒸汽暴露对炼汞工人健康的影响,测定了贵州省务川土法炼汞区和对照区(贵州省长顺县)人群的尿汞、尿常规参数(pH、葡萄糖、尿胆红素原、潜血、尿蛋白)、尿肌酐和尿β2微球蛋白含量,并对两地区人群进行了详细的健康检查．测定结果显示,土法炼汞区人群尿汞和尿β2微球蛋白的平均含量分别高达779μg·g-1 Cr 和208．5μg·g-1 Cr,远远高于对照区人群的尿汞1．24μg·g-1 Cr和尿β2微球蛋白75．4μg·g-1 Cr．分析表明,务川地区土法炼汞人群遭受了较严重的汞蒸汽暴露,部分暴露人群已经表现出轻度慢性汞中毒的症状,其肾脏已经遭受到一定程度的损伤．     

The seasonal effects of manure management and feeding strategies on hydrogen sulphide emissions from stored dairy manure

Journal of Material Cycles and Waste Management - The influence of temperature and storage time on hydrogen sulphide (H2S) emissions from two different dairy manures was investigated over four...     

Poor correlation between the removal or deposition of pollen grains and frequency of pollinator contact with sex organs

The Science of Nature - Pollinators deposit pollen grains on stigmas and remove pollen grains from anthers. The mechanics of these transfers can now be quantified with the use of high-speed video....     

Spatiotemporal trend analysis of recent river water quality conditions in Japan

In order to promote pollutant monitoring and preservation of water resources, we evaluate the spatiotemporal trends in recent water quality conditions in Japanese rivers. Trend analysis is conducted on the 92 major rivers in Japan using the available water quality data recorded from 1992 to 2005 and the characteristics of major pollutants in these rivers are analyzed. Spatial and temporal analysis of trends for six water quality indicators is conducted using the Mann Kendall test, a non-parametric statistical method. The indicators analyzed are biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), total nitrogen (TN), total phosphorus (TP) and pH. The majority of sampling locations monitoring BOD, COD, TN and TP show trends toward decreasing concentrations over time. Many sampling locations show increasing DO concentrations. Our results show that water quality in Japanese rivers has improved dramatically over the past decade, although there are still problems in some places, most notably in the Hokkaido, Kanto, Kinki and Kyushu regions. The improvements seen in water quality appear to be the result of improved wastewater treatment and other water quality improvement efforts achieved through government initiative.     

Laboratory Measurement of Dry Deposition of Ozone onto Northern Chinese Soil Samples

We used laboratory experiments to investigate surface resistance (R _c) to dry deposition of ozone (O₃) on different types of soil samples collected from the arid deserts and the Loess Plateau of northern China. Furthermore, we measured the factors that affected R _c, which depends on the physical and chemical interaction between trace constituents and the deposition surface, and evaluated deposition velocity (V _d). There was little influence of geometric surface area, soil weight, or O₃ concentration on V _d of O₃. The effect of relative humidity (RH) (i.e. moisture content of the soil) on O₃ uptake was in agreement with results reported in the literature: a distinct RH dependence of V _d and little uptake under water-saturated conditions were observed. R _c values for all the soil samples examined were in the range 0.21–3.3 s mm⁻¹ and were exponentially related to the surface area of the particles and the organic carbon content of each soil sample at RH of both <10 and 60%.     

Body temperature independence of solar radiation in free-ranging loggerhead turtles,Caretta caretta,during internesting periods

Body temperatures, ambient water temperatures, light intensities and vertical positions (depth) of eight loggerhead turtles, Caretta caretta, were monitored by small recorders during internesting periods from 1991 through 1993 off Wakayama Prefecture, Japan. Body temperatures of eight loggerhead turtles were higher than ambient water temperatures through-out their internesting periods. Light intensities were compared with body temperatures and no evidence was obtained to suggest that the raised body temperatures were caused by the direct influence of solar radiation. Body temperatures were kept higher than water temperatures in cloudy weather or even at night. Mean thermal differences between body and water temperatures were significantly different among individuals, and larger turtles had a greater mean thermal difference. Elevations in body temperatures of adult loggerhead turtles can reasonably be assumed to result from the accumulation of metabolically produced heat. Surfacing times (spent at depths shallower than 2 m) of seven turtles were only 10.3 to 38.9% of their internesting periods, with the exception of one turtle who spent 66.3% of her time at the surface. Loggerhead turtles did not seem to bask positively at the sea surface to absorb radiative heat.     

Effects of deicing salt on the vitality and health of two spruce species,Picea abies Karst., and Picea glehnii Masters planted along roadsides in northern Japan

In northern Japan, the growth of Picea abies Karst., and Picea glehnii Masters, which have been planted along the highways, is often suppressed due to several environmental stresses. To examine the adverse effects of deicing salt, the primary source of stress,we measured needle life span, photosynthetic capacity, and water potential and transpiration rate of the two spruce species at a site with damaged trees, near the roadside and a site with healthy trees, located far from the highway. Results from the analysis showed large amounts of sodium and chlorine in the soil and snow at the damaged site. These elements had accumulated in the needles of the spruce. Moreover, physiological traits of the spruce, at the damaged site were also affected. Therefore, we concluded that poor physiological traits might be attributed to an accumulation of deicing salt in the needles, resulting in the suppression of tree growth.     

Assessing noxious effects of dietary exposure to methylmercury,PCBs and Se coexisting in environmentally contaminated rice in male mice

Polychlorinated biphenyls and methylmercury are two of the most ubiquitous environmental contaminants in Guizhou province. Rice is eaten with almost every meal and provides more calories than any single food in Guizhou province. The estimated tolerable daily intake of total mercury, MeHg, Se and PCBs from Guizhou contaminated rice by Chinese people showed that MeHg and/or PCBs exceeded the corresponding limits. The aim of this study was to characterize the effects of exposure to environmental contaminated rice on neurobehavioral development and neurobiological disruptions in mice. Animals were treated from postnatal day (PND) 22 to 91. At PND 26–91 days of age, mice were tested for neurobehavioural development and neurochemical level changes. We showed that dietary exposure to environmentally contaminated rice gave rise to different changes in antioxidants. Reduced superoxide dismutase (SOD) activity and excess increased nitric oxide (NO) indicated aggravation of oxidative status after long-term dietary intake of Hg and PCBs. Neurobehavioral derangement in the central nervous system and significant delay in the Morris water maze test response on PND 91 are correlated with the increased of c-fos/c-jun expression levels in the cerebral cortex. These results suggest that MeHg neurotoxicity might be a greater hazard than that associated with PCB, but PCB may augment the neurobehavioral deficits caused by increased levels of mercury exposure. The simultaneous intake of selenium might have a protective effect on Hg accumulation in the body, and vitamin C might protect mice against the toxic effects of PCBs. However, the protective role of Se and vitamin C is very limited for multiple-agent pollution. Immediately early genes in the brain response to contaminated rice might be dependent on interaction among NO, NO synthase (NOS), SOD and reduced glutathione (GSH). We should be alert to mental health problems in human beings when any kind of Hg- and PCB-polluted food is consumed.     

Regional assessment of marine and estuarine sediment toxicity in Southern California, USA

Sediment toxicity was investigated at 222 stations in the Southern California Bight (SCB) during 2008. This represented the first time that assessment methods established by California's new Sediment Quality Objectives program were employed in a survey of this scale. The goal was to determine the extent and magnitude of sediment toxicity in the SCB, how toxicity compared among specific environments, and whether toxicity has changed over the last decade. Two toxicity tests were used: the 10-day amphipod whole sediment survival test with Eohaustorius estuarius and a 48-h embryo development test with the mussel Mytilus galloprovincialis exposed at the sediment–water interface. Less than 1 % of the area of the SCB was found to be toxic to the amphipod test. No toxicity was found in offshore stations, but 14 % of embayment areas were toxic to the amphipods. The mussel test identified 13 % of the embayment areas to be toxic. Estuary and marina locations had the greatest areal extent of toxicity for both tests. The two toxicity methods agreed that sediments were not toxic at over half of the stations tested. The mussel test showed a greater magnitude of response than the amphipod. Sediment toxicity was shown to have declined in both extent and magnitude from levels measured in 1998 and 2003.