Deposition velocity of PM2.5 sulfate in the summer above a deciduous forest in central Japan

In order to increase knowledge of aerosol dry deposition for the regional assessment of acid deposition and transboundary air pollution in East Asia, an experimental study on PM2.5 sulfate deposition was implemented in the early summer of 2009. The experimental field was located in a deciduous forest at the foot of Mt. Asama, central Japan. Aerosol fluxes were obtained using the aerodynamic gradient method. Three aerosol samplers were placed on an experimental tower at 21, 24 and 27 m above the ground surface, and collected PM2.5 on filters for chemical analysis. Vertical concentration differences between 21 m and 27 m of PM2.5 sulfate were detected significantly when the concentration exceeded 1 μg m^?3. Mean deposition velocity was estimated to be 0.9 ± 1.0 cm s^?1 in the daytime and 0.3 ± 0.3 cm s^?1 in the nighttime. In the case that a height-dependent correction in the roughness sub-layer was taken into account, the deposition velocities increased more, especially in daytime. Higher deposition velocities in the daytime were associated with larger friction velocities and unstable conditions. The deposition velocities observed in this study were in agreement with other experimental results found in the literature. On the other hand, they were higher than those calculated by theoretical models. Two empirical parameterizations (Wesely, M.L., Cook, D.R., Hart, R.L., 1985. Measurement and parameterization of particulate sulfur dry deposition over grass. Journal of Geophysical Research 90, 2131–2143; Ruijgrok, W., Tieben, H., Eisinga, P., 1997. The dry deposition of particles to a forest canopy: a comparison of model and experimental results. Atmospheric Environment 31, 399–415) were validated by the observations. The general trend of higher daytime and lower nighttime deposition velocities was similar among the observation and the two parameterizations. The large variability found in the measurement was not reproduced by the parameterizations, because it is attributable to random error from the differences between the samplers. The observations were in accordance with the parameterization of Ruijgrok et al. (1997) for a forest, although much larger than that of Wesely et al. (1985) for grasslands. This indicates the large difference in aerosol deposition velocities between forests and grasslands.     

Distribution and binding pattern of benzo(a)pyrene in rat liver,lung and kidney constituents after oral administration

Orally administered ³H‐benzo(a)pyrene (BP) was persistent in protein fraction of liver, lung and kidney. The radioactivity in this fraction increased with time after administration and accounted for about 50%, 40% and 65% of total radioactivity in liver, lung and kidney, respectively at 48 hr. The BP metabolites binding proteins were located in cytosol and had molecular weights of 40,000–60,000 and 80,000–100,000 as determined by gel filtration and polyacrylamide gel disc electrophoresis. In addition, at 48hr after administration, about 80% of radioactivity in high molecular weight protein fraction was found to be precipitated by trichloroacetic acid treatment.

These results suggest that BP metabolites might be transported by and are persistent in these protein fractions of liver, lung and kidney if the intake of BP is continuous. These proteins, therefore, appeared to be closely related to cell toxicity or mutagenicity in these organs as well as DNA.     

The role of diatom resting stages in the onset of the spring bloom in the East China Sea

The abundance and species composition of diatoms were investigated along the PN line from the Okinawa Islands to the inner continental shelf in the East China Sea in the early spring of 1996. Viable diatom resting stages in sediments on the shelf were also enumerated by the extinction dilution method (most probable number method). Clear differentiation in the water masses was observed, with less saline, cold water (shelf water) on the shelf region, and warm, saline water (Kuroshio water) prevalent off the shelf and on the shelf edge. In the Kuroshio water, the abundance of diatoms was generally low but species diversity of diatoms was relatively high. In contrast, the spring bloom of diatoms was clearly observed in the shelf water where the water column was weakly stratified. The bloom was dominated by Chaetoceros debilis, contributing occasionally >80% of the diatom community. Resting stages of this species were also the most abundant taxon in the sediments on the shelf. Resuspension of the sediment during winter mixing of the water column should have enabled the resting stages to germinate at the surface. Subsequent vegetative growth after germination led to the formation of an early spring bloom of C. debilis when the water column was stratified and light availability had increased. Intermittent resuspension of sediment on the shelf, driven by strong winds and tidal currents, probably provides opportunities for diatoms with a resting stage to exploit favorable conditions for their germination and subsequent vegetative growth. It is further suggested that complex hydrographic conditions in the East China Sea result in a dynamic bloom with contributions by both autochthonous and allochthonous species.Communicated by T. Ikeda, Hakodate     

Methane and CO2 fluxes from an Indonesian peatland used for sago palm (Metroxylon sagu Rottb.) cultivation: Effects of fertilizer and groundwater level management

Tropical peatland is a vast potential land source for biological production, but peatland is a major natural source of greenhouse gases, especially methane (CH₄). It is important to evaluate the changes in greenhouse gas emissions induced by cultivation practices for sustainable agricultural use of tropical peatland. We investigated the effects of fertilizer application and the groundwater level on CH₄ and carbon dioxide (CO₂) fluxes in an Indonesian peat soil. The crop cultivated was sago palm (Metroxylon sagu Rottb.), which can grow on tropical peat soil without drainage and yield great amounts of starch. CH₄ emission through sago palm plants was first estimated by collecting gas samples immediately after cutting sago suckers using the closed chamber method. The CH₄ fluxes ranged from negative values to 1.0 mg C m⁻² h⁻¹. The mean CH₄ flux from treatment with macroelements (N, P, and K) and microelements (B, Cu, Fe, and Zn) applied at normal rates did not differ significantly from that of the No fertilizer treatment, although increasing the application rates of macroelements or microelements by 10-fold increased the CH₄ flux by a factor of two or three. The relationship between CH₄ flux and the groundwater table was regressed to a logarithmic equation, which indicated that to maintain a small CH₄ flux, the groundwater table should be maintained at <−45 cm. The CO₂ fluxes ranged between 24 and 150 mg C m⁻² h⁻¹, and were not significantly affected by either fertilizer treatments or the groundwater level. The inclusion of sago palm suckers in a chamber increased CH₄ emission from the peat soil significantly. Thus, gas emissions mediated by certain kinds of palm plants should not be disregarded.     

Yearly variation in characteristics and health risk of polycyclic aromatic hydrocarbons and nitro-PAHs in urban shanghai from 2010–2018

This study encompassed the regular observation of nine polycyclic aromatic hydrocarbons (PAHs) and three nitro-PAHs (NPAHs) in particulate matter (PM) in Shanghai in summer and winter from 2010 to 2018. The results showed that the mean concentrations of ?PAHs in summer decreased by 24.7% in 2013 and 18.1% in 2017 but increased by 10.2% in 2015 compared to the data in 2010. However, the mean concentrations of ?PAHs in winter decreased by 39.7% from 2010 (12.8 ± 4.55 ng/m³) to 2018 (7.72 ± 3.33 ng/m³), and the mean concentrations of 1-nitropyrene in winter decreased by 79.0% from 2010 (42.3 ± 16.1 pg/m³) to 2018 (8.90 ± 2.09 pg/m³). Correlation analysis with meteorological conditions revealed that the PAH and NPAH concentrations were both influenced by ambient temperature. The diagnostic ratios of PAHs and factor analysis showed that they were mainly affected by traffic emissions with some coal and/or biomass combustion. The ratio of 2-nitrofluoranthene to 2-nitropyrene was near 10, which indicated that the OH radical-initiated reaction was the main pathway leading to their secondary formation. Moreover, backward trajectories revealed different air mass routes in each sampling period, indicating a high possibility of source effects from the northern area in winter in addition to local and surrounding influences. Meanwhile, the mean total benzo[a]pyrene-equivalent concentrations in Shanghai in winter decreased by 50.8% from 2010 (1860 ± 645 pg/m³) to 2018 (916 ± 363 pg/m³). These results indicated the positive effects of the various policies and regulations issued by Chinese authorities.     

2005年-2008年亚洲东部沙尘暴的定期数字记录监测

地处亚洲东部的中国长春,蒙古乌兰巴托和日本鹿儿岛,作为亚洲沙尘暴的地面监测站点,用数码相机全自动定时拍摄记录天空的数字照片,通过分析数字照片数据上像素点的信息和建筑的能见度,来判断沙尘暴事件的发生及强度。对比分析了2005年-2008年冬春季节数字监测数据与NOAA,MT-SAT和Terra,Aqua/MOD IS的卫星遥感图片以及其他相关沙尘天气的报道。在监测的图片数据上,持续1-2天的强沙尘暴天气能够被清楚的识别,轻度的沙尘天气与云量较多的天气较难区别。     

Chitin biodegradation and wound healing in tree bark tissues

Chitin biodegradation and wounded bark tissue healing were demonstrated in several evergreen and deciduous trees by dressing with a sheet of chitin-containing films or sponges. Chitinase activities in the tree bark tissues around the wounds were enhanced by this treatment up to four times those of the untreated wounds. Significant seasonal changes of chitinase activities were observed with the bark and leaf tissues of deciduous trees, but few with those of evergreen trees. A sheet of chitin films implanted or dressed in the tree bark tissues was biodegraded within 4 to 24 weeks after implantation and was assimilated into the wounded bark tissues, resulting in the stimulation of the wounded bark tissue healing.     

Effect of grinding and heating on Ni2+ uptake properties of waste paper sludge

Uptake properties of Ni2+ were examined for unmilled and milled paper sludge calcined at various temperatures to develop a new usage of waste paper sludge. Since paper sludge mainly consists of cellulose ([C6H(10)O5]n) fibers, calcite (CaCO3), kaolinite (Al2Si2O5(OH)4) and talc (Mg3Si(4)O(10)(OH)2), amorphous and crystalline CaO(MgO)-Al(2)O(3)-SiO(2) compounds are formed by calcining paper sludge. Wet and dry milling treatments were performed to accelerate solid-state reaction to form the above mentioned target compounds. The crystalline phases originally present decompose at increasing calcining temperature (up to 800 degrees C) in the order cellulose 相似文献   

Uptake and distribution of iodine in rice plants

Rice (Oryza sativa L.) plants were cultivated in an experimental field and separated at harvest into different components, including polished rice, rice bran, hull, straw, and root. The contents of iodine in these components and the soil were determined by inductively coupled plasma-mass spectrometry and radiochemical neutron activation analysis, respectively. Iodine content varied by more than three orders of magnitude among the plant components. Mean concentration of iodine in the entire plants was 20 mg kg(-1) dry weight, and the concentration of iodine in the surface soil (0-20 cm depth) was 48 mg kg(-1). The highest concentration of iodine (53 mg kg(-1) dry weight) was measured in root and the lowest concentration (0.034 mg kg(-1) dry weight) in polished rice. While the edible component (polished rice) accounted for 32% of the total dry weight, it contained only 0.055% of iodine found in the entire rice plants. Atmospheric gaseous iodine (5.9 ng m(-3)) was estimated to contribute <0.2% of the total iodine content in the biomass of rice plants; therefore nearly all of the iodine in the rice plants was a result of the uptake of iodine from the soil. The content of iodine in the aboveground part of rice plants was 16 mg kg(-1) dry weight and the percentage of iodine transferred per cropping from the soil into the aboveground biomass corresponded to 0.27% (20 mg m(-2)) of the upper soil layer content.