试析空中水分对探空仪温度观测的影响

在气象温度测量过程中,空中水分会直接影响到温度测量数据,导致其失真进而降低气象探空温度观测工作效率,必须予以解决。因此本文就运用到了GTS1型探空仪技术,基于现代化、精细化技术内涵分别测试检验了两段空中水分对探空仪温度观测的实录片段,结合结果阐述测试检验结果有效性,包括空中水分对探空仪温度观测所产生的影响。

Spatial Distribution and Seasonal Variations of Heavy Metal Contamination in Surface Waters of Liaohe River, Northeast China

Heavy metal pollutants are a worldwide concern due to slow decomposition, biocondensation, and negative effects on human health. We investigated seasonal and spatial variations of the five heavy metals and evaluated their health risk in the Liaohe River, Northeast China. A total of 324 surface water samples collected from 2009 to 2010 were analyzed. Levels(high to low) of heavy metals in the Liaohe River were: zinc(Zn) > chromium(Cr) > copper(Cu) > cadmium(Cd) > mercury(Hg). Spatial and seasonal changes impacting concentrations of Cu and Zn were significant, but not significant for Cr, Cd and Hg. The highest concentrations of heavy metals were: Hg at Liuheqiao, Cu at Fudedian, Zn at Tongjiangkou, Cr at Mahushan, and Cd at Shenglitang. The highest concentrations of Hg and Cr were found in the wet period, Cu and Cd in the level period, and Zn in the dry period. The surface water of a tributary was an important accumulation site for heavy metals. Health risks from carcinogens and non-carcinogens increased from upstream to downstream in the mainstream of the Liaohe River. The total health risk for one person in the Liaohe River exceeded acceptable levels. The total health risk was the greatest during the wet period and least in the dry period. Among the five heavy metals in the Liaohe River, Cr posed the greatest single health risk.

Spatial distribution of penetration depth in Taihu Lake (China) during spring and autumn

In the context of remote sensing, sunlight penetration depth is the depth above which 90% of the diffusely reflected irradiance from a water body surface originates. Model algorithms to simulate water quality variables such as chlorophyll a, dissolved organic matter, suspended matter, and Secchi depth are sensitive to the variations of this variable. The penetration depth for Taihu Lake in China, a shallow and turbid lake, was calculated by using a multiple scattering model, and in situ optical measurements were carried out during May and October 2010. The results show that:1) the penetration depth generally increased from west to east during spring and from southeast to northwest during autumn, reflecting the prevailing wind direction and; 2) there was strong dependence of the penetration depth on the concentration of suspended matter.

Evaluation of hollow fiber T-type zeolite membrane modules for ethanol dehydration

This work presents the design of hollow fiber T-type zeolite membrane modules with different geometric configurations. The module performances were evaluated by pervaporation dehydration of ethanol/water mixtures. Strong concentration polarization was found for the modules with big membrane bundles. The concentration polarization was enhanced at high temperature due to the higher water permeation flux. The increase of feed flow could improve water permeation flux for the membrane modules with small membrane bundle.Computational fluid dynamics was used to visualize the flow field distribution inside of the modules with different configurations. The membrane module with seven bundles exhibited highest separation efficiency due to the uniform distribution of flow rate. The packing density could be 10 times higher than that of the tubular membrane module. The hollow fiber membrane module exhibited good stability for ethanol dehydration.

Spatio-temporal distribution of dissolved sulfide in China marginal seas

With sulfide increasingly recognized as an important parameter to assess the oxidation-reduction level in aqueous enviromnent, research on its geochemical behavior is becoming important. Water samples collected in Bohai Sea （1-19 August, 2010）, Yellow Sea （20-30 November, 2010） and East China Sea （3-17 June, 2010 and 1-10 November, 2010） were used to determine the occurrence and distribution of dissolved sulfide by methylene blue spectrophotometric method. Results show that： （1） horizontally, concentration of dissolved sulfide significantly varied from the coastal region to the open sea and profoundly influenced by physical processes. High values occurred in the river-sea boundary zone ＂marginal filter＂ due to rich riverine input, frequent upwelling and active exchange in shelf edge. Terrestrial input from adjacent rivers and the current cycling contributed to the high sulfide appeared in western Bohai Sea, eastern Shandong Peninsula, and northeast of Changjiang （Yangtze） River estuary. Especially, relative higher sulfide values occurred in Yellow Sea, which is consistent with the variation of salinity largely due to the hydrodynamic feature; （2） vertically, measurement of dissolved sulfide in bottom water was higher and more variable than that in surface water caused by the wind-induced resuspension and dissimilatory sulfate reduction. Moreover, nutrient-type profile clearly identified that oxidation plays a major role in the biogeochemistry cycle of sulfide in water; （3） seasonally, investigation for East China Sea in June and November reflected seasonal variation of Changjiang River Diluted Water, Kuroshio Current, and Taiwan Warm Current. Concentration in June was much higher than that sampled in November at most stations. Mean concentration of dissolved sulfide varied seasonally from 2.26 μg/L （June） to 1.16 μg/L （November） in surface and 3.00 μg/L （June） to 1.56 μg/L （November） in bottom. Progress in the field is slow and more effort is needed to ensure the accuracy and reliability of determination and estimate the natural or anthropogenic contribution of dissolved sulfide in ecosystems.

Temporal Variations in Soil CO_2 Efflux Under Diferent Land Use Types in the Black Soil Zone of Northeast China

The quantification of soil CO2 effiux is crucial for better understanding the interactions between driving variables and C losses from black soils in Northeast China and for assessing the function of black soil as a net source or sink of atmospheric CO2 depending upon land use. This study investigated responses of soil CO2 effiux variability to soil temperature interactions with different soil moisture levels under various land use types including grassland, bare land, and arable （maize, soybean, and wheat） land in the black soil zone of Northeast China. The soil CO2 effiuxes with and without live roots, defined as the total CO2 efftux （FtS） and the root-free CO2 ei^lux （FrfS）, respectively, were measured from April 2009 to May 2010 using a static closed chamber technique with gas chromatography. The seasonal soil CO2 fluxes tended to increase from the beginning of the measurements until they peaked in summer and then declined afterwards. The mean seasonal FtS ranged from 20.3=h7.8 to 58.1~21.3 mg CO2-C m-2 h-1 for all land use types and decreased in the order of soybean land ~ grassland 〉 maize land ~ wheat land ） bare land, while the corresponding values of FrfS were relatively lower, ranging from 20.3~7.8 to 42.3~21.3 mg CO2-C m-2 h-1. The annual cumulative FtS was in the range of 107-315 g CO2-C m-2 across all land uses types. The seasonM CO2 effiuxes were significantly （P 〈： 0.001） sensitive to soil temperature at 10 cm depth and were responsible for up to 62% of the CO2 effiux variability. Correspondingly, the temperature coefficient Q10 values varied from 2.1 to 4.5 for the seasonal FtS and 2.2 to 3.9 for the FrfS during the growing season. Soil temperature interacting with soil moisture accounted for a significant fraction of the CO2 flux variability for FtS （up to 61%） and FrfS （up to 67%） via a well-defined multiple regression model, indicating that temperature sensitivity of C02 flux can be mediated by water availability, especially under water stress.

Mapping paddy rice with multi-date moderate-resolution imaging spectroradiometer (MODIS) data in China

The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderate-resolution imaging spectroradiometer(MODIS) data in China.Paddy rice fields were extracted by identifying the unique char-acteristic of high soil moisture in the flooding and transplanting period with improved algorithms based on rice growth calendar regionalization.The characteristic could be reflected by the enhanced vegetation index(EVI) and the land surface water index(LSWI) derived from MODIS sensor data.Algorithms for single,early,and late rice identification were obtained from selected typical test sites.The algorithms could not only separate early rice and late rice planted in the same fields,but also reduce the uncertainties.The areal accuracy of the MODIS-derived results was validated by comparison with agricultural statistics,and the spatial matching was examined by ETM+(enhanced thematic mapper plus) images in a test region.Major factors that might cause errors,such as the coarse spatial resolution and noises in the MODIS data,were discussed.Although not suitable for monitoring the inter-annual variations due to some inevitable factors,the MODIS-derived results were useful for obtaining spatial distribution maps of paddy rice on a large scale,and they might provide reference for further studies.