Emission of CO2, CH4 and N2O from freshwater marsh in northeast of China.

The wetlands play an important role in carbon storage, especially at high latitudes, at which they store nearly one-third of global soil carbons. However, few studies have investigated the emissions of CO(2), CH(4) and N(2)O in the long-term, especially effects of freeze-thaw cycles on these gases emissions in freshwater marsh ecosystems. In this paper, we collected greenhouse gas emission data from a freshwater marsh area in China for 4 years, evaluated their release variables and speculated on their potential atmospheric impact.

Mercury contamination and health risk to crops around the zinc smelting plant in Huludao City, northeastern China.

The Huludao zinc plant in Liaoning province, northeast China was the largest in Asia, and its smelting activities had seriously contaminated soil, water and atmosphere in the surrounding area. For the first time, we investigated the total mercury (THg) content in maize, soybean, broomcorn, 22 vegetables, and the soil around their roots from eight sampling plots near the Huludao zinc plant. THg contents of the seeds of maize, soybean, and broomcorn are 0.

[Nitrification-denitrification and N2O emission of typical Calamagrostis angustifolia wetland soils in Sanjiang plain].

With intact soil core and by using acetylene inhibition method, this paper measured the N2O emission and denitrification rates of typical Calamagrostis angustifolia wetland soils in Sanjiang Plain, analyzed their relationships with environmental factors, and estimated the total amounts of N2O emission and denitrification loss. The results showed that meadow marsh soil and humus marsh soil had a similar change range of N2O emission rate (0.020-0.

Sandy desertification change and its driving forces in western Jilin Province, North China.

This paper investigates the sandy desertification change between 1986 and 2000 in the western Jilin province, North China. Land use and land cover data were obtained from Landsat TM data by using a supervised classification approach. We summarized the total area of desertified land by each county, as well as the area for each of the four categories of desertified land.

[Dynamics of H2S and COS emission fluxes from Calamagrostis different calamagrostis angustifolia wetlands in Sanjiang Plain].

Using the static chamber and chromatogram method, H2S and COS emission fluxes from the mash meadow Calamagrostis angustifolia in Sanjiang Plain were measured during growth season(5-9 month), the results showed that the seasonal and diurnal variations of H2S and COS emission fluxes were obvious, the mean H2S and COS emission fluxes from the mash meadow Calamagrostis angustifolia were 0.34 microg x (m2 x h)(-1) and - 0.29 microg x (m2 x h)(-1) respectively, the Calamagrostis angustifolia wetlands were the sources for H2S and the sinks for COS during the growth time.

[Annual dynamics of CO2, CH4, N2O emissions from freshwater marshes and affected by nitrogen fertilization].

Annual dynamics of CO2, CH4, N2O emissions from freshwater marshes and affected by nitrogen fertilization were studied in situ in Sanjiang Plain of Northeast China from June 2002 to December 2004, using the static opaque chamber-GC techniques. The results showed that there was significant seasonal and annual variation in the CO2, CH4 and N2O emissions. The ecosystem emission of CO2 reached a maximum of 779.

[Spatial distribution of Cd, Pb, as contents in the farmland black soil in Jilin Province].

Spatial distribution and pattern of Cadmium (Cd), Lead (Pb) and Arsenic (As) contents in the farmland black soil in Jilin Province were analyzed using geostatistics methods. Result of semivariance fitness models showed that Pb content in soil was auto-correlated to a moderate degree while contents of Cd and As were auto-correlated to a low degree, respectively. Based on the results of semivariance analyses, distribution maps were generated using Kriging interpolation.

[Phytoavailable lead in rhizosphere of lettuce].

A greenhouse experiment was performed to investigate the influence of pH TOC, and fractionation of Pb on phytoavailability of Pb in the rhizosphere of lettuce. And the Low molecular-weight organic acids (LMWOAs) were used to evaluate the phytoavailability of soil Pb to lettuce. The results show that the pH is lower in the rhizosphere compared to the bulk soil, and the rhizosphere becomes more acidic with increasing Pb (NO3)2 applied.

Assessment of chlorophyll-a concentration and trophic state for Lake Chagan using Landsat TM and field spectral data.

In this study, we present the digital evaluation of Landsat TM data and field spectral measurements for retrieving chlorophyll-a (chl-a) concentration and trophic state index in Lake Chagan of Northeast China. Chl-a concentration of the lake can be estimated from the band ratio (TM4/TM3) and the field spectral data at 670 nm (absorption peak) and at 700 nm (reflectance peak). The results show that the best determination coefficient (R (2)) is 0.

[Effects of nitrogen fertilization on carbon balance in the freshwater marshes].

To understand the influence of nitrogen fertilization on the carbon balance in the freshwater marshes, we measured the CO2 and CH4 emissions as well as net ecosystem exchange (NEE) of CO2 using the static chamber and gas chromatogram technique in situ over Deyeuxia angustifolia wetland in Sanjiang Plain. Results from the field observed indicated that fertilization increased the biomass and gross primary productivity (GPP) as well as the CO2 and CH4 emissions, while decreased the net ecosystem exchange of CO2 but not change the seasonal dynamics of CO2 and CH4 emissions as well as the NEE. Seasonal amount of CO2 and CH4 emission from the fertilization was respectively 34% and 145 % higher than that from the control, while the NEE and net carbon exchange decreased 70% and 81.

[Responses of soil temperature in wetland ecosystem to air temperature and their effects on CO2 emission].

Through two years located field observation, this paper studied the responses of marsh soil temperature to air temperature and the effects of soil temperature on CO2 emission from marsh soil-vegetation system, and calculated the seasonal variation of CO2 emission. The results showed that from the beginning of thawing, an increasing trend of soil temperature was exerted by the change of air temperature, and there was a significant exponential correlation between soil temperature in root layer and air temperature (R2 = 0.94, P<0.

Assessment of soil lead exposure in children in Shenyang, China.

Soil lead pollution is serious in Shenyang, China. The paper brings together the soil work, the bioaccessibility, and the blood lead data to assess the soil lead exposure in children in Shenyang, China. Approximately 15.

[Structural characteristics of soil nematodes community under different land uses in Changchun City].

In this paper, an investigation on the species richness and abundance of soil nematodes in farmland, natural secondary forest, shelter forest and green space was made in Changchun City in July and September, 2003. Soil nematodes were extracted with Baermann extractor, and identified to the genus level with the aid of microscope. A total of 7273 soil nematode individuals were captured, and fell into 2 classes, 7 orders, 20 families, and 27 genera.

[Adaptability of Litopenaeus vannamei to saline-alkali water in west Jilin Province].

By supplementing natural saline-alkali water into desalinated prawn-cultivating pond, this paper studied the survival ability of Litopenaeus vannamei under saline-alkali water environment. The results showed that the survival duration of untamed juvenile shrimp was more than 96 hours at the alkalinity of saline-alkali water from 5.15 to 19.

[Biomass structure and nitrogen and phosphorus contents of Calamagrostis angustifolia populations in different communities of Sanjiang Plain].

Calamagrostis angustifolia is the dominant species in the typical meadow and marsh meadow communities of Sanjiang Plain. The study on its biomass structure and the N and P contents in its different organs showed that the biomass of different C. angustifolia organs in the two types of wetland communities was distinctly different, which could be described by Y = A + B1t + B2t2 + B3t3.

[Dynamics of dissolved organic carbon (DOC) leaching in meadow marsh soil and related affecting factors].

In this paper, an incubation test with soil columns was carried out for 35 days to study the dynamics of DOC leaching from the organic layers (2 approximately 13 cm) of two meadow marsh soils, and the correlation of DOC release with soil respiration, NH4+ formation, and leachate pH. The results showed that in the first week, DOC release presented a fast decrease, and then held on a steady level, which could be well described by one order exponential equation (R2 > 0.96, P < 0.

Distribution patterns of lead in urban soil and dust in Shenyang city, Northeast China.

We investigated the spatial distribution of Pb in soil and dust samples collected from 54 sites in Shenyang city, Liaoning province, Northeast China. Soil background Pb concentration was 22 mg kg(-1) and control values from non-industrial areas were 33 mg kg(-1) for soil and 38 mg kg(-1) for dust. Soil Pb concentrations varied widely, ranging from 26 to 2911 mg kg(-1), with a mean concentration of 200 mg kg(-1), 9 times the background value and 6 times the control value.

Preliminary study on health risk from mercury exposure to residents of Wujiazhan town on the Di'er Songhua river, Northeast China.

Mercury concentrations in hair are typically used as a biomarker to assess exposure to mercury. A total of 108 hair samples were collected from residents (age range 5-73 years) of Wujiazhan town, northeast China, to determine total mercury concentrations. Hair mercury concentrations ranged from 0.

[Influence of soil lead upon children blood lead in Shenyang City].

The dynamic correlation coefficients between soil lead and blood lead, the children blood lead arose from soil lead and the length of time over which the blood lead concentration can fall to be at or below the threshold value (10 microg x dL(-1)) are analyzed. If the aggregated soil lead and blood lead are stratified by the seven geographic regions studied, an elevated R of 0.9200 could be calculated, and the lead exposure assessment may require knowledge of geographic dimension of the exposure topology components.

Changes of land use and of ecosystem service values in Sanjiang Plain, Northeast China.

Agricultural activities, especially reclamation, are considered major threats to the wetland ecosystems in Sanjiang Plain, the largest concentrated area of the freshwater wetlands in China. In the past decades, the area of the cultivated land and its grain production have been increased at the cost of wetlands shrinkage. The large-scale land reclamation severely affected the ecosystems in this region.

A model supported by GIS for locating and quantifying PM2.5 emission originated from residential wood burning.

A research method was presented for spatially quantifying and allocating the potential activity of a fine particle matter emission (PM2.5), which originated from residential wood burning (RWB) in this study. Demographic, hypsographic, climatic and topographic data were compiled and processed within a geographic information system (GIS), and as independent variables put into a linear regression model for describing spatial distribution of the potential activity of residential wood burning as primary heating source.

[Dynamics of CO2, CH4 and N2O emission fluxes from mires during freezing and thawing season].

In the Sanjiang Plain, the freezing and thawing phase have 7 - 8 months and play important role in the greenhouse gases emission. The characters of the greenhouse gases emission during freezing and thawing season in the Sanjiang Plain were studied, using the static chamber and gas chromatogram method. The results observed show that there were obvious CH4 and CO2 emissions in winter and the CH4 emission made a relatively large contribution to the total CH4 flux from the different type mires during the winter in the Sanjiang Plain.

[Redistribution patterns of black soil in hillslope landform of Northeast China: a 137Cs study].

In the black soil region of Northeast China, soil and water loss is quite serious, but not fully investigated due to the lack of reliable methods. 137Cs technology is a good one to study the medium-and long term erosion and sedimentation rates and the spatial redistribution of soil. With this technology and the existing calibration models, this paper studied the redistribution patterns of black soil in a typical hillslope landform of Northeast China.

Cold season CH4, CO2 and N2O fluxes from freshwater marshes in northeast China.

Cold season (winter and thaw) CH4, CO2 and N2O fluxes from freshwater marshes (47 degrees 35'N, 133 degrees 31'E, Northeast China) were measured, using the static chamber method. The mean CH4 and CO2 fluxes from Carex lasiocarpa (Cl) were 0.5+/-0.

[Variation of soil temperature before and after cultivation of marsh and its effect on soil thermal regime].

Marsh has important ecological and environmental functions and is sensitive to the global climate change, while the variation of soil temperature could better indicate the climate fluctuation. Our study showed that the annual and seasonal dynamic changes of soil temperature in marsh showed distinctly "sinusoid" character curve, whereas the mean annual temperature of different soil depths showed "U" feature. From May to September, the mean temperature at the topsoil (10 cm) of uncultivated marsh was 11.