钾和湿度对油菜生长及其营养吸收的影响

The Interaction between potassium and moisture during the growth of and nutrient uptake by rapeseed plats grown on K-deficient soils has been investigated in this study.The results show that the dry weight of the above-ground parts of the plant appears to be somewhat reduced when the volume water content of the soil remains 0.15 for 3 successive days.As the shortage in the soil water continues,the weight of the plant root and the permeability of the root plasmalemma are markedly affected;the stem thickness and leaf area are reduced.However,K application can increase the dry matter weight of the above-ground parts,the thickness of the stem,and the area of the leaf.Application of K can also maintain a comparatively low water potential(ψ)and a comparatively high moisture content in the leaves,thus increasing the drought-resisting ability of the plant.When the volume water content of the soil is raised to 0.30,leaf yellowing as a symptom of nutrient deficiency appears on rapeseed plants grown on K-deficient soils.With increase in soil moisture content,the Ca concentration of the aerial parts of the rapeseed plant without K application increases while the K concentration decreases,Both K application and the soil moisture regime have very little effect on the Mg Concentration in the plant.Under soil mosture stress,the nitrogen content and total amount of amino acids in rape leaves increases;and thus more proline and glutamic acid is formed.On the other hand,the impact of soil moisture on pant‘s dry matter is governed by the status of potassium nutrition.On soils with low K.the moisture content has very little effect on yield;when K fertilizer is applied,however,the moisture content shows a very significant effect on yield increase.     

DEHP污染的两种土壤中接种丛枝菌根对豇豆生长和DEHP降解的影响

A 60-day pot experiment was carried out using di-(2-ethylhexyl) phthalate (DEHP) as a typical organic pollutant phthalic ester and cowpea (Vigna sinensis) as the host plant to determine the effect of arbuscular mycorrhizal inoculation on plant growth and degradation of DEHP in two contaminated soils, a yellow-brown soil and a red soil. The air-dried soils were uniformly sprayed with different concentrations of DEHP, inoculated or left uninoculated with an arbuscular mycorrhizal (AM) fungus, and planted with cowpea seeds. After 60 days the positive impact of AM inoculation on the growth of cowpea was more pronounced in the red soil than in the yellow-brown soil, with significantly higher (P < 0.01) mycorrhizal colonization rate, shoot dry weight and total P content in shoot tissues for the red soil. Both in the yellow-brown and red soils, AM inoculation significantly (P < 0.01) reduced shoot DEHP content, implying that AM inoculation could inhibit the uptake and translocation of DEHP from roots to the aboveground parts. However, with AM inoculation no positive contribution to the degradation of DEHP was found.     

湿沉淀对采汞地区山地土壤中汞的影响

There is abundance of Mercury mine resurces in the Fanjinshan Mountain,Mining mercury has a long history there,The concentration of geseous Hg produced in smelting He reaches 20-50mg/m^3 in the tail gas.Because mercury element is an easily transferring microelement,the paper talks about the effect of mercury in Hg mining in Guizhou Province on alpine soil,analyses Hg content in alpine soil at 2000 m of relative elevation in the Hg mining area,and explores for causes of the Hg pollution.     

酸沉降区土壤－作物系统的汞污染

In acid precipitation area of Chongqing suburb the average of Hg in soil rose from 0.158mg/kg in 1984 to 0.20mg/kg in 1989,and Hg content of crops grown on these soils increased too.Both soil and vegetable Hg came mainly from power plant emission.which caused Hg and acid precipitiation pollution in environment and the Hg pollution of water,crops and milk in the area.     

14C标记秸秆碳素在老成土和变性土中的转化

Hg vertial transference in soil-water system was studied by analyzing Hg vertical ditribution in soil column after adding Hg and one of the two leacheates,deionzied water or acid rain,into soil column.The results indicated that Hg was hardly transferable in puple soil.About 86%-88% of the total soil Hg was distributed in the top layer (0-2cm) and to Hg was detected in the leakage when the purple soil column was leached by deionized water and simulated acid rain.But Hg was more movalbe in yellow soil with only about 20%-22% of the total soil Hg distributed in the top layer (0-2cm),and about 17%-25% washed out from the soil column by deionized water and simulted acid rain,Incremant in soil bulk density colud reduce Hg leaching,thus the more the Hg kept in soil,the less the Hg leached into underground water,Deionized water and acid rain almost played the same role in leaching Hg.Bentioint was most effecient in preventing Hg from vertcal transferring in the soil coulumn.     

内蒙古荒漠化草地土壤碳、氮养分及土壤呼吸的空间异质性研究

There is a limited knowledge of spatial heterogeneity in soil nutrients and soil respiration in the semi-arid and arid grasslands of China. This study investigated the spatial differences in soil nutrients and soil respiration among three desertified grasslands and within two shrub-dominated communities on the Ordos Plateau of Inner Mongolia, China in 2006. Both soil organic carbon (SOC) and total nitrogen (TN) were significantly different (P < 0.01) among the three desertified grasslands along a degradation gradient. Within the two shrub-dominated communities, the SOC and TN contents decreased with increasing distance from the main stems of the shrub, and this “fertile island” effect was most pronounced in the surface soil. The total soil respirations during the growing season were 131.26, 95.95, and 118.66 g C m-2, respectively, for the steppe, shrub, and shrub-perennial grass communities. The coefficient of variability of soil respiration was the highest in the shrub community and lowest in the steppe community. CO2 effluxes from the soil under the canopy of shrub were significantly higher than those from the soil covered with biological crusts and the bare soil in the interplant spaces in the shrub community. However, soil respiration beneath the shrubs was not different from that of the soil in the inter-shrub of the shrub-perennial grass community. This is probably due to the smaller shrub size. In the two shrub-dominated communities, spatial variability in soil respiration was found to depend on soil water content and C:N ratio.     

不同湿度条件下与植物残茬共培养的土壤中的低分子量脂肪酸

Iucubation experiments were conducted to investigate the dynamics of low-molecular-weight aliphatic acids i two andosols with and without plant materials.Results showed that amount of low-molecular-weight aliphatic acids in soils alone varied considerably with water regime under which the soil was incubated,duration of incubation and soil organic matter content,ranging from 257-860μmol kg^-1 soil,of which 19%-33% was in free state.Incorporation of plant matrials increased greatly both the amount and unmber of members of low-molecular-weight aliphatic acids,and also the proportion of low-molecular-weght aliphatic acids occurred in free state ,Generally,among these ,aliphatic acids detected,acetic,propionic,glyoxalic and formic acids were predominant.     

山地自然保护区垂直带植物铅含量特征

Typical plants and soils of four elevation zones, mountain tundra （Zone A）, Betula ermanii forest （Zone B）, mountain dark coniferous forest （Zone C）, and mountain coniferous and broad-leaf forest （Zone D）, along the vertical gradient of the northern mountain slope of the Changbai Mountain National Nature Reserve, Jilin Province, China, were sampled to study the relationship between plant and soil Pb, and to compare the Pb levels in typical plant types within the same elevation zone. The Pb contents in the soil and plant samples were measured by using a flame atomic absorption spectrophotometer. The results showed that the average plant Pb contents of the four plant elevation zones were lower than the average worldwide level, except for Zone B. Compared with the average level in China or the average worldwide level, the soil Pb levels of the four plant zones were higher, with Zones D and B having the lowest and highest averages, respectively. Plant Pb levels fluctuated from the upper to the lower zones, in a pattern of low-high-low-high, which was the same as that of the soils in the four zones. Furthermore, plant Pb was closely related to soil Pb. Depending on the plant species and plant parts, large differences were found in the Pb levels of typical plants within each zone. In Zone A, Vaccinium uliginosum and Rhododendron redowskianum had higher Pb levels than the other plants. In Zone C, the Pb levels in the branches of both plant species were higher than those in the leaves, which was contrary to Zone D. In Zone B, the Pb levels in the plant parts varied greatly with plant species.     

AM真菌群落改善保护地退化土壤质量和黄瓜生长的效应

A pot experiment was performed to determine the effects of arbuscular mycorrhizal fungi(AMF) communities on soil properties and the growth of cucumber seedlings in a degraded soil that had been used for continuous cucumber monoculture in a greenhouse for 15 years.In the experiment,AMF communities(created by combining various AMF species that were found to be dominant in natural farm soil) were inoculated into the degraded soil,and then the soil was planted with cucumber.Inoculation with AMF communities did not affect soil pH but increased soil aggregate stability and decreased the concentrations of salt ions and electrical conductivity(EC) in the soil.Inoculation with AMF communities increased the numbers of culturable bacteria and actinomycetes but reduced the number of fungi.AMF communities increased plant growth,soluble sugar content,chlorophyll content,and root activity compared to non-mycorrhizal or a single AMF species treatments.Improvements of soil quality and plant growth were greatest with the following two communities:Glomus etunicatum + G.mosseae + Gigaspora margarita + Acaulospora lacunosa and G.aggregatum + G.etunicatum + G.mosseae + G.versiforme + G.margarita + A.lacunosa.The results suggested that certain AMF communities could substantially improve the quality of degraded soil.     

中国湖南省主要水稻土类型的氨固定

The contents, affecting factors, seasonal changes and availability of fixed ammonium in major types ofpaddy soils derived from different parent materials in Hunan Province, China, were studied using the Silva-Bremner method by laboratory and pot experiments. Results showed that the content of fixed ammoniumin the plough horizons ranged from 88.3 mg kg-1 to 388.1 mg kg-1, with 273.2 ± 77.7 mg kg-1 on average,accounting for 11.2% of total soil N on average. Content of fixed ammonium decreased in the order of newlylacustrine clayey paddy soil ＞ alluvial sandy paddy soil ＞ purple clayey paddy soil ＞ newly alluvial sandypaddy soil ＞ yellow clayey paddy soil ＞ reddish-yellow clayey paddy soil ＞ granitic sandy paddy soil. Therewere four distribution patterns of fixed ammonium in the profiles to 1-m depth, i.e., increase with the depth,decrease with increasing depth, no distinct change with the depth, and abrupt increase or decrease in somehorizon. Percentage of fixed ammonium in total N increased with the depth in most of the soils. Fixationof NH4+ by soil was higher at 30 ℃ than at 20 ℃ and 40 ℃, and continuous submergence benefited thefixation of NH4+ in newly alluvial sandy paddy soil, purple clayey paddy soil and alluvial sandy paddy soil,while alternating wetting and drying contributed to the fixation of NH4+ in yellow clayey paddy soil mostly.Fixed ammonium content in the test paddy soils was significantly correlated with ＜ 0.01 mm clay content(P ＜ 0.05), but not with ＜ 0.001 mm clay content, total N, organic N and organic matter. Fixed ammoniumcontent varied with rice growth stages. Application of N fertilizer promoted fixation of NH4+ by soil, and Nuptake by rice plant promoted release of fixed ammonium from the soil. Recently fixed ammonium in paddysoil after N fertilizer application was nearly 100% available to rice plant, while native fixed ammonium wasonly partly available, varying with the soil type and rice type.     

利用 DMA-80 直接测汞仪测定植物样品中总汞含量

为建立采用 DMA-80 直接测汞仪测定植物样品中汞含量的方法,配制了 3 种不同汞浓度系列的标准曲线,汞总量分别是 0 ～ 2、0 ～ 15 和 25 ～ 1023 ng。结果表明:仪器信号值与汞总量之间均呈良好的线性关系。同一样品进样 6 组平行测定,相对标准偏差小于 7%。根据仪器多次测定空白数据结果,按照称样量 0.1 g 计算,方法最小检出量为 0.169 ng/g;对不同样品添加同一质量的汞,每组 6 次重复,加标回收率为 99.3% ～ 102.2%,选取大米粉和柑橘叶两种国家标准物质进行测试,每个样品平行测定 6 次,其相对标准偏差均小于 7.0%,测定值与标准物质的标准参考值相符。利用 DMA-80 测汞仪测定植物样品中汞含量,无需前处理消煮,直接将样品送入仪器中,具有操作简单、快速高效等优点,精密度和准确度满足要求,可用于批量植物样品中汞含量的快速测定分析。     

An update of the mercury inventory and atmospheric mercury fluxes to and from Finland

Finland, the northern-most agricultural/industrial country in the world, has been for some time steadily improving environmental mercury (Hg) research. This paper focuses upon Hg recovery during zinc production, uses of Hg, updating of information on Hg emissions and atmospheric transport of Hg to and from Finland. The recovery of Hg as a by-product of zinc production began in 1970. The highest amount of recovered Hg was noted to be 160 t in 1989. Total uses of Hg in different sectors were about 7.4 t in 1992, which had decreased by 50% since the year 1987. In 1992, the estimated Hg emission to air was 2 t yr^?1, whereas to water and land the emission was about 0.20 and 3.67 t yr^?1, respectively. Natural Hg emission in Finland was estimated to be about 0.4 t yr^?1 (range: 0.3 to 0.5 t yr^?1). In addition, an initial attempt was made to estimate the atmospheric Hg flux to and from Finland; these values were noted to be 2.7 and 2.1 t yr^?1, respectively.     

Anthropogenic mercury emission in Europe

Preliminary estimates of Hg emissions from anthropogenic sources in Europe have been prepared to meet the request of air pollution transport modeling. Major emphasis was placed on four source categories: 1) combustion of fossil fuels, 2) non-ferrous metal production, 3) waste related sources, and 4) chlor-alkali production. Three chemical species: elemental, bivalent and particulate Hg were considered in these estimates. The emission estimates were spatially distributed within the EMEP grid of 150 km × 150 km for the year 1982.     

The phytotoxicity of mercury vapor

Seed germination and early growth were unexpectedly resistant to Hg-vapor at air saturation levels (14 μg L^?1). Among 15 species and cultivars tested, inhibition of shoot or root growth in excess of 50% was not seen, but occasional stimulation was noted. During extended (70 to 75 days) cultivation at Hg-vapor saturation, inhibitory effects on growth increased with time, and later effects on abscission and necrosis were more severe. Seven days exposures confirmed juvenile resistance at air saturation levels and mature plant sensitivity, expressed by massive abscission at 0.05 μg L^?1. It is suggested that Hg-vapor accelerates senescence-related processes via elevated ethylene production. Evidence suggests that elemental Hg, not ionic Hg, is the active toxicant. An ecophysiological role for Hg-vapor in volcanically active regions is suggested.     

Time resolution of mercury dose and lake sensitivity related to mercury content in fish

This work treats data from 75 small, mainly oligotrophic Swedish forest lakes. The aim is to study and evaluate the temporal variation of different Hg-dose and lake sensitivity parameters vs. Hg in 1-kg pike and small perch (<10 g). The lakes were treated with different remedies (such as lake liming) during 1987 in order to reduce Hg-levels in fish. Lake water chemistry has a large seasonal variation but the yearly means is clearly affected by the treatments (mean alkalinity is increased from 0.05 to 0.19 mcq^*L⁻¹). There is a marked change of Hg in perch 2 yr after treatment; the median decrease is 33%, a further time delay of about 2 yr is suggested for Hg in pike. Among the dose parameters, Hg in material from sediment traps and in water the fraction RIHg seem to be affected by the remedies with an accentuated decrease during 1988, while a slight increase of total-Hg (THg) in water can be observed. A regression model where the Hg content in perch (Hg-pe) is predicted by Hg-dose, pH and lake water retention time is presented (r²=0.71, n=22) as an example of the importance of using time compatible data with respect to the effect parameter (Hg-pe).     

Bioaccumulation of mercury and methylmercury

The factors controlling the accumulation of mercury in fish are poorly understood. The oft invoked lipid solubility of MMHg is an inadequate explanation because inorganic Hg complexes, which are not bioaccumulated, are as lipid soluble as their MMHg analogs and, unlike other hydrophobic compounds, MMHg in fish resides in protein rather than fat tissue. We show that passive uptake of the lipophilic complexes (primarily HgCl₂ and CH₃HgCl) results in high concentrations of both inorganic and MMHg in phytoplankton. However, differences in partitioning within phytoplankton cells between inorganic mercury — which is principally membrane bound — and MMHg — which accumulates in the cytoplasm — lead to a greater assimilation of MMHg during Zooplankton grazing. Most of the discrimination between inorganic and MMHg thus occurs during trophic transfer while the major enrichment factor is between water and phytoplankton. As a result, MMHg concentrations in fish are ultimately determined by water chemistry which controls MMHg speciation and uptake at the base of the food chain.     

Automated mercury determination in waters

A rapid technique for dissolved Hg determination in water at ultra-trace level is described. It consists of the automatisation of the cold-vapor/gold amalgamation/atomic fluorescence technique, which allows the determination of 8 samples per hour with an analytical precision of 5 % and a 0.1 ng.l^?1 detection limit for a 45 ml sample. It is suitable for Hg determination in most of the natural waters.     

Retention of mercury by soils

During the past one and a half decades there has been a marked increase in the total amount of mercury applied to the crop for control of agricultural pests particularly rice blight. It seems likely that the accumulation of mercury in agricultural products and soils has been increased. FURUTANI and OSAJIMA (3.4.5) investigated the content of mercury in rice, fruits, and vegetables and inferred that the mercury in fond products is partly the residue of fungicides sprayed on crops, and partly due to absorption from the soil by plant roots.