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11.
12.
Global forest systems: An uncertain response to atmospheric pollutants and global climate change? 总被引:1,自引:0,他引:1
Forest systems cover more than 4.1×109 ha of the Earth's land area. The future response and feedbacks of forest systems to atmospheric pollutants and projected climate change may be significant. Boreal, temperate and tropical forest systems play a prominent role in carbon (C), nitrogen (N) and sulfur (S) biogeochemical cycles at regional and global scales. The timing and magnitude of future changes in forest systems will depend on environmental factors such as a changing global climate, an accumulation of CO2 in the atmosphere, and increase global mineralization of nutrients such as N and S. The interactive effects of all these factors on the world's forest regions are complex and not intuitively obvious and are likely to differ among geographic regions. Although the potential effects of some atmospheric pollutants on forest systems have been observed or simulated, large uncertainty exists in our ability to project future forest distribution, composition and productivity under transient or nontransient global climate change scenarios. The potential to manage and adapt forests to future global environmental conditions varies widely among nations. Mitigation practices, such as liming or fertilization to ameliorate excess NOx or SOx or forest management to sequester CO2 are now being applied in selected nations worldwide.The U.S. Government's right to a non-exclusive, royalty free licence in and to any copyright is acknowledged. 相似文献
13.
Sulfur in soils 总被引:4,自引:0,他引:4
Heinrich Wilhelm Scherer 《植物养料与土壤学杂志》2009,172(3):326-335
Sulfur (S) deficiency of crops, which has been reported with increasing frequency over the past two decades on a worldwide scale, is a factor that reduces yield and affects the quality of harvested products. Especially in Western European countries, incidence of S deficiency has increasingly been reported in Brassicaceae. For this reason, more attention should be paid to the optimization of S‐fertilizer application, in order to cover plant S requirements whilst minimizing environmental impacts. In soils, S exists in inorganic and organic forms. While sulfate (SO ), which is a direct S source for plants, contributes up to 5% of total soil S, generally more than 95% of soil S are organically bound. Organic S is divided into sulfate ester and carbon‐bonded S. Although not directly plant‐available, organically bound S may potentially contribute to the S supply of plants, especially in deficiency situations. Sulfur turnover involves both biochemical and biological mineralization. Biochemical mineralization, which is the release of SO from the ester sulfate pool through enzymatic hydrolysis, is controlled by S supply, while the biological mineralization is driven by the microbial need for organic C to provide energy. 相似文献
14.
ZHAO Yan-Wen J. D. BEATON CAO Zhi-Hong A. M. HENDERSON HU Zheng-Yi XU Cheng-Kai 《土壤圈》2001,11(1):63-66
A 40-day gnotobiotic microcosm experiment was carried out to quantify the effect of bacterial-feeding nematode on plat growth and nutrient absorption.The results showed that inoculation of bacterial-feeding nematode Protorhabditis sp.stimulated the growth of wheat (Triticum aestivum) and the uptake of N.By the end of the 40-day incubation wheat biomass and N uptake in the treatment with nematode and bacteria (Pseudomonas sp.)increased by 6.5% and 5.9%,respectively,compared with bacteria alone treatment.The presence of nematode mainly accelerated the growth of aboveground of wheat,while it slightly inhibited the root development.There was little difference in plant tissue N concentration between treatments.P concentration and uptake of wheat,however,were generally reduced by nematode, It appears that the enhancement of plant growth and nitrogen uptake is attributed to the enhancement of nitrogen mineraliztion induced by nematode feeding on bacteria,and the reduction of phosphorous uptake is the result of ewak root status and comptetition by bacteria immobilzation. 相似文献
15.
《Communications in Soil Science and Plant Analysis》2012,43(1):79-86
Abstract The bismuth sulfide and methylene blue colorimetric finishes for soil sulfate determination by the Johnson‐Nishita distillation method were examined and compared. Both procedures gave comparable results when applied to soils and soil extracts, but the bismuth method was more rapid and more reliable. Nitrogen flow rate over the range 100–500 ml/min was not critical for the bismuth method, provided appropriate distillation times were employed. However, the release and transfer of hydrogen sulfide in the bismuth method was effected in one‐third of the time required for the méthylène blue finish, largely due to the elimination of a gas‐washing step. Predrying of soil extract samples increased recovery of hydrogen sulfide with the bismuth procedure arid could be used to increase sensitivity. Nitrate interference was observed with the bismuth procedure but attributed to interference during the reduction step. The bismuth procedure can readily be adapted for microdetermination in the 0–40 ppm sulfate‐S range. 相似文献
16.
《Communications in Soil Science and Plant Analysis》2012,43(3):257-266
Abstract Procedures for S determination involving digestion of plant material with HNO3/HClO4 mixtures gave lower values than those using oxygen flask combustion. Tests on a range of S compounds showed that the HNO3/HClO4 procedure underestimated S present in methionine, cysteine and glutathione but S in sulfate and the glucosinolate, sinigrin, was not underestimated. Low recoveries using HNO3/HClO4 digestion procedures can be due both to incomplete oxidation of certain compounds and to gaseous losses during the vigorous boiling stage of digestion. 相似文献
17.
《Journal Of Aquatic Food Product Technology》2013,22(4):23-34
Abstract Lightly salted lumpfish roe (3.5–4.8% fw/w] salt in the water-phase, pH 5.4, vacuum-packed) was stored at 5°C. After 2 1/2 or 3 months of storage, different degrees of spoilage, caused by bacterial activity, occurred in eleven roe batches. Off-odors ranged from no or very weak odors to strong sulphury, sour odors. The microflora consisted of lactic acid bacteria, Enterobacteriaceae and Vibrio spp. Concentration of lactic acid, acetic acid, trimethylamine and total volatile bases were unrelated to spoilage odors. Volatile sulfur compounds (H2S, probably CS2, CH3SH and CH3CH2SH or CH3SCH3), produced during storage, appeared to be contributors to spoilage odors. 相似文献
18.
不同品种硫肥对苋菜镉累积的影响 总被引:3,自引:0,他引:3
为选择适宜种类的硫肥来辅助苋菜修复土壤Cd污染,采用盆栽试验,以苋菜(Amaranshus mangostanus L.)为供试作物,在两种酸性土壤(黄棕壤、赤红壤)上施用硫磺、硫酸钙、硫酸铵三种不同硫肥,探究不同特性硫肥对酸性土壤上苋菜生长及其对硫和Cd的吸收以及累积的影响。结果显示,两种酸性土壤中施用硫肥均促进了苋菜植株对硫的吸收,且减轻了Cd对植株的毒害作用,苋菜的生物量显著提高。此外,三种不同特性硫肥施入两种Cd污染的土壤,苋菜地上和地下部Cd含量均显著增加。两种酸性土壤施用不同硫肥后,苋菜硫和Cd累积量增加,其中以施加硫酸铵效果最佳;黄棕壤和赤红壤中苋菜地上部Cd累积量分别比对照高1.45倍和2.39倍;施加硫磺后苋菜根部Cd累积量最少。硫酸铵作为含氮硫肥在黄棕壤和赤红壤上施用,可有效辅助苋菜修复土壤Cd污染。 相似文献
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20.
为了研究SO2对昆虫天敌的影响,本试验采用单体和群体饲养的方法研究了0(ck) 、855、1995、3990和5700 mg/m3 5个SO2浓度处理对异色瓢虫[Harmonia axyridis(Pallas)]的生长发育和体内保护酶的影响.结果表明:各个不同浓度的SO2都能促进异色瓢虫幼虫的发育进度,提高幼虫的体重... 相似文献