不同基因型玉米硫素吸收利用差异研究Ⅰ.根系吸收动力学参数与品种对硫肥的响应

应用同位素示踪技术,测定了34个不同基因型玉米水培幼苗根系对硫素的吸收动力学参数,大田试验调查了参试基因型在不同硫肥处理后的籽粒产量表现,测定了植株硫素吸收总量.结果发现不同基因型玉米对硫肥的反应存在很大的差异,而苗期根系的硫素吸收动力学参数与该品种施用硫肥后硫素吸收总量和籽粒产量的变化有密切联系,可以作为     

Reduction processes in forest wetlands: Tracking down heterogeneity of source/sink functions with a combination of methods

Wetlands are considered to be the biggest unknowns regarding the influence of global climate change on element dynamics, so knowledge of processes and conditions controlling sink and source functions of redox processes is crucial. The aim of this study was to investigate the sink/source function of nitrate, Fe, sulfate reduction and methanogenesis of an upland and a lowland fen within a boreal spruce catchment, southern Germany. We used suction cups and anaerobic dialysis chambers for soil solution sampling, FeS probes for the determination of S oxidation potential and stability of anoxic conditions and analysis of the soil solid phase (contents of C, S and Fe species). Both fens had high rates of nitrate reduction and potentially high rates of CH₄ production. The upper few cm of all profiles were oxic with low CH₄ concentrations, suggesting low CH₄ emission rates from the soil, though emission by vascular plants cannot be excluded. Sulfate and Fe reduction processes differed significantly in the fens. The upland fen was characterized by relatively stable anoxic conditions, low Fe contents but high contents of organic S and low C/S ratios. We concluded that the upland fen is an effective sink for sulfate with long-term S storage. In contrast, the lowland fen was characterized by alternating oxidation-reduction cycles with high Fe contents, lower contents of organic S and higher C/S ratios. Thus, even though low sulfate and high Fe concentrations in soil solutions indicated high reduction rates in the lowland fen, long-term storage of S is not likely in this fen. Differences in biogeochemical processes between sites are most likely not associated with hydrology but rather with the role of vascular plants.     

离子色谱法和毛细管电泳法测定土壤中氯离子、 硫酸根及其差异性

分别采用离子色谱法(IC)、毛细管电泳法(CE)两种仪器方法对不同pH土壤中Cl~–、SO_4~(2–)含量进行测定,并对其结果进行差异性分析。结果显示:参照标准物质的参考值(滴定法),IC与CE测定值的准确度、回收率均满足实验分析要求,但精密度差异较大,IC(RSD,3.61%)的稳定性优于CE(RSD,8.97%)。据差异性(F与t检验)分析,两种仪器方法测定酸性土壤中Cl~–、SO_4~(2–)含量存在显著性差异,而碱性、中性土壤的测定结果保持一致。对比4个被测样品基本性质发现,酸性土壤的pH与离子强度均低于其他样品,从而影响了石英毛细管的电渗流,最终改变了CE分离过程,这可能是Cl~–结果偏离的主要因素。同时,对于IC,酸性土壤较中性、碱性土壤更易由于离子交换效应产生次级保留(拖尾)。此外,采用碱性分离体系分离酸性样品易形成结晶,从而导致SO_4~(2–)含量的偏离。可见,两种方法各有优缺点。但是,IC较经典,而CE是一种新兴的仪器方法。测定像土壤这样基体较复杂的样品(特别是酸性土壤)中阴离子的仪器条件还需要进行更多摸索与优化,以促进这两种方法在土壤领域的推广与应用。     

A130 years deposition record of sulfate,nitrate and chloride from a high-alpine glacier

An ice core from a high-alpine glacier (Grenzgletscher, Colle Gnifetti, Monte Rosa massif, 4450 m a.s.l., Switzerland) was used to reconstruct the pollution history of Central-Europe. Concentrations of the most important acidifying species sulfate and nitrate as well as of chloride were measured in 1151 samples with 5 cm resolution from the top 60 m of a 109 m long firn/ice core. This corresponds to a mean time resolution of 8 (bottom) to 14 (top) data points per year. A ²¹⁰Pb nuclear dating showed that the ice core covers a time period between 1850–1981 and that the mean accumulation rate was 0.33 m water equivalent per year. Between the two time periods 1850 – 1880 and 1965 – 1981 the mean sulfate concentrations increased by a factor of 5.8±0.9 and for nitrate by a factor of 2.3±0.3. The mean concentrations at the beginning of the industrial time (period 1850 –1880) was 0.078±0.008 mg/l for sulfate and 0.067±0.005 mg/l for nitrate. The mean chloride concentration was 0.047±0.004 mg/l and did not show a trend in concentration over the time period investigated. A distribution analysis of the measured concentrations for the two time periods 1850 – 1865 and 1965 – 1981 was performed which showed that the data have a nearly log-normal distribution.     

Micro-scale CO2 and CH4 dynamics in a peat soil during a water fluctuation and sulfate pulse

We investigated the response of CO₂ and CH₄ production to a water table fluctuation and a SO₄²⁻ pulse in a bog mesocosm. Net gas production rates in the mesocosm were calculated from concentration data by diffusive mass-balances. Incubation experiments were used to quantify the effect of SO₄²⁻ addition and the distribution of potential CO₂ and CH₄ production rates. Flooding of unsaturated peat resulted in rapid depletion of O₂ and complex patterns of net CH₄, CO₂, and H₂S production. Methane production began locally and without a time lag at rates of 3-4 nmol cm⁻³ d⁻¹ deeper in the peat. Similar rates were determined after a time lag of 10-60 days in the surface layers, whereas rates at lower depths declined. Net CO₂ production was largest immediately after the water table position was altered (100-300 nmol cm⁻³ d⁻¹) and declined to −50-50 nmol cm⁻³ d⁻¹ after a few weeks. SO₄²⁻ addition (500 mM) significantly increased potential CH₄ production rates in the surface layer from an average of 132-201 nmol cm⁻³ d⁻¹ and reduced it below from an average of 418-256 nmol cm⁻³ d⁻¹. Our results suggest that deeper in the peat (40-70 cm) under in situ conditions, methanogenic populations are less impaired by unsaturated conditions than in the surface layers, and that at these depths after flooding the substrate availability for CH₄ and DIC production is significantly enhanced. They also suggest that methanogenic and SO₄²⁻-reducing activity were non-competitive in the surface layer, which might explain contradictory findings from field studies.     

肥料和硫处理对镉胁迫下茭白植物络合素（PCs）含量的影响

以单季茭品种蒋墅茭和双季茭品种葑红早为试材,土壤为栽培介质,对100 mg?L-1 Cd2+胁迫进行不同肥料和不同浓度的硫处理,研究了茭白根系和叶片中的非蛋白巯基、谷胱甘肽及植物络合素含量变化。结果表明：供硫能促进茭白根系和叶片中非蛋白巯基、谷胱甘肽及植物络合素含量的增加,能增强茭白对镉胁迫的抗性;无机肥（三元复合肥）处理的谷胱甘肽、植物络合素含量高于有机肥（菜籽饼）处理;根系中的非蛋白巯基、谷胱甘肽及植物络合素含量显著高于叶片;品种间则以蒋墅茭高于葑红早。     

镉胁迫下硫元素与肥料交互作用对镉在茭白各器官中积累的影响

以茭白（Zizania latifolia Turcz.）的单季茭品种蒋墅茭和双季茭品种葑红早为材料,以土壤为栽培介质,研究了100 mg/L Cd2＋胁迫下,不同浓度硫处理和不同种类肥料交互作用对茭白各器官中Cd2＋积累的影响。研究结果表明,Cd2＋在茭白不同器官的积累表现为根〉短缩茎〉叶〉肉质茎;不同肥料间,有机肥处理下茭白各器官中Cd2＋的积累量同比均显著低于无机肥处理;品种间存在明显差异,葑红早各器官中Cd2＋的积累量高于蒋墅茭;硫元素能促进茭白根系中的Cd2＋向地上部转移。     

Effects of sulfate amendments on mineralization and phosphorus release from South Florida (USA) wetland soils under anaerobic conditions

We investigated the potential effects of elevated water-column sulfate (SO₄) levels on heterotrophic microbial respiration and net phosphorus (P) release for soils collected from impacted and unimpacted Everglades wetlands in south Florida. Soils from three sites, ranging from low P and low SO₄ to high P and high SO₄ environments, were examined under controlled laboratory conditions. The soils were subjected to anaerobic incubations to evaluate net P release and organic matter decomposition in response to SO₄ amendments of 32 or 96 mg l⁻¹ (0.33 and 1.0 mM).Three processes have been described in the literature to explain why SO₄ enrichment may lead to P release from soils under anaerobic conditions. First, alkalinization can lead to a more favorable pH environment for decomposition. For the soils examined here, alkalinization due to the hydrogen ion-consuming reaction of SO₄ reduction was not a prominent mechanism. We found that pH decreased in the incubation vessels, and that increases in alkalinity were more likely attributable to calcium carbonate dissolution than SO₄ reduction. Moreover, all the soils exhibited near circum-neutral pH levels, with moderate to high concentrations of native alkalinity.Second, formation of iron sulfide (FeS_x) compounds has been shown to mobilize iron (Fe)-associated P. Soils from only one of the study sites had Fe concentrations that would be expected to be high enough to influence P mobility. Relatively high porewater Fe:soluble reactive P (SRP) ratios (>83:1) were observed at this site, which suggests that Fe could theoretically exert control over the release of P from the soil. However, soil P levels at this site were too low to measure any substantial influence of Fe on net P mobilization.Finally, availability of electron acceptors such as SO₄ is a major determinant of decomposition rate, and thus rate of organic P release. Amending the soils with SO₄ did not result in either more heterotrophic microbial respiration as measured by carbon dioxide (CO₂) and methane (CH₄) production, or increased net P mobilization. In two of the SO₄-amended soils where post-incubation total sulfide concentrations were as high as 23.4 mg l⁻¹, SO₄ addition reduced production of respiratory carbon end products, suggesting hydrogen sulfide inhibition. Moreover, limitations imposed by substrate quality and low P contributed to the lack of meaningful enhanced decomposition of organic matter with the addition of 32 or 96 mg SO₄ l⁻¹ to the oligotrophic wetland soils. Even though P release did occur under anaerobic conditions for the more enriched site, addition of SO₄ did not enhance P release.     

分光光度法测定水中硫酸盐的前处理方法研究

该文对目前测定水中硫酸盐的铬酸钡分光光度法(HJ/T 342-2007)进行了改进,对改进后的方法进行了检出限、精密度和准确度的检验。结果表明:改进后方法的检出限大大降低,为0.3mg/L,测定下限为1.2mg/L;对不同浓度样品多次重复测定得到实验精密度小于5%;用低浓度标准样品进行准确度检验,测定结果合格。     

Molecular and morpho-physiological characterization of sea,ruderal and cultivated beets

Beta vulgaris genetic resources are essential for broadening genetic base of sugar beet and developing cultivars adapted to adverse environmental conditions. Wild beets (sea beets, B. vulgaris spp. maritima and their naturalized introgressions with cultivated beets known as ruderal beets) harbor substantial genetic diversity that could be useful for beet improvement. Here, we compared molecular and morpho-physiological traits of wild beets collected on the Adriatic coast of Italy with sugar beet using eight primer-pairs amplifying 194 polymorphic fragments and four root traits (glucose and fructose content in the root tip, root elongation rate, number of the of root tips, total root length and its distribution among diameters ranges). Genetic diversity was higher in the sea beet accession, which may be due to the highly variable selection pressures that occur in heterogeneous ecological niches, compared with the ruderal and cultivated beets. Sea and sugar beet accessions showed contrasting root patterns in response to sulfate deprivation: sugar beet showed an increase of reducing sugars in the root tips and higher root elongation rate, and the sea beet accession showed an increase in root tip number, total root length and fine root length (average diameter < 0.5 mm). The ruderal beet showed intermediary responses to sea and sugar beet accessions. AFLP and morpho-physiological cluster analyzes showed sea, ruderal and cultivated beets to be genetically distinct groups. The results of this study indicate variability in response to sulfate deprivation is present in undomesticated beets that could be deployed for sugar beet improvement.