共查询到19条相似文献，搜索用时 187 毫秒
1.
为了解畜牧业发展对若尔盖湿地水生生物类群的影响,本试验设置了A(对照组),B(影响组I),C(影响组II)3个样点,应用稳定同位素技术并结合多维尺度(MDS)等方法研究了若尔盖湿地影响组与对照组之间不同水生生物类群δ~(13)C、δ~(15)N值。结果表明,初级生产者POM(颗粒有机物)样品(主要成分为藻类)δ~(13)C、δ~(15)N值分别为-26.39‰~-21.17‰,3.68‰~6.61‰;浮游动物(枝角类)δ~(13)C、δ~(15)N值分别为-25.69‰~-23.43‰、3.19‰~9.53‰;软体动物泉膀胱螺δ~(13)C、δ~(15)N值分别-28.00‰~-22.30‰、5.19‰~9.27‰,钩虾为-28.57‰~-26.87‰、7.36‰~8.06‰;鱼类样品中高原鳅δ~(13)C、δ~(15)N值分别-30.83‰~-27.01‰、6.41‰~10.02‰,黄河裸裂尻为-26.89‰~-25.95‰、10.24‰~10.89‰。其中不同组间POM样品和浮游动物δ~(13)C值变化不明显,而其δ~(15)N值变化极显著。因此,若尔盖湿地食物网中,氮稳定性同位素信号能较灵敏地反映放牧干扰信息,与软体动物、鱼类相比,POM、浮游动物更适合作为该区域环境评价的指示物种。放牧干扰已经对若尔盖湿地POM、浮游动物等产生了一定的影响,因此,控制若尔盖湿地放牧规模和减少动物粪便的流入量,对于保护若尔盖湿地生态系统的稳定性具有重要意义。 相似文献
2.
黄土高原泾河小流域泥沙碳、氮同位素与生态环境示踪 总被引：1，自引：0，他引：1
以泾河(陕西彬县境内)4条支流表层沉积物为研究对象,对其有机质的稳定碳、氮同位素组成进行测定和研究.结果表明,4条河流表层沉积物有机质的碳同位素(δ13C)值变化范围为(-29.1‰)～(-20.4‰),平均值为-25.4‰.其δ13C值从上游到下游都有逐渐偏正的趋势,表明从上游到下游植被覆盖类型的变化影响了沿河表层沉积物有机质的δ13C值.4条河流表层沉积物有机质的氮同位素(δ15N)值和碳氮比(C/N)的变化范围分别为0～4.6‰和1.4～17.2,平均值分别为2.8‰和7.3.从上游到下游其δ15N值逐渐偏正,表明沿岸进入河中的泥沙比例越来越大,人类活动等对自然环境的影响增强.徐家河和拜家河下游采样点表层沉积物有机质的δ15N值有偏负趋势,可能与下游煤炭开采,煤等有机质进入河流表层沉积物有关.因此,对河流表层沉积物中有机质的碳、氮同位素组成特征和变化研究可以揭示流域土壤侵蚀状态和生态环境的变化. 相似文献
3.
稳定同位素技术通常用于指示外源输入对环境的影响,采用该技术分析了太湖北部不同湖区悬浮颗粒有机物和浮游动物的碳氮稳定同位素比值的差异。结果表明,不同粒径的悬浮颗粒有机物和浮游动物稳定同位素比值存在显著的季节变化,夏季普遍高于冬季,其中δ13C高3.19‰~7.21‰,δ15N高4.20‰~9.36‰。各有机物δ13C不能有效区分各湖区的环境差异,而δ15N在各湖区存在显著差异。δ15N聚类分析显示,河口区由于受外源输入的影响,其δ15N显著低于其他湖区,单独聚为一类,而交汇处和湖心区影响较小,同河口区存在显著差异。整体来讲,总颗粒有机物和浮游动物δ15N同水体TP浓度呈显著正相关,同总溶解性无机氮浓度、铵根离子浓度呈显著负相关。可见,太湖北部悬浮颗粒有机物和浮游动物δ15N受环境营养盐差异的影响强烈,悬浮颗粒有机物δ15N可以作为指示湖区区域差异的有效指标。 相似文献
4.
黄河源区湿地、草地土壤理化性质和碳氮组成及其稳定同位素特征分析 总被引：1，自引：0，他引：1
《水土保持学报》2015,(4)
为探究黄河源区湿地和相邻草地土壤的有机碳和全氮状况,采用野外调查与室内分析相结合,对其理化性质和碳氮组成及其稳定同位素特征进行测定和分析。结果表明,湿地土壤含水量为21.08%~48.95%,容重为0.57~1.46g/cm3,pH为6.4~9.0,全磷含量为34.6~123.44mg/kg,有效磷含量为7.8~71.48mg/kg,有机碳含量为0.53%~16.57%,全氮含量为0.05%~1.47%,δ13 C丰富度介于(-26.65‰)~(-22.10‰)之间,δ15 N丰富度介于1.15‰~5.49‰之间,Corg/N在8.20~11.53之间变化。与湿地邻近的草地土壤含水量变化为13.97%~48.47%,容重变化为0.68~1.42g/cm3,pH为6.1~8.9之间,全磷含量为57.84~143.62mg/kg,有效磷含量为9.74~60.19mg/kg,有机碳含量为0.88%~9.79%,全氮含量为0.09%~0.88%,δ13 C丰富度介于(-25.80‰)~(-21.42‰),δ15 N丰富度介于2.64‰~6.81‰之间,Corg/N在8.60~12.00之间变化。无论是湿地还是草地土壤含水量均50%,但草地土壤的含水量变异范围大于湿地;源区土壤绝大多数呈弱碱性,少部分近中性或呈弱酸性;有机碳和全氮随湿地类型和采样点的不同也存在很大的差异。总体上,湿地土壤的容重、全磷、有效磷、δ13 C、δ15 N、Corg/N低于草地土壤。土壤有机碳氮及其稳定同位素相互间有显著的相关性,土壤有机质的δ13 C表明源区没有C4植物。 相似文献
5.
利用元素分析仪-稳定同位素比率质谱仪检测我国由北到南6个省的10种大米的δ13C和δ15N值。结果显示,我国大米的δ13C值为-28.3‰^-26.0‰,平均值为-27.0±0.8‰,以-27.9‰^-26.3‰出现的频率较高。δ15N值为1.1‰~4.1‰,均值为2.4±1.0‰,以1.7‰~3.4‰出现的频率较高。我国南方大米的δ13C值低于北方大米,但南北方大米的δ15N均值基本相同且小于4‰,符合施化肥大米的特征。根据国内外大米的δ13C和δ15N特异性,以δ13C和δ15N为统计变量,采用Q型系统聚类方法对大米归类溯源。欧式距离<4时,日本大米的3个群集与我国大米的1个群集区分明显;欧式距离<3时,美国大米的2个群集与我国大米的1个群集区分显著。基于大米的δ13C和δ15N特性能够对其产地进行溯源。 相似文献
6.
艾比湖湿地主要盐生植物叶片稳定碳同位素组成研究 总被引：1，自引：0，他引：1
该文分析了艾比湖湿地13科、25属的28种主要盐生植物的稳定碳同位素组成.24种C3植物的δ13C分布范围为-25.67‰～-29.59‰,平均值为-27.85‰,比全球范围调查的植物平均δ13C值(-28.74‰)明显偏正.4种C4植物的δ13C为-16.63‰～-17.39‰,平均值-16.88‰,均属于藜科植物,分布的科较集中.总体上藜科植物适应干旱的能力较其它科植物适应干旱的能力强.灌木/半灌木植物的δ13C值为-27.69‰.灌木/半灌木植物的水分利用效率最高,明显高于一年生草本植物,多年生草本次之.说明盐生灌木/半灌木比一年生草本更适宜于干旱、盐生生境.此外,乔木的δ13C值(-28.16‰)并不是最高,可能是采集物种较少或物种间遗传上的差异造成的.6月和8月的δ13C值比较,总体来看13种植物6月δ13C值明显高于8月,表明6月到8月的生存环境状况或水分条件呈变好趋势. 相似文献
7.
稳定同位素技术是研究土壤元素循环的重要技术手段。本实验研究了同位素标记后的停留时间对水稻地上和地下部分及利用其制备的生物质炭的13C丰度（δ13C）和15N丰度（δ15N）的影响，为深入研究生物质炭对土壤碳、氮过程的影响提供基础。研究以水稻为材料，利用15N-尿素叶面喷施和13C-CO2脉冲标记的方法对水稻进行了15N和13C双标记，15N标记结束后设置4 h、6 h和24 h三个停留时间，将标记后的水稻分为地上和地下部分，分别在300 °C和500 °C下制备成生物质炭，利用同位素质谱仪测定水稻及其生物质炭的δ13C和δ15N。结果表明，随着停留时间的延长，水稻地上部分的δ13C由872‰逐渐降低至578‰，而地下部分的δ13C由226‰逐渐升高至869‰。与δ13C不同，水稻地上部分δ15N呈现先增加后降低的趋势，停留时间6 h时δ15N最大（1764‰），而地下部分的δ15N呈现先降低后增加的趋势。整体而言，与水稻原料相比，生物质炭的δ13C和δ15N分别降低了52.1%和15.9%。而且，生物质炭的δ13C和δ15N均在停留时间为24 h时最高，300 °C生物质炭表现的更加明显。随着停留时间的延长，300 °C生物质炭的热水可提取有机碳的δ13C比残留固体的δ13C降低的比例由4.14%提高到11.0%，而对于500 °C生物质炭则由32.3%降低到18.9%，表明延长停留时间分别降低和提高了300 °C和500 °C生物质炭的13C均匀性。综上所述，本研究发现标记后的停留时间对水稻δ13C和δ15N的影响不同，并且这种影响没有延续至生物质炭，停留时间和制备温度共同影响水稻生物质炭的13C均匀性。 相似文献
8.
荒漠草原土壤有机质碳稳定同位素特征研究 总被引：5，自引：0，他引：5
应用碳稳定同位素分析方法对内蒙古短花针茅荒漠草原土壤有机质及其δ13 C值垂直分布特征、表土δ13C值与建群种-短花针茅δ13 C值的相互关系进行分析,并测定土壤部分理化性质。结果显示:表土有机质含量变化范围为4.17～20.45g/kg;随深度增加,土壤有机碳(SOC)含量呈指数降低,其变化范围为17.98～1.39g/kg,而δ13C值则随剖面深度增加而明显富集,到75cm深度时δ13C值又迅速降低,变化范围为-26.38‰～-13.72‰,变幅>3‰,说明该地区气候和植被状况可能发生过剧烈变化;表土和植物δ13C值分馏程度较其它地区偏大,二者呈极显著相关(r=0.555,P<0.01),进一步说明地上植被状况是影响土壤有机质δ13 C值垂直分布特征的决定性因素。 相似文献
9.
利用预浓缩装置-气相色谱,燃烧-同位素比值质谱仪(PreCon-GC/C-IRMS)联用系统,建立了就采样、浓缩和在线质谱分析大气CH_4中稳定碳同位素组成的测定方法.通过多组试验对比,分析并讨论了利用PreCon-GC/C-IRMS联用技术测定大气CH_4中碳稳定同位素比值的试验条件、系统线性、稳定性及准确度和精密度等.结果表明,在本研究方法条件下,当离子流强度在1.0～20 V时,系统线性良好(斜率S=0.04%./V),在4.0～15 V内其线性(斜率S=0.03%./V)优于总体线性;系统测量稳定性可靠,δ~(13)C值的测定结果的S.D<0.3‰,最大偏差<0.5‰,回收率达99.99%,准确度和精度均符合分析与研究要求.利用该系统对室内和室外草坪地空气中CH_4的碳稳定同位素组成做初步测试,其碳同位素的平均值分别为-31.358‰和-33.085%.,且相同地点区域空气中CH_4的δ~(13)C值,在1d内和不同日期间的变化均在0.5‰以内,重现性良好. 相似文献
10.
不同地域牛尾毛中稳定同位素指纹差异分析 总被引：1，自引：0，他引：1
利用同位素比率质谱仪测定来自黑龙江省安达市青肯泡乡和火石山乡、内蒙古太仆寺旗、河北省张家口市和三河市、山东省德州市和聊城市7个地域牛尾毛中的δ13C、δ15N和δ2H值,比较分析了不同地域来源牛尾毛中稳定同位素指纹特征差异,探讨不同地域来源牛尾毛中稳定同位素组成差异、影响因素及地域差异的范围,为牛肉及其产品同位素指纹溯源技术在实际中的应用提供指导。各区域牛尾毛中δ13C值表现为:黑龙江省安达市青肯泡乡(-14.83‰±2.12)、河北省三河市(-14.20‰±1.19)、山东省德州市(-14.16‰±2.51)和山东省聊城市(-15.78‰±1.08)>黑龙江省安达市火石山乡(-18.87‰±1.69)、内蒙古太仆寺旗(-19.29‰±2.43)和河北省张家口市(-19.83‰±1.92);δ15 N值为:黑龙江省安达市火石山乡(8.07‰±0.95)>内蒙古太仆寺旗(5.73‰±0.85)、河北省张家口市(6.65‰±1.45)>黑龙江省安达市青肯泡乡(4.60‰±0.41)、河北省三河市(4.24‰±0.75)、山东省德州市(4.18‰±0.96)和山东省聊城市(4.90‰±0.46);δ2H值为:河北省三河市(-87.78‰±1.99)、山东省德州市(-87.91‰±3.19)和山东省聊城市(-89.24‰±2.90)>河北省张家口市(-94.07‰±3.38)>黑龙江省安达市火石山乡(-97.05‰±3.41)、内蒙古太仆寺旗(-97.55‰±2.79)>黑龙江省安达市青肯泡乡(-102.25‰±2.99)。不同地域来源牛尾毛中稳定碳、氮、氢同位素指纹差异及地域差异范围取决于不同地域喂养牛的饲料组成、地域海拔和纬度的差异程度。 相似文献
11.
Kropf U Golob T Nečemer M Kump P Korošec M Bertoncelj J Ogrinc N 《Journal of agricultural and food chemistry》2010,58(24):12794-12803
Isotope parameters (δ(13)C(honey), δ(13)C(protein), δ(15)N) were determined for 271 honey samples of 7 types (black locust, multifloral, lime, chestnut, forest, spruce, and fir honeys) from 4 natural geographical regions of Slovenia. Carbon and nitrogen stable isotope ratios were measured to elucidate the applicability of this method in the identification of the botanical and geographical origin of honey and in honey adulteration. Only 2.2% of the samples were adulterated according to the internal standard carbon isotope ratio analysis method. Botanical origin did not have any major influence on the honey isotope profiles; only black locust honey showed higher δ(13)C values. Some differences were seen across different production years, indicating that the influence of season should be further tested. Statistical and multivariate analyses demonstrated differences among honeys of various geographical origins. Those from the Alpine region had low δ(13)C (-26.0‰) and δ(15)N values (1.1‰); those from the Mediterranean region, high δ(13)C (-24.6‰) and medium δ(15)N values (2.2‰); those from the Pannonian region, medium δ(13)C (-25.6‰) and high δ(15)N value (3.0‰); and those from the Dinaric region, medium δ(13)C (-25.7‰) and low δ(15)N values (1.4‰). 相似文献
12.
不同放牧强度下荒漠草原土壤有机碳及其δ~(13)C值分布特征 总被引：3，自引：0，他引：3
以内蒙古短花针茅荒漠草原为研究对象,通过测定不同载畜率下土壤部分理化性质、土壤有机碳含量和δ~(13)C值.探讨随放牧强度增加土壤有机碳深度分布和δ~(13)C值的组成差异特征.结果显示:随深度增加.有机碳含量呈线性急剧降低,变化范围在16.17～6.26 g/kg之间,而土壤有机碳的δ~(13)C值不断增大.变化范围在-22.5‰～-14.3‰.放牧对土壤有机碳的影响主要在0-20 cm土层,且放牧强度越大,有机碳含量越低,有机质分解程度越大,δ~(13)C值越偏正,δ~(13)C值的深度变化特征还表明.土壤剖面形成发育过程中当地气候和植被发生了很大的变化,可能实现了由C_4植物占优势向C_3植物占优势的变迁. 相似文献
13.
Patricia P. Videla Andrea J. Farwell Barbara J. Butler D. George Dixon 《Water, air, and soil pollution》2009,197(1-4):107-119
Naphthenic acids (NAs) are a complex group of naturally occurring oil sands constituents that constitute a significant portion of the dissolved organic carbon (DOC) pool available for microbial degradation in the process-related waste water associated with oil sands mine sites. One approach to understanding the biological fate of oil sands process-derived carbon and nitrogen in aquatic reclamation of the mine sites involves the use of stable isotope analyses. However, for stable isotope analyses to be useful in such field-based assessments, there is a need to determine how microbial degradation of a complex mixture of NAs might change the stable isotope values (δ 13C, δ 15N). In batch cultures and semi-continuous laboratory microcosms, utilization of a commercial mixture of NAs by oil sands-derived microbial cultures resulted in microbial biomass that was similar or slightly 13C enriched (1.4‰ to 3.0‰) relative to the DOC source, depending on the length of incubation. Utilization of a NA-containing extract of oil sands processed water resulted in greater 13C enrichment of microbial biomass (8.5‰) relative to the DOC source. Overall, the δ 13C of the DOC comprised of complex mixtures of NAs showed minimal change (?0.5‰ to ?0.1‰) during the incubation period whereas the δ 13C of the dissolved inorganic carbon (DIC) was more variable (?5.0‰ to +5.4‰). In tests where the concentration of available nitrogen was increased, the final biomass values were 15N enriched (3.8‰ to 8.4‰) relative to the initial biomass. The isotope trends established in this study should enhance our ability to interpret field-based data from sites with hydrocarbon contamination, particularly in terms of carbon source utilization and 15N enrichment. 相似文献
14.
Damien Finn Fred Oudyn Kerrilyn Catton Ram Dalal 《Communications in Soil Science and Plant Analysis》2016,47(17):2017-2025
Labile soil dissolved organic carbon (DOC) and heat-extracted carbon (HEC) are sensitive indicators of changing soil organic carbon (SOC) stocks. Isotope ratio mass spectrometry (IRMS) is an important tool for studying SOC turnover and soil biological function. Several complications are involved in measuring DOC/HEC, for example salt ionic strength; solution pH; and anionic damage to elemental analyzer-IRMS. We evaluated a method for DOC/HEC analysis with 0.1 M potassium phosphate buffer (PPB). This method was strongly correlated with commonly used carbon (C) extractants for C quantification. Carbon-13 comparisons between DOC/HEC extracted with Milli-Q water and PPB were similar. The δ13C (‰) values of particulate OC and DOC were similar, whereas the relationship between humic OC and HEC was soil specific. An incubation experiment demonstrated that DOC/HEC δ13C (‰) successfully explained respired microbial carbon dioxide over 90 days. We conclude that this method represents an alternative for DOC/HEC quantification and δ13C (‰) analyses. 相似文献
15.
Soil physical structure causes differential accessibility of soil organic carbon (SOC) to decomposer organisms and is an important determinant of SOC storage and turnover. Techniques for physical fractionation of soil organic matter in conjunction with isotopic analyses (δ13C, δ15N) of those soil fractions have been used previously to (a) determine where organic C is stored relative to aggregate structure, (b) identify sources of SOC, (c) quantify turnover rates of SOC in specific soil fractions, and (d) evaluate organic matter quality. We used these two complementary approaches to characterize soil C storage and dynamics in the Rio Grande Plains of southern Texas where C3 trees/shrubs (δ13C=−27‰) have largely replaced C4 grasslands (δ13C=−14‰) over the past 100-200 years. Using a chronosequence approach, soils were collected from remnant grasslands (Time 0) and from woody plant stands ranging in age from 10 to 130 years. We separated soil organic matter into specific size/density fractions and determined their C and N concentrations and natural δ13C and δ15N values. Mean residence times (MRTs) of soil fractions were calculated based on changes in their δ13C with time after woody encroachment. The shortest MRTs (average=30 years) were associated with all particulate organic matter (POM) fractions not protected within aggregates. Fine POM (53-250 μm) within macro- and microaggregates was relatively more protected from decay, with an average MRT of 60 years. All silt+clay fractions had the longest MRTs (average=360 years) regardless of whether they were found inside or outside of aggregate structure. δ15N values of soil physical fractions were positively correlated with MRTs of the same fractions, suggesting that higher δ15N values reflect an increased degree of humification. Increased soil C and N pools in wooded areas were due to both the retention of older C4-derived organic matter by protection within microaggregates and association with silt+clay, and the accumulation of new C3-derived organic matter in macroaggregates and POM fractions. 相似文献
16.
The results of investigation into the composition of stable carbon and nitrogen isotopes of organic matter in the soils developed within soil–sedimentary sequences in the central part of the Selenga Middle Mountains in the Late Glacial and Holocene are presented. In the past 15000 years, the organic matter of the investigated soils has only been formed from the biomass of C3 plants (without the participation of C4 plants). This is confirmed by the of δ13С values from–27.00 to–23.35‰. A combined analysis of the parameters of the organic matter (Сorg, Ntotal, C/N, δ13С, and δ15N) of soils formed in different periods makes it possible to assume that the isotopic composition of carbon and nitrogen reflects changes in the climate humidity during the Late Glacial and Holocene periods. The specified intervals of soil formation correspond to the climate humidification and stabilization of the surface owing to the development of dense vegetation. Aridization periods were characterized by the accumulation of sediments that buried soil horizons. The most pronounced stages of climate aridization occurred at the transition from the Late Glacial to the Holocene, from the Boreal to the Atlantic, and from the Atlantic to the Subboreal periods. The optimum soil-forming conditions existed in the periods of 11700–11000, 8800–6900, and 4700–1000 years ago, which is confirmed by the published data on the landscape-climatic changes in the adjacent areas in the past 15000 years. 相似文献
17.
In order to evaluate the sustainability and efficiency of soil carbon sequestration measures and the impact of different management and environmental factors, information on soil organic matter (SOM) stability and mean residence time (MRT) is required. However, this information on SOM stability and MRT is expensive to determine via radiocarbon dating, precluding a wide spread use of stability measurements in soil science. In this paper, we test an alternative method, first developed by Conen et al. (2008) for undisturbed Alpine grassland systems, using C and N stable isotope ratios in more frequently disturbed agricultural soils. Since only information on carbon and nitrogen concentrations and their stable isotope ratios is required, it is possible to estimate the SOM stability at greatly reduced costs compared to radiocarbon dating. Using four different experimental sites located in various climates and soil types, this research proved the effectiveness of using the C/N ratio and δ15N signature to determine the stability of mOM (mineral associated organic matter) relative to POM (particulate organic matter) in an intensively managed agro-ecological setting. Combining this approach with δ13C measurements allowed discriminating between different management (grassland vs cropland) and land use (till vs no till) systems. With increasing depth the stability of mOM relative to POM increases, but less so under tillage compared to no-till practises. Applying this approach to investigate SOM stability in different soil aggregate fractions, it corroborates the aggregate hierarchy theory as proposed by Six et al. (2004) and Segoli et al. (2013). The organic matter in the occluded micro-aggregate and silt & clay fractions is less degraded than the SOM in the free micro-aggregate and silt & clay fractions. The stable isotope approach can be particularly useful for soils with a history of burning and thus containing old charcoal particles, preventing the use of 14C to determine the SOM stability. 相似文献
18.
FuShun Wang Congqiang Liu Minghong Wu Yuanxiu Yu Fengwei Wu Senlin Lü Zhongqing Wei Gang Xu 《Water, air, and soil pollution》2009,199(1-4):159-170
Sediment cores were collected from the central and northern parts of Lake Dianchi, a large and shallow eutrophic lake situated in southwest China. Total organic carbon, total nitrogen (TN), and total phosphorus (TP) as well as the δ13C and δ15N were analyzed in the sediment cores. Age model of the sediment cores were established according to 137Cs geochronology, which reveals that the sedimentary record covers a period of the last 50 years. During that time, Dianchi had been undergoing a distinct conversion from oligotrophic to eutrophic, as a result of increasing nutrient loadings. The two cores displayed similar increases for values of TN and δ15N, and the variations of the both parameters matched well with that of TP, which presumably suggested that δ15N is a reliable proxy for anthropogenic nutrient input. Also, dynamics of δ15N and TP showed that anthropogenic nutrients input seemed to start in the 1970s. The upward elevation of δ15N might be ascribed to the increasing input of isotopically heavier dissolved inorganic nitrogen and the accelerated denitrification process when the lake water was oxygen-depleted. The less variation of δ15N in the uppermost several centimeters of both cores were probably the result of pollution controls carried out by the local government in the recent decade. The upward increasing of δ13C in the two cores seemed to be induced by the enhanced productivity since 1980, which was in accordance with limnological observation. Therefore, δ13C values were believed to be an effective proxy for reconstructing the history of eutrophication in Lake Dianchi. In addition, this study also suggested that carbon and nitrogen isotopes are applicable to large, shallow lakes in interpreting the past environmental change. 相似文献
19.
本研究针对北京郊区汇源与正谷有机蔬菜基地,通过对不同蔬菜生产基地取样分析,研究有机和常规蔬菜生产条件下土壤养分平衡特征,分析有机生产蔬菜和土壤的15N特征。结果表明,（1）有机蔬菜生产与常规生产对比,由于施肥数量不同,汇源有机蔬菜基地土壤N、P及K盈余量（分别为356～472kg·hm-2、298kg·hm-2和200～226kg·hm-2）高于当地常规生产,而正谷有机蔬菜生产土壤N、P及K养分盈余量（分别为-164～190kg·hm-2、107.9～435.5kg·hm-2和-164.5～-136.8kg·hm-2）低于当地常规生产;（2）汇源有机蔬菜生产模式中,土壤N素养分有逐季累积的趋势,有机肥的N、P和K养分存在着不平衡性,这可能是造成0～20cm土层磷素大量累积的重要原因;（3）蔬菜类别不同,δ15N值不同,一般为叶菜类最高（10.49‰）,果菜类次之（10.07‰）,根菜类δ15N值最低（5.62‰）;（4）植物不同部位δ15N值也有差异。针对圆椒的分析表明,圆椒叶δ15N（12.44‰）〉圆椒果实δ15N（9.35‰）;（5）土壤δ15N与土壤全N之间有一定的相关性,回归方程为δ15N土壤=13.098N土壤＋3.7624,R2=0.938,而植物δ15N与土壤δ15N之间、植物δ15N与土壤全氮相关性较差。长期施用有机肥,使得土壤中15N更多来自有机肥,进而表现为蔬菜δ15N升高,高量有机肥可以短期内增加叶菜类植物δ15N值。 相似文献