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1.
铵态氮和硝态氮对香蕉枯萎病发生的比较研究 总被引：5，自引：0，他引：5
为寻找降低香蕉枯萎病发生的防治措施,通过室内盆栽接种试验,研究了铵态氮(NH4+-N)和硝态氮(NO3--N)对香蕉枯萎病发生及其植株叶绿素含量、气体交换参数、病原菌在植物体内的数量分布和植物钙(Ca)、镁(Mg)、铁(Fe)、钼(Mo)、可溶性糖和木质素含量的效应。结果表明:不接种病原菌的条件下,不同氮素处理对香蕉幼苗生长影响无差异;接菌情况下,与NH4+-N处理相比,NO3--N处理显著降低植株各器官的病原菌数量、发病率和发病严重程度。病原菌侵染后,不同氮素处理下植株光合作用均显著下降:NO3--N处理香蕉苗保持比NH4+-N处理更高的光合速率;病原菌侵染后NH4+-N处理的植株Ca、Mg、Fe和Mo含量相对于侵染前没有显著差异,但NO3--N处理下此4种元素含量均显著升高。病原菌侵染后的植株叶片可溶性糖含量在不同氮素处理中都没有显著变化,但在根系中,NO3--N处理的侵染植株可溶性糖含量显著降低。与此同时,病原菌侵染后,木质素含量在NH4+-N处理植株中变化不显著,但其含量在NO3--N处理侵染后显著上升。综上所述,NO3--N处理可增加植株抗病相关矿质元素的吸收,诱导香蕉苗木质素形成,使其木质化程度增加,从而维持较高的光合作用,保持较高的抗病水平。 相似文献
2.
新疆克里雅河流域绿洲区地下水作为农业生产和生活饮用主要水源之一,研究地下水中"三氮"分布特征和影响因素对该地区地下水保护具有重要意义。通过数理统计方法、空间插值法等对研究区41组地下水水样检测结果进行分析。结果表明:克里雅河流域平原区地下水中NH4+-N、NO2--N和NO3--N含量随着时间呈增加趋势,其中NO2--N达到地下水质量标准Ⅲ类水标准,2017年和2021年NH4+-N都存在超标点,超标率分别为6.7%和41.7%,2021年NO3--N存在超标点,超标率为25.0%;空间上,地下水中"三氮"含量较高地区分布在克里雅河流域中游沿岸的绿洲带上,呈零星分布,该区域受到人类活动影响较大;研究区内地下水"三氮"含量受到自然因素和人为因素共同影响,人为因素占主导地位,氮肥的施用、人畜粪便、生活污水是地下水中氮的主要来源。 相似文献
3.
以科尔沁沙地不同林龄(15 a、25 a、35 a和45 a)樟子松林为对象,研究其0~100 cm土层土壤有机碳、全氮和全磷含量及其生态化学计量特征,探讨土壤碳氮磷化学计量特征的垂直分布规律及随林龄的变化规律。结果表明:(1)4种林龄樟子松林土壤(0~20 cm土层)有机碳、全氮和全磷含量分别为7.34、0.39 g·kg~(-1)和0.19 g·kg~(-1),均低于全国平均水平。(2)随着林龄的增加,有机碳含量、C/N和C/P均呈现增大的趋势;全氮和全磷含量呈现先增加后降低(45 a生林分显著降低);而N/P的变化不显著。(3)随着土层的加深,有机碳和全氮含量的变化趋势基本一致,均呈现逐渐降低的趋势,但是各林分在0~20 cm土层中的有机碳和全氮含量均不足总含量的1/3;C/N和C/P呈现相反的变化趋势(C/N增加、C/P降低);而全磷含量和N/P的垂直分布较为均匀,变化不大。综上所述,本研究区樟子松林土壤中的有机碳、全氮、全磷含量极为贫瘠,但樟子松人工林种植增加了土壤碳、氮、磷养分含量;各林龄樟子松林土壤同时受氮、磷养分的限制,但随土层加深受氮的限制更为显著。 相似文献
4.
《干旱区资源与环境》2019,(11):190-194
为探讨内蒙古苏木山华北落叶松人工林土壤养分状况,选择该林区4个林龄(17a、26a、37a、48a)华北落叶松人工林,对不同林龄、不同土层间的土壤化学性质进行综合比较,利用主成分分析和回归分析的方法,计算土壤养分综合指标值,构建林龄与土壤养分综合指标值的回归方程,分析土壤养分的变化规律。结果显示:随着林龄增加,土壤pH值逐渐降低,土壤存在酸化趋势;土壤全效养分以幼龄林时最高,中龄林、近熟林时达到最低;土壤速效养分中碱解氮在中龄林含量最高,而后随林龄增加而降低至成熟林时降至最低,速效磷、速效钾含量均随林龄增加而降低;空间分布上,土壤pH值随土层加深而升高,其他各养分指标均随土层加深而降低,在土壤上层较显著;所构建的回归方程决定系数为0.880,能够较好的反应出林龄与土壤养分综合指标间的关系;幼龄林(17a)、中龄林(26a)、近熟林(37a)、成熟林(48a)土壤养分指标综合得分分别为:0.945、0.069、-0.50、-0.509,幼龄林土壤养分最好,成熟林土壤养分最差。 相似文献
5.
以科尔沁沙地不同林龄（15 a、25 a、35 a和45 a）樟子松林为对象,研究其0-100 cm土层土壤有机碳、全氮和全磷含量及其生态化学计量特征,探讨土壤碳氮磷化学计量特征的垂直分布规律及随林龄的变化规律。结果表明：（1）4种林龄樟子松林土壤（0-20 cm土层）有机碳、全氮和全磷含量分别为7.34、0.39 g·kg^-1和0.19 g·kg^-1,均低于全国平均水平。（2）随着林龄的增加,有机碳含量、C/N和C/P均呈现增大的趋势;全氮和全磷含量呈现先增加后降低（45 a生林分显著降低）;而N/P的变化不显著。（3）随着土层的加深,有机碳和全氮含量的变化趋势基本一致,均呈现逐渐降低的趋势,但是各林分在0-20 cm土层中的有机碳和全氮含量均不足总含量的1/3;C/N和C/P呈现相反的变化趋势（C/N增加、C/P降低）;而全磷含量和N/P的垂直分布较为均匀,变化不大。综上所述,本研究区樟子松林土壤中的有机碳、全氮、全磷含量极为贫瘠,但樟子松人工林种植增加了土壤碳、氮、磷养分含量;各林龄樟子松林土壤同时受氮、磷养分的限制,但随土层加深受氮的限制更为显著。 相似文献
6.
为探究不同灌溉水矿化度对棉田土壤呼吸速率的影响,设置了4个灌溉水矿化度,分别为0.85 g·L-1(CK,当地灌溉水矿化度)、3 g·L-1(S1)、5 g·L-1(S2)和8 g·L-1(S3),在新疆进行了膜下滴灌棉花大田试验。在棉花生育期,每月采集两次土壤呼吸速率值(Rs),并同时监测土壤温度(ST)、含水率(SWC)、电导率(EC)、硝态氮含量(NO3--N)、铵态氮含量(NH4+-N),运用通径分析研究了灌溉水矿化度下土壤参数对土壤呼吸速率的影响。结果表明：微咸水灌溉(S1和S2)在一定程度上提高了土壤含水率、电导率和铵态氮含量;咸水灌溉(S3)显著增加了土壤水分和盐分,并降低了土壤硝态氮含量;灌溉水矿化度的增加会减弱土壤呼吸速率。土壤的水分和温度与呼吸速率的相关性,随灌溉水矿化度的增加而呈减弱趋势。通过运用二次函数式来表示0～10 cm的土层温度对土壤呼吸速率的响应(R... 相似文献
7.
乌鲁木齐大气总悬浮颗粒物（TSP）离子化学组分及影响因素 总被引：1，自引：0，他引：1
利用2009年乌鲁木齐4个大气总悬浮颗粒物（TSP）观测站点资料,采用离子色谱仪分析了TSP中水溶性离子成分。结果表明：① 2009年乌鲁木齐市区3站总离子浓度为151.28 μg/m3,白杨沟为40.83 μg/m3。4站NO3-/SO42-比值较小,表明乌鲁木齐大气污染主要来自于固定污染源。② 2009年乌鲁木齐4站TSP中SO42-、Ca2+、NO3-和NH4+的浓度高于其他各离子,各站离子浓度有明显的季节变化特征,采暖期各离子浓度明显增加,SO42-、NO3-增幅最大。③ 对各主要离子进行相关性分析,得到NH4+与SO42-的相关系数为0.828,与NO3-的相关系数为0.659,说明铵盐化合物主要以硫酸铵和硝酸铵的形式存在;SO42-与NO3-的相关性很大,相关系数为0.973,表明二者主要来自二氧化硫和氮氧化物,排放方式与在大气中的传输途径较一致;地壳元素Ca2+和Mg2+有很好的相关性,相关系数是0.914,表明二者来源相似,可能主要来自风沙土壤尘、道路尘和建筑尘。 相似文献
8.
密怀顺地区是北京市重要的水源涵养区,直接影响着主城区的供水安全。2014年南水北调盈余水量通过潮白河河道回补地下水,地下水位不断抬升,使常年积累在耕地土壤中NO3--N对地下水环境风险不断增加。通过对地下水中NO3--N和耕地属性地块研究。结果表明:1)2015-2018年研究区地下水NO3--N浓度有升高趋势;2)2015-2018年研究区水质稳定区面积达到164.26km2,占比33.78%;其次为水质略变差区和水质变差区,面积分别为136.76km2和112.74km2,占比分别为28.12%和23.18%。3)耕地属性不变的7个有监测地块地下水NO3--N浓度均有不同程度升高,MW-3和MW-1地块超过地下水Ⅲ类水质标准;4)地下水NO3--N含量变化与地下水回补有一定关联。 相似文献
9.
为了研究樟子松人工固沙林林分密度对土壤理化特性的影响,在章古台地区选取林分密度分别为625（P1）、775（P2）、1 025（P3）、1 175（P4）株·hm-2和1 250（P5）株·hm-2的樟子松中龄林（林龄为23~27 a）为研究对象,对0~100 cm深度的樟子松林地土壤按0~10、10~20、20~40、40~60、60~80、80~100 cm进行分层,分析其理化特性。结果表明：0~10 cm土层全氮和20~40 cm土层土壤容重随密度增加呈上升趋势,P5显著高于P1（P <
0.05）;0~80 cm土层全钾和0~60 cm土层pH随密度增加先升高后降低,P3最高,且P3样地全钾在10~60 cm土层显著高于P1（P < 0.05）;pH在0~40 cm土层显著高于其他样地（P <
0.05）;0~10 cm土层全磷随密度增加而减小,P1显著高于P3~P5（P < 0.05）;P4或P5样地有效钾在0~40 cm土层显著高于P1、P2样地（P < 0.05）,在40~100
cm土层显著高于P3样地（P < 0.05）;P2~P4样地的土壤孔隙度在40~100 cm土层低于P1和P5样地。综合考虑林分密度对樟子松中龄林土壤理化特性的影响,章古台地区樟子松林的合理林分密度为1 025~1 175株·hm-2,可采取间伐等营林管理措施调节林分密度,确保樟子松固沙林生长具有良好的土壤条件。 相似文献
10.
《干旱区资源与环境》2017,(12):161-165
研究了章古台地区沙地樟子松人工林不同林龄(10a,20a,35a,50a,60a)不同深度(20cm,40cm,60cm,80cm,100cm,120cm,140cm,160cm,180cm)的土壤含水量变化的分层特征。结果表明:沙地樟子松人工林地各土壤层次水分含量随林龄的不同表现各异。依据土壤含水量的不同将沙地樟子松人工林地土壤层次分为3层,即表层、根系层和稳定层,各林龄的层次分别为:10a林龄林地无明显表层,100cm土层以上为根系层,120cm土层以下为稳定层;20a林龄林地40cm以上为表层,60-140cm为根系层,160cm以下为稳定层;35a林龄林地40cm土层以上为表层,60-100cm为根系层,120cm以下为稳定层;50a林龄林地40cm以上为表层,60-120cm为根系层,140cm以下为稳定层;60a林龄林地40cm以上为表层,60-100cm为根系层,120cm以下为稳定层。 相似文献
11.
Yibo ZHANG 《干旱区科学》2017,9(6):810-822
Due to increasing global demand for crop production and energy use, more and more reactive nitrogen(Nr) has been generated and emitted to the environment. As a result, global atmospheric nitrogen(N) deposition has tripled since the industrial revolution and the ecological environment and human health have been harmed. In this study, we measured dry and wet/bulk N deposition from July 2013 to December 2015 in a semi-arid grassland of Duolun County, Inner Mongolia, China. The samples of dry and wet/bulk N deposition were collected monthly with a DELTA(DEnuder for Long Term Atmospheric sampling) system and with Gradko passive samplers and a precipitation gauge. The measured results show that the annual mean concentrations of NH_3, NO_2, HNO_3, particulate NH_4~+(pNH_4~+) and particulate NO_3~-(pNO_3~-) in atmosphere were 2.33, 1.90, 0.18, 1.42 and 0.42 μg N/m3, respectively, and that the annual mean volume-weighted concentrations of NH_4~+-N and NO_3~--N in precipitation were 2.71 and 1.99 mg N/L, respectively. The concentrations of Nr components(including NH_3, NO_2, HNO_3, p NH_4~+, pNO_3~-, NH_4~+-N and NO_3~--N) exhibited different seasonal variations. Specifically, NO_2 and HNO_3 exhibited higher concentrations in autumn than in summer, while the other Nr components(NH_3, pNH_4~+, pNO_3~-, NH_4~+-N and NO_3~--N) showed the highest values in summer. Based on measured concentrations of Nr components and their deposition velocities estimated using the GEOS-Chem global atmospheric chemical transport model, the calculated annual mean dry deposition fluxes were 3.17, 1.13, 0.63, 0.91 and 0.36 kg N/(hm~2·a) for NH_3, NO_2, HNO_3, p NH_4~+ and pNO_3~-, respectively, and the calculated annual mean wet/bulk deposition fluxes were 5.37 and 3.15 kg N/(hm~2·a) for NH_4~+-N and NO_3~--N, respectively. The estimated annual N deposition(including dry N deposition and wet/bulk N deposition) reached 14.7 kg N/(hm~2·a) in grassland of Duolun County, approaching to the upper limit of the N critical load(10–15 kg N/(hm~2·a)). Dry and wet/bulk deposition fluxes of all Nr components(with an exception of HNO_3) showed similar seasonal variations with the maximum deposition flux in summer and the minimum in winter. Reduced Nr components(e.g., gaseous NH_3 and p NH_4~+ in atmosphere and NH_4~+-N in precipitation) dominated the total N deposition at the sampling site(accounted for 64% of the total N deposition), suggesting that the deposited atmospheric Nr mainly originated from agricultural activities. Considering the projected future increases in crop and livestock production in Inner Mongolia, the ecological and human risks to the negative effects of increased N deposition could be increased if no mitigation measures are taken. 相似文献
12.
Nitrogen (N) and phosphorus (P) are two essential nutrients that determine plant growth and many nutrient cycling processes. Increasing N and P deposition is an important driver of ecosystem changes. However, in contrast to numerous studies about the impacts of nutrient addition on forests and temperate grasslands, how plant foliar stoichiometry and nutrient resorption respond to N and P addition in alpine grasslands is poorly understood. Therefore, we conducted an N and P addition experiment (involving control, N addition, P addition, and N+P addition) in an alpine grassland on Kunlun Mountains (Xinjiang Uygur Autonomous Region, China) in 2016 and 2017 to investigate the changes in leaf nutrient concentrations (i.e., leaf N, Leaf P, and leaf N:P ratio) and nutrient resorption efficiency of Seriphidium rhodanthum and Stipa capillata, which are dominant species in this grassland. Results showed that N addition has significant effects on soil inorganic N (NO3--N and NH4+-N) and leaf N of both species in the study periods. Compared with green leaves, leaf nutrient concentrations and nutrient resorption efficiency in senesced leaves of S. rhodanthum was more sensitive to N addition, whereas N addition influenced leaf N and leaf N:P ratio in green and senesced leaves of S. capillata. N addition did not influence N resorption efficiency of the two species. P addition and N+P addition significantly improved leaf P and had a negative effect on P resorption efficiency of the two species in the study period. These influences on plants can be explained by increasing P availability. The present results illustrated that the two species are more sensitive to P addition than N addition, which implies that P is the major limiting factor in the studied alpine grassland ecosystem. In addition, an interactive effect of N+P addition was only discernable with respect to soil availability, but did not affect plants. Therefore, exploring how nutrient characteristics and resorption response to N and P addition in the alpine grassland is important to understand nutrient use strategy of plants in terrestrial ecosystems. 相似文献
13.
沙地樟子松人工林土壤酶活性及其影响因子 总被引：1，自引：0，他引：1
采用通径分析的方法对辽宁省章古台地区10~60 a沙地樟子松人工林的多种土壤理化因子与5种土壤酶活性进行分析。结果表明：5种土壤酶活性与多数土壤理化因子相关性显著，土壤酶活性能够表征该区域土壤综合肥力状况。不同土壤酶活性主要影响因子不同，蔗糖酶主要影响因子综合作用排序为：有机质>黏粒>速效磷>pH；蛋白酶主要影响因子综合作用排序为：碱解氮>速效钾>含水率；磷酸酶主要影响因子综合作用排序为：全磷>速效钾>粉粒；过氧化氢酶主要影响因子综合作用排序为：pH>容重>全磷>全钾；脲酶主要影响因子综合作用排序为：pH>黏粒>全氮>含水率。与简单相关分析相比，通径分析方法能更深入地了解土壤酶活性和土壤理化因子的关系，期望通过对土壤酶活性主要影响因子的研究为樟子松人工林的抚育和土壤改良提供依据。 相似文献
14.
The soil type is a key factor influencing N(nitrogen) cycling in soil; however, gross N transformations and N_2O emission sources are still poorly understood. In this study, a laboratory ~(15)N tracing experiment was carried out at 60% WHC(water holding capacity) and 25℃ to evaluate the gross N transformation rates and N_2O emission pathways in sandy loam and silt loam soils in a semi-arid region of Heilongjiang Province, China. The results showed that the gross rates of N mineralization, immobilization, and nitrification were 3.60, 1.90, and 5.63 mg N/(kg·d) in silt loam soil, respectively, which were 3.62, 4.26, and 3.13 times those in sandy loam soil, respectively. The ratios of the gross nitrification rate to the ammonium immobilization rate(n/ia) in sandy loam soil and silt loam soil were all higher than 1.00, whereas the n/ia in sandy loam soil(4.36) was significantly higher than that in silt loam soil(3.08). This result indicated that the ability of sandy loam soil to release and conserve the available N was relatively poor in comparison with silt loam soil, and the relatively strong nitrification rate compared to the immobilization rate may lead to N loss through NO_3~– leaching. Under aerobic conditions, both nitrification and denitrification made contributions to N_2O emissions. Nitrification was the dominant pathway leading to N_2O production in soils and was responsible for 82.0% of the total emitted N_2O in sandy loam soil, which was significantly higher than that in silt loam soil(71.7%). However, the average contribution of denitrification to total N_2O production in sandy loam soil was 17.9%, which was significantly lower than that in silt loam soil(28.3%). These results are valuable for developing reasonable fertilization management and proposing effective greenhouse gas mitigation strategies in different soil types in semiarid regions. 相似文献
15.
Excessive fertilization combined with unreasonable irrigation in farmland of the Hetao Irrigation Area (HIR), China, has resulted in a large amount of nitrogen (N) losses and agricultural non-point source pollution. Application of soil amendments has become one of the important strategies for reducing N losses of farmland. However, there is still no systematic study on the effects of various soil amendments on N losses in the HIR. In this study, three types of soil amendments (biochar, bentonite and polyacrylamide) were applied in a maize-wheat rotation system in the HIR during 2015-2017. Yields of maize and wheat, soil NH3 volatilization, N2O emission and NO3- leaching were determined and soil N balance was estimated. The results showed that applications of biochar, bentonite and polyacrylamide significantly increased yields of maize by 9.2%, 14.3% and 13.3%, respectively, and wheat by 9.2%, 16.6% and 12.3%, respectively, compared with the control (fertilization alone). Applications of biochar, bentonite and polyacrylamide significantly reduced soil N leaching by 23.1%, 35.5% and 27.1%, soil NH3-N volatilization by 34.8%, 52.7% and 37.8%, and soil N surplus by 23.9%, 37.4% and 30.6%, respectively. Applications of bentonite and polyacrylamide significantly reduced N2O-N emissions from soil by 37.3% and 35.8%, respectively, compared with the control. Compared with application of biochar, applications of bentonite and polyacrylamide increased yields of maize and wheat by 5.1% and 3.5%, respectively. Our results suggest that soil amendments (bentonite and polyacrylamide) can play important roles in reducing N losses and increasing yield for the maize-wheat rotation system in the HIR, China. 相似文献
16.
Zongjie LI 《干旱区科学》2017,9(6):911-923
Precipitation chemistry analysis is essential to evaluate the atmospheric environmental quality and identify the sources of atmospheric pollutants. In this study, we collected a total of 480 precipitation samples at 6 sampling sites in the northern and southern slopes of Wushaoling Mountain from May 2013 to July 2014 to analyze the chemical characteristics of precipitation and to identify the main sources of ions in precipitation. Furthermore, we also explored the indicative significance for sand dust events in the northern and southern slopes of Wushaoling Mountain based on the precipitation chemistry analysis.During the sampling period(from May 2013 to July 2014), the p H values, EC(electrical conductivity)values and concentrations of cations(Ca~(2+), Mg~(2+), Na~+, K~+ and NH_4~+) and anions(SO_4~(2–), NO_3~–, Cl~–, NO_2~– and F~–) in precipitation were different in the northern and southern slopes at daily and seasonal time scales, with most of the values being higher in the northern slope than in the southern slope. The chemical type of precipitation in the southern and northern slopes was the same, i.e.,SO_4~(2–)-Ca~(2+)-NO_3~–-Na~+. The concentrations of ions in precipitation were mainly controlled by terrigenous material and anthropogenic activities(with an exception of Cl~–). The concentration of Cl~– in precipitation was mainly controlled by the sea salt fraction. The concentrations of Na+ and Cl~– showed an increasing trend after the occurrence of sand dust events both in the northern and southern slopes. In addition, after the occurrence of sand dust events, the concentrations of K~+, Mg~(2+), SO_4~(2–), NO_3~– and Ca~(2+) showed an increasing trend in the southern slope and a decreasing trend in the northern slope. It is our hope that the results may be helpful to further understand the atmospheric pollution caused by sand dust events in the Wushaoling Mountain and can also provide a scientific basis for the effective prevention of atmospheric pollution. 相似文献
17.
Soil water repellency and influencing factors of Nitraria tangutorun nebkhas at different succession stages 总被引：1，自引：0，他引：1
Soil water repellency(WR) is an important physical characteristic of soil surface. It is capable of largely influencing the hydrological and geomorphological processes of soil, as well as affecting the ecological processes of plants, such as growth and seed germination, and has thus been a hot topic in recent research around the world. In this paper, the capillary rise method was used to study the soil WR characteristics of Nitraria tangutorun nebkhas. Soil water repellencies at different succession stages of Nitraria tangutorun were investigated, and the relationships between soil WR and soil organic matter, total N, and total P, soil texture, pH, and concentrations of CO3 2-, HCO3-, Cl-, SO4 2-, Na+, K+, Ca2+and Mg2+were discussed. Soil WR may be demonstrated at the following nebkhas dune evolvement stages: extremely degradeddegradedstabilizedwell developednewly developedquick sand. Apart from some soil at the bottom, the WR of other soils(crest and slope of dune) was found to be largest at the topsoil, and decreased as the soil depth increased. The results showed that multiple factors affected soil WR characteristics, e.g. WR increased significantly as the contents of soil organic matter and total N increased, but did not change as the total P content increased. Soil texture was a key factor affecting soil WR; soil WR increased significantly as clay content increased, and decreased significantly as sand content increased. Low pH was shown to be more suitable for the occurrence of soil WR. Four cations(Ca2+, Mg2+, K+and Na+) and two anions(Cl-and SO4 2-) enhanced soil WR, while CO3 2-decreased it. HCO3-did not show any observable effect. Finally, we established a best-fit general linear model(GLM) between soil-air-water contact angle(CA) and influencing factors(CA=5.606 sand+6.496(clay and silt)–2.353 pH+470.089 CO3 2-+11.346 Na+–407.707 Cl-–14.245 SO4 2-+0.734 total N–519.521). It was concluded that all soils contain subcritical WR(0°CA90°). The development and succession of Nitraria tangutorun nebkhas may improve the formation of soil subcritical WR. There exist significant relationships between soils subcritical WR and soil physical or chemical properties. 相似文献
18.
Groundwater forms the main freshwater supply in arid and semi-arid areas,and contamination of this precious resource is complicated by the slow rate of recharge in these areas.Nitrate contamination of groundwater is a global water quality problem,as it entails threat to human health as well as aquatic ecosystems.Source identification of contamination is the cornerstone and a prerequisite for any effective management program of water quality.Stable isotope composition of the dissolved nitrate(δ15N-NO3-andδ18O-NO3-)has been applied to identify NO3-sources and the main transformation processes in the upper aquifer system(A1/2,A4,and B2/A7 aquifers)in the Wadi Shueib catchment area,Jordan.Moreover,the stable isotope compositions of the groundwater(δ2H-H2O andδ18O-H2O)in conjunction with the groundwater hydrochemistry were integrated to investigate the origin and evolution of the groundwater.Results revealed that groundwater in the study area is fresh and hard-very hard water,and mainly a Ca-Mg-Cl type.NO3-concentration was in the range of 7.0-74.0 mg/L with an average of 37.0 mg/L.Most of the samples showed concentration higher than the natural background concentration of NO3-(5.0-10.0 mg/L).Theδ2H-H2O andδ18O-H2O values indicated that the groundwater is meteoric,and of Mediterranean origin,with a strong evaporation effect.Theδ15N-NO3-values ranged between 6.0‰and 11.3‰with an average of 8.7‰,and theδ18O-NO3-values ranged between 1.6‰and 5.9‰with an average of 3.4‰.These values are in conformity with the stable isotope composition of nitrate derived the nitrification of wastewater/manure,and soil NH4.Nitrification and denitrification are the main transformation processes affecting nitrogen species.Statistical analysis revealed no significant differences in theδ2H-H2O andδ18OH2O values,andδ15N-NO3-andδ18O-NO3-values for the three aquifers(A1/2,A4,and B2/A7),indicating that the groundwater of these aquifers has the same origin,and a common source of pollution. 相似文献