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1.
Microbial production of CO2 in red soil in Stone Forest National Park   总被引:2,自引:0,他引:2  
Lunan stone forest is a kind of typical karst in China,Which is mainly developed under red soil.In the winter of 1999,three study sites were chosen in stone forest national park according to vegetation cover,geomporphologic location and soil types,CO2 concentration was measured with Gastec punp at different dephts of soil (20,40,60cm) and at the same time soil samples were gatered and soil properties such as soil moisure,pH,soil organic content were analyzed and the total nmuber of viable microbes were counted in laboratory,In the study,dependent variable was chosen as the mean soil log(PCO2),and soil properties were chosen as the independent variables.Multiple stepwise regression analysis showed that the totla amount of microbes and soil moisture are the best indicators of the CO2 production,With the equation LOG(PCO2)=-0.039(TNM)-0.056 (Mo) 1.215 accounting for 86% of the variation of the soil CO2 concentration,where TNM is the total number of microbes in teh soil and Mo is the moisture of soil sample.  相似文献   

2.
Lunan stone forest is a kind of typical karst in China, which is mainly developed underred soil. In the winter of 1999, three study sites were chosen in stone forest national park accordingto vegetation cover, geomorphologic location and soil types. CO2 concentration was measured withGastec pump at different depths of soil (20, 40, 60 cm) and at the same time soil samples weregathered and soil properties such as soil moisture, pH, soil organic content were analyzed and thetotal number of viable microbes were counted in laboratory. In the study, dependent variable waschosen as the mean soil log (PCO2), and soil properties were chosen as the independent variables.Multiple stepwise regression analysis showed that the total amount of microbes and soil moisture arethe best indicators of the CO2 production, with the equation LOG(PCO2) = - 0.039(TNM) - 0.056(Mo) + 1.215 accounting for 86% of the variation of the soil CO2 concentration, where TNM is thetotal number of microbes in the soil and Mo is the moisture of soil sample.  相似文献   

3.
Throughfall, stemflow, evapotranspiration and infiltration are likely to vary with forest types, and consequently affect soil moisture regimes in different soil layers. In this study, the spatial and temporal characteristics of soil moisture were investigated to understand variations in soil moisture in three typical forests, including Phyllostachys pubescens forest (abbreviated as PPF), Schima superba forest (abbreviated as SSF) and Cunninghamia lanceolata forest (abbreviated as CLF) in the upper reaches of Lijiang River basin in southern China. The results showed that, (1) Litterfall and soil physical properties differed significantly in the three typical forests. Infiltration capacity in SSF was more favorable to soil moisture than in PPF and CLF. (2) Large variations were found in soil moisture at different forest stands and depths. Due to complicated vertical structures, there were obvious differences in soil moisture from the 0-20 cm soil layer to the 50-80 cm soil layer. (3) Average soil moisture in each layer was higher in SSF than in PPF and CLF. (4) Soil moisture in different layers correlated closely with precipitation (P<0.01) and the three typical forests had the same change trends with rainfall during the studying period. (5) In topsoil, soil moisture was influenced by soil properties which were mostly determined by litterfall, while in deep soil, soil moisture was affected by variations of soil characteristics, which were mostly determined by root distribution. This study provides a scientific basis for better understanding the relationships between forest vegetation and its hydrological effects, helping to facilitate water resources conservation and achieving wise forest management in the upper reaches of Lijiang River basin.  相似文献   

4.
利用开路式土壤碳通量测量系统-LI-8100对塔里木河下游6种土地利用方式下土壤呼吸速率的日变化进行了野外定位测量,并就水热因子及土壤理化性质对土壤日呼吸速率差异的影响进行了分析。结果表明,梨园、弃耕地、棉田、人工林、草地和天然林土壤呼吸速率日变化均呈单峰曲线,土壤日呼吸速率差异显著。大气温度和土地利用方式是造成土壤日呼吸差异的主要因素,其中土地利用方式通过改变地表温度、土壤水分、电导率、pH、盐分含量及机械组成等影响土壤日呼吸速率。  相似文献   

5.
Coastal sand dune ecosystems generally have infertile soil with low water-holding capacity and high salinity. However, many plant species have adapted to the harsh sand environment along the southeastern coast of China. Studying the microbial biomass in such an ecosystem can improve our understanding of the roles that microbes play in soil fertility and nutrient cycling. We investigated the differences in soil microbial biomass carbon (MBC) and nitrogen (MBN) contents and their seasonal dynamics in five forest types (a secondary forest and plantations of Casuarinas, Pine, Acacia, and Eucalyptus). The results indicated that the seasonal variations of soil MBC and MBN contents in all five forest stands were higher in spring and winter, but lower in summer and autumn. The MBC content was lower in the Casuarinas plantation than in the other plantations in the same soil layer. However, no significant differences were observed in MBN contents among the different forest types. The MBC and MBN concentrations were positively correlated with soil moisture, but negatively correlated with soil temperature. The MBC and MBN contents also decreased with increasing soil depth. Across all soil layers, secondary forest had the highest MBC and MBN concentrations. Our study also showed that the MBC and MBN contents were positively affected by total soil carbon (TC), pH, and litter N content, but were negatively impacted by soil bulk density and litter C content. Moreover, the MBN content was positively correlated with root N content. In summary, environmental factors and the differences in litter and fine roots, soil nutrient contents, as well as the soil physical and chemical properties caused by different tree species collectively affected the concentrations of the soil MBC and MBN.  相似文献   

6.
黄磊  张志山  胡宜刚  张鹏  赵洋 《中国沙漠》2012,32(6):1583-1589
对固沙植被区典型分布的藻类结皮、藓类结皮和流沙下不同深度的土壤气体采样,主要研究和讨论了不同类型生物土壤结皮下土壤CO2浓度的变化特征,及土壤温度和土壤水分对它的影响。结果表明,藻类结皮和藓类结皮在0~40 cm处的土壤空气CO2浓度平均值基本保持在600~1 100 μmol·mol-1之间,大于同一深度流沙下土壤CO2浓度值,但三者之间的差异并不显著。土壤温度与土壤CO2浓度呈正相关关系,且在表层相关性最强,具体表现为流沙>藓类结皮>藻类结皮。土壤水分对土壤CO2浓度的影响在表层0~5 cm为流沙>藻类结皮>藓类结皮,但在下层10~40 cm处为藻类结皮>藓类结皮>流沙。  相似文献   

7.
腾格里沙漠东南缘固沙灌丛林土壤理化性质及分形维数   总被引:2,自引:1,他引:1  
以腾格里沙漠固沙灌丛林为研究对象,选择大、中、小沙丘的迎风坡、丘顶和背风坡为研究样地,调查不同沙丘微地形土壤理化性质和土壤粒径分布的分形特征,阐明沙丘大小和微地形差异对固沙灌丛林土壤理化性质和土壤分形维数分布的影响规律。结果表明:(1)土壤含水率和全碳含量均表现为背风坡中部显著高于丘顶;土壤容重表现为迎风坡中部、丘顶和背风坡底部显著高于背风坡中部,而迎风坡底部居中;沙丘微地形对土壤pH和电导率均无显著影响。土壤容重表现为大、中沙丘显著高于小沙丘;土壤电导率表现为中、小沙丘显著高于大沙丘;沙丘大小对土壤含水率、pH和全碳分布均无显著影响。(2)土壤粉粒(2—50 μm)含量表现为迎风坡底部>背风坡底部>迎风坡中部>丘顶,而土壤极细砂(50—100 μm)含量表现为背风坡底部显著低于迎风坡中部和丘顶,土壤细砂(100—250 μm)含量表现为丘顶显著高于迎风坡底部和中部。大、中沙丘土壤颗粒组成以土壤粉粒和极细砂为主,而小沙丘则以土壤细砂为主。(3)土壤分形维数介于2.59—2.78,表现为迎风坡底部显著高于背风坡底部,其他3个微地形生境居中,而且大沙丘显著高于中沙丘,而小沙丘居中。(4)粉粒含量越高,土壤电导率和全碳含量越高;极细砂含量越高,土壤电导率越低;砂粒含量越高,全碳含量越低;土壤细砂含量越多,分形维数越大。沙丘大小、微地形对土壤理化性质及分形维数的作用效果存在较大的差异性,需要根据沙丘大小和微地形来开展人工林建设和生态效应评价。  相似文献   

8.
长白山天然次生白桦林土壤CO_2释放通量研究   总被引:2,自引:0,他引:2  
利用静态箱/气相色谱法测定了长白山天然次生白桦林土壤二氧化碳释放通量.在生长季节的春、夏、秋三个时间段对白桦林土壤CO2释放通量测定的结果表明:白桦林土壤呼吸的日变化和不同生长季节的变化均与温度的变化有明显的相关性.白昼的土壤CO2的释放通量始终高于夜晚,但白昼土壤CO2释放通量的峰值与气温的峰值相比具有一定的滞后性.土壤CO2释放通量夏季明显高于春秋两季,凋落物层对土壤CO2释放具有一定的影响,夏季去除凋落物层后土壤CO2释放通量高于未除凋落物层时CO2释放通量,而春秋两季则出现相反的结果.通过相关分析发现,有凋落物覆盖的土壤CO2释放通量与地下5cm温度相关性最好,而去除凋落物后土壤CO2释放通量则与地表温度相关性最高.  相似文献   

9.
黄土高原半干旱区天然锦鸡儿灌丛对土壤水分的影响   总被引:13,自引:4,他引:13  
本文选择黄土高原半干旱区定西地区的一种地带性植被,天然甘蒙锦鸡儿灌丛,将其0~99m深的土壤水分含量与人工柠条锦鸡儿灌丛、人工杏树林、天然草地、放牧荒坡和农地的土壤水分含量进行了比较。结果发现,天然锦鸡儿灌丛在1m以下土壤各层的水分含量均高于人工柠条灌丛和人工杏树林,而与放牧荒坡和农地的土壤湿度接近,略低于农地。天然锦鸡儿灌丛4m以上土层的土壤湿度还明显高于天然草地;天然锦鸡儿灌丛形成的难效—无效水层深度在2m土层以上,而人工柠条灌丛形成的难效无效水层则深达56m,人工杏树林42m,天然草地、放牧荒坡分别为36m和33m,农地1m。  相似文献   

10.
黄蓉  王辉  王蕙  南耀明  赵赫然  段雅楠 《中国沙漠》2013,33(6):1782-1788
为探讨华家岭低效防护林带改造对土壤的改良效果,在华家岭地区选取生长不良的低效杨树纯林和改造后的云杉纯林、云杉×杨树、云杉×油松、云杉×落叶松混交林5种典型林带类型,对其土壤理化性状进行对比研究。结果表明:(1)云杉纯林及其混交林土壤的平均容重、平均毛管孔隙度、总孔隙度、通气度与杨树纯林的差异显著(p<0.05),经过低效林改造后的云杉纯林及其混交林较杨树纯林的土壤容重有所下降,孔隙度和通气性有所提高\.(2)除速效P外,各林型的土壤速效N、速效K、全N、全P、全K和有机质含量随土层深度的增加而降低;云杉纯林及其混交林的土壤有机质含量、速效N、P、K和全量N、P、K养分均高于杨树纯林,pH值低于杨树纯林\.(3)云杉纯林及其混交林的有机质含量和全N含量与容重和总孔隙度的相关性较杨树纯林的好,云杉纯林及其混交林对土壤理化性能的改良作用优于杨树纯林。  相似文献   

11.
陕西咸阳人工林地土壤干层研究   总被引:20,自引:4,他引:16  
赵景波  杜娟  周旗  岳应利 《地理科学》2005,25(3):322-328
根据咸阳庞西村苹果林地、梧桐林地和草地土壤含水量测定,研究了0~6m土壤含水量的变化和土壤干层特点与分布。结果显示, 咸阳人工林地从表层向下含水量呈现由高到低再到低的变化;10龄苹果林地2~4m深处土壤含水量平均为8.3%,12龄梧桐林2~4m深处土壤含水量平均为8.6%,均发育了明显的土壤干层;4龄苹果林下土层有干化显示,但无干层发育;草地土层含水量明显较苹果林地高,无土壤干化的显示。研究表明,土壤干层形成的具体原因一是降水量少决定的薄膜水带埋藏深度小,二是薄膜水的运移速度缓慢和含水量低。为保持人工林基本正常的生长和土壤水的正常运移,应避免严重的土壤干层出现。咸阳附近土壤干层的出现表明土壤干层在黄土高原广泛分布,该区的植被恢复首先应以疏林或森林草原为主,待土壤水分改善后再考虑恢复森林植被。  相似文献   

12.
Based on the static opaque chamber method, the respiration rates of soil microbial respiration, soil respiration, and ecosystem respiration were measured through continuous in-situ experiments during rapid growth season in semiarid Leymus chinensis steppe in the Xilin River Basin of Inner Mongolia, China. Soil temperature and moisture were the main factor affecting respiration rates. Soil temperature can explain most CO2 efflux variations (R2=0.376–0.655) excluding data of low soil water conditions. Soil moisture can also effectively explain most of the variations of soil and ecosystem respiration (R2=0.314–0.583), but it can not explain much of the variation of microbial respiration (R2=0.063). Low soil water content (≤5%) inhibited CO2 efflux though the soil temperature was high. Rewetting the soil after a long drought resulted in substantial increases in CO2 flux at high temperature. Bivariable models based on soil temperature at 5 cm depth and soil moisture at 0–10 cm depth can explain about 70% of the variations of CO2 effluxes. The contribution of soil respiration to ecosystem respiration averaged 59.4%, ranging from 47.3% to 72.4%; the contribution of root respiration to soil respiration averaged 20.5%, ranging from 11.7% to 51.7%. The contribution of soil to ecosystem respiration was a little overestimated and root to soil respiration little underestimated because of the increased soil water content that occurred as a result of plant removal.  相似文献   

13.
Nitrous oxide(N_2 O) is one of the most important greenhouse gases in the atmosphere; freeze–thaw cycles(FTCs) might strongly influence the emission of soil N_2 O on the Qinghai–Tibetan Plateau(QTP). However, there is a lack of in situ research on the characteristics of soil N_2 O concentration and flux in response to variations in soil properties caused by FTCs.Here, we report the effect of FTC-induced changes in soil properties on the soil N_2 O concentration and flux in the permafrost region of the higher reaches of the Shule River Basin on the northeastern margin of the QTP. We measured chemical properties of the topsoil, activities of soil microorganisms, and air temperature(AT), as well as soil N_2 O concentration and flux, over an annual cycle from July 31, 2011, to July 30, 2012. The results showed that soil N_2 O concentration was significantly affected by soil temperature(ST), soil moisture(SM), soil salinity(SS), soil polyphenol oxidase(SPO), soil alkaline phosphatase(SAP), and soil culturable actinomycetes(SCA), ranked as SMSSSTSPOSAPSCA, whereas ST significantly increased soil N_2 O flux, compared with SS. Overall, our study indicated that the soil N_2 O concentration and flux in permafrost zone FTCs were strongly affected by soil properties, especially soil moisture, soil salinity, and soil temperature.  相似文献   

14.
在南极菲尔德斯半岛进行了微生物总菌量的调查。共收集样品35个(以土壤样品为主),从这些样品中计数得到一般细菌总量范围为:103-106cels/g(30°C),104-106cels/g(16°C),104-106cels/g(4°C);一般真菌总量范围为:102-103cels/g(30°C),102-103cels/g(16°C),103cels/g(4°C)。初步鉴定细菌有7个属:微球菌属,葡萄球菌属,节细菌属,黄杆菌属,产碱菌属,假单胞菌属,芽孢杆菌属。真菌有5个属:青霉菌属,金孢霉菌属,枝孢霉菌属,曲霉菌属,散子囊菌属。特别是在绝大多数样品中4°C下培养的一般细菌与真菌总量明显高于30°C下培养的菌量,同时离半岛海岸线近的地区菌量也高于半岛内陆地区的菌量。在该地区,4°C下培养的低温菌出现率主要是假单胞菌属(69%),芽孢杆菌属(54%),青霉菌属(46%),曲霉菌属(17%)。  相似文献   

15.
Liu  Muxing  Wang  Qiuyue  Guo  Li  Yi  Jun  Lin  Henry  Zhu  Qing  Fan  Bihang  Zhang  Hailin 《地理学报(英文版)》2020,30(6):949-968
Rainfall provides essential water resource for vegetation growth and acts as driving force for hydrologic process, bedrock weathering and nutrient cycle in the steep hilly catchment. But the effects of rainfall features, vegetation types, topography, and also their interactions on soil water movement and soil moisture dynamics are inadequately quantified. During the coupled wet and dry periods of the year 2018 to 2019, time-series soil moisture was monitored with 5-min interval resolution in a hilly catchment of the Three Gorges Reservoir Area in China. Three hillslopes covered with evergreen forest(EG), secondary deciduous forest mixed with shrubs(SDFS) and deforested pasture(DP) were selected, and two monitoring sites with five detected depths were established at upslope and downslope position, respectively. Several parameters expressing soil moisture response to rainfall event were evaluated, including wetting depth, cumulative rainfall amount and lag time before initial response, maximum increase of soil water storage, and transform ratio of rainwater to soil water. The results indicated that rainfall amount is the dominant rainfall variable controlling soil moisture response to rainfall event. No soil moisture response occurred when rainfall amounts was 8 mm, and all the deepest monitoring sensors detected soil moisture increase when total rainfall amounts was 30 mm. In the wet period, the cumulative rainfall amount to trigger surface soil moisture response in EG-up site was significantly higher than in other five sites. However, no significant difference in cumulative rainfall amount to trigger soil moisture response was observed among all study sites in dry period. Vegetation canopy interception reduced the transform ratio of rainwater to soil water, with a higher reduction in vegetation growth period than in other period. Also, interception of vegetation canopy resulted in a largeraccumulated rainfall amount and a longer lag time for initiating soil moisture response to rainfall. Generally, average cumulative rainfall amount for initiating soil moisture response during dry period of all sites(3.5–5.6 mm) were less than during wet period(5.7–19.7 mm). Forests captured more infiltration water compared with deforested pasture, showing the larger increments of both soil water storage for the whole soil profile and volumetric soil water content at 10 cm depth on two forest slopes. Topography dominated soil subsurface flow, proven by the evidences that less rainfall amount and less time was needed to trigger soil moisture response and also larger accumulated soil water storage increment in downslope site than in corresponding upslope site during heavy rainfall events.  相似文献   

16.
土壤呼吸不仅是反映土壤生物活性的重要指标,也是全球碳循环研究中备受关注的热点问题。在地处典型干旱区的石羊河下游,以流动沙丘和去除土壤结皮人工梭梭林为对照,采用LI-8100土壤碳通量监测系统研究了栽植约40 a、30 a、10 a和5 a的人工梭梭林生长季和非生长季的土壤呼吸日变化,并分析了土壤水分和温度对土壤呼吸的影响。结果表明:(1)不同林龄梭梭林生长季和非生长季土壤呼吸速率的日变化均为明显的单峰曲线,且呈现出一定的波动性,日最大排放速率出现在12:00~14:00时,最小值出现在8:00时左右。(2)梭梭林营造和去结皮处理显著提高了沙漠土壤呼吸速率,而且不同林龄土壤呼吸速率大体上随着种植年限的增加而递增,表现为MC >40 a>30 a>10 a>MS >5 a,非生长季表现为MC >40 a>10 a>5 a>30 a>MS。(3)不同林龄梭梭林土壤呼吸速率均具有明显的季节变化特征,生长季(8 月)的土壤呼吸作用明显强于非生长季(1月)。(4)相关性分析表明,生长季和非生长季土壤呼吸均与0~5 cm土壤水分显著相关,且均呈二次曲线关系,分别为Y =-0.205 8X 2+0.946 5X-0.316 6(R 2 =0.506 2P= 0.041 7)和Y= 0.118 7 X 2+0.156 3X+0.118 8(R 2=0.675 7,P =0.001 1);但与10 cm土壤温度的相关性不显著,土壤水分是影响人工梭梭林土壤呼吸的关键因素。该研究进一步证明了人工梭梭林的营造有效改善了沙漠土壤的生物活性,提高了土壤碳通量水平,以土壤结皮破坏为基本特征的人工梭梭林退化和沙漠化必然在短期内加剧碳排放。因此,需要在沙漠地区合理营造人工林,并在造林和林业管理过程中注意保护土壤结皮,以减少CO2排放。  相似文献   

17.
Understanding the temperature and moisture sensitivity of soil organic matter (SOM) mineralization variations with changes in land cover is critical for assessing soil carbon (C) storage under global change scenarios. We determined the differences in the amount of SOM mineralization and the temperature and moisture sensitivity of soils collected from six land-cover types, including an orchard, a cropland, and four forests, in subtropical southeastern China. The responses of SOM mineralization to temperature (5, 10, 15, 20, and 25°C) and moisture (30%, 60%, and 90% of water-holding capacity [WHC]) were investigated by placing soil samples in incubators. Soil C mineralization rate and cumulative C mineralization were higher in orchard and cropland soils than in other forest soils. With increasing temperature, soil C mineralization rates and cumulative C mineralization increased with the rise of WHC. The temperature sensitivity of soil C mineralization was not affected by land-cover type and incubation moisture. All soil temperature treatments showed a similar response to moisture. Cropland soil was more responsive to soil moisture than other soils. Our findings indicate that cropland and orchard soils have a higher ability to emit CO2 than forest soils in subtropical southeastern China.  相似文献   

18.
于2016年7~12月和2017年4月的旱、雨季期间,以金沙江干热河谷苴那小流域内的银合欢(Leucaena Benth)林地、车桑子(Dodonaea angustifolia)灌丛地和扭黄茅(Heteropogon cantortus)草地为研究对象,通过网格法和土钻法采集并测定了(0~100 cm)土层的土壤含水量,应用经典统计法和地统计学方法分析该区域不同林草植被下坡面土壤水分的动态变化特征。结果表明:(1)研究区土壤含水量总体较低,雨季显著大于旱季,旱、雨季均表现为灌丛地>草地>林地,呈中度至强度变异(0.07~0.28之间)。(2)不同林草植被下旱、雨季土壤水分具有相似的空间自相关性,自相关系数均由正向负转变,但由正向负转变的滞后距离有所不同,且雨季大于旱季,呈中等或强等空间自相关性。(3)不同林草植被下的土壤水分空间结构不同,林地、灌丛地和草地旱雨季最佳拟合模型均为球状模型;相同林草植被下各土层旱、雨季土壤水分的空间分布特征相似,但旱季的分布格局差异更显著,不同林草植被下深层土壤水分分布比表层土壤水分的分布更为复杂,土壤水分呈明显的斑块或条带状分布,含水量高值区和低值区位置不固定。总之不同林草植被类型会改变局部地段土壤水分空间分布,降雨会加强这种差异的趋势,但土壤水分仍具一定空间连续性。  相似文献   

19.
为了研究不同土壤CO2浓度和不同土壤水化学条件下的岩溶作用发生程度,文章对广西桂林地区的土壤CO2浓度、土壤水和石灰岩试片溶蚀速率进行了监测,结果表明:1)该地区土壤CO2浓度具有明显的季节性变化特征,总体上夏季是其他季节的3~5倍,最大值时达到60 899.64 mg/m2,而最小值时仅为5 587.21 mg/m2;2)就相同深度的土壤CO2浓度来说,洼地大于坡地,夏季时洼地比坡地高近20 000 mg/m2,且深层土CO2浓度大于表层土,其平均值比表层土高4 353.54 mg/m2;3)坡地和洼地土壤水水化学指标平均值分别是:pH为7.49和6.41、电导率为300和78 μS/cm、Ca2+为60和15.43 mg/L、 为2.78和0.44 mg/L,坡地处的pH、电导率、Ca2+和 均高于洼地;4)从溶蚀试验说明该地区的岩溶作用发生程度非常明显,说明土壤CO2和土壤水能驱动岩溶作用的发生。  相似文献   

20.
土壤呼吸的微小变化会对大气CO2浓度产生重大影响,尤其在极端干旱区。通过对黑河下游额济纳旗四道桥的混合林、胡杨、柽柳、农田及裸地的土壤呼吸进行研究,结果表明:2014 年夏季5 种不同植被类型的土壤呼吸速率大小排序:胡杨柽柳混合林 > 柽柳 > 农田 > 胡杨 > 裸地,各类型的5 cm处土壤温度和湿度无明显变化规律,土壤温度在22~35 ℃,土壤湿度集中在13%~61%的变化范围。探究了5 种不同植被类型的土壤呼吸速率与土壤温度、土壤湿度、地表温度、空气温度及空气湿度的线性相关关系,发现它们的土壤呼吸速率与土壤温度、土壤湿度、空气温度、空气湿度之间无显著相关(P>0.05),表明水热因子对土壤呼吸的影响具有很大的不确定性。  相似文献   

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