黑色地膜对马铃薯产量及土壤质量的影响     

周丽敏  张皓  李琪  韩媛  谢佳 《南京气象学院学报》2016,8(4):316-321

在半湿润的南京地区,以微型马铃薯荷兰七号为指示作物,采用平地起垄覆膜的种植方式,分别选用黑色地膜（BM）与普通白色地膜（WM）做比较,并以不覆膜的平地作为对照（CK）,分析不同处理对微型马铃薯生理指标、产量以及种植区土壤质量的影响.发现BM处理下微型马铃薯的淀粉质量分数和产量最高,较WM处理增产31.1%,较CK增产43.7%;覆膜处理显著降低了耕层土壤的速效钾质量分数,BM处理下耕层土壤的速效磷质量分数最低,但土壤铵态氮与硝态氮质量分数显著高于其他处理;覆膜处理有效提高了微型马铃薯出苗期的耕层土壤含水量,BM处理下微型马铃薯生育期内的表层土壤温度明显低于WM,且高于对照,对微型马铃薯的生长更有利.  相似文献   

Radiative Forcing and Climate Response Due to Black Carbon in Snow and Ice     

WANG Zhili  ZHANG Hu  SHEN Xueshun 《大气科学进展》2011,28(6):1336-1344

The radiative forcing and climate response due to black carbon(BC) in snow and/or ice were investigated by integrating observed effects of BC on snow/ice albedo into an atmospheric general circulation model(BCC AGCM2.0.1) developed by the National Climate Center(NCC) of the China Meteorological Administration(CMA).The results show that the global annual mean surface radiative forcing due to BC in snow/ice is +0.042 W m 2,with maximum forcing found over the Tibetan Plateau and regional mean forcing exceeding +2.8 W m 2.The global annual mean surface temperature increased 0.071 C due to BC in snow/ice.Positive surface radiative forcing was clearly shown in winter and spring and increased the surface temperature of snow/ice in the Northern Hemisphere.The surface temperatures of snow-covered areas of Eurasia and North America in winter(spring) increased by 0.83 C(0.6 C) and 0.83 C(0.46 C),respectively.Snowmelt rates also increased greatly,leading to earlier snowmelt and peak runoff times.With the rise of surface temperatures in the Arctic,more water vapor could be released into the atmosphere,allowing easier cloud formation,which could lead to higher thermal emittance in the Arctic.However,the total cloud forcing could decrease due to increasing cloud cover,which will offset some of the positive feedback mechanism of the clouds.  相似文献   

Variation of particulate organic carbon and its relationship with bio-optical properties during a phytoplankton bloom in the Pearl River estuary   总被引：2，自引：0，他引：2  

Wang G  Zhou W  Cao W  Yin J  Yang Y  Sun Z  Zhang Y  Zhao J 《Marine pollution bulletin》2011,62(9):1939-1947

In this study, variations in the particulate organic carbon (POC) were monitored during a phytoplankton bloom event, and the corresponding changes in bio-optical properties were tracked at one station (114.29°E, 22.06°N) located in the Pearl River estuary. A greater than 10-fold increase in POC (112.29-1173.36 mg m⁻³) was observed during the bloom, with the chlorophyll a concentration (Chl-a) varying from 0.984 to 25.941 mg m⁻³. A power law function is used to describe the relationship between POC and Chl-a, and the POC:Chl-a ratio tends to change inversely with Chl-a. Phytoplankton carbon concentration is indirectly estimated using the conceptual model proposed by Sathyendranath et al. (2009), and this carbon is found to contribute 47.21% (±10.65%) to total POC. The estimated carbon-to-chlorophyll ratio of phytoplankton in diatom-dominated waters is found to be comparable with results reported in the literature. Empirical algorithms for determining the concentrations of Chl-a and POC were developed based on the relationships of these variables with the blue-to-green reflectance ratio. With these bio-optical models, the levels of particulate organic carbon and Chl-a could be predicted from the radiometric data measured by a marine optical buoy, which showed much more detailed information about the variability in biogeochemical parameters during this bloom event.  相似文献   

Effects of nitrogen and phosphorus on phytoplankton composition and biomass in 15 subtropical, urban shallow lakes in Wuhan, China   总被引：6，自引：0，他引：6  

Jin LvHongjuan Wu  Mengqiu Chen 《Limnologica》2011,41(1):48-56

This study aims at investigating the composition and biomass of the phytoplankton community in 15 urban shallow eutrophic lakes as well as the effects of main environmental factors, including nutrient concentrations and the ratio of nitrogen to phosphorus, temperature, COD, BOD, water depth, etc. on the phytoplankton community structure. Lake water samples were taken and analyzed on a bimonthly basis during the period from March 2004 to March 2006. The redundancy analysis (RDA) and regression analysis (RA) were performed to identify the effects of nutrients on the phytoplankton community and biomass in these typical urban lakes. The results indicate that most of these urban lakes were hypertrophic due to high concentrations of total phosphorus (TP) and total nitrogen (TN), with mean levels of 490 and 5380 mg m⁻³, respectively. The phytoplankton community was dominated by Microcystis aeruginosa and Euglena caudate in summer and Cryptomonas ovata and Cyclotella meneghiniana in winter. The mean biomass of the phytoplankton reached 456.87 mg L⁻¹ in summer months and the annual level was 189.24 mg L⁻¹. Temperature and TP content were found to be the principal limiting factors for phytoplankton growth on an annual basis. On the other hand, the results of RDA and RA demonstrate that the dominant phytoplankton species were not nutrient-limited during summer months. Low TN:TP ratios (<10) were detected accompanied with fewer occurrences of N-fixing cyanobacteria and other filamentous algae in most lakes in summer, which implies that low N:P ratio does not always shifts the dominance of phytoplankton community to the N-fixing cyanobacteria. Moreover, TP always had higher correlation with chlorophyll a (Chl-a) than TN, even when the TN:TP ratios of most samples were lower than 10. Therefore, it is concluded that the TN:TP ratio is not always a suitable index to determine whether nitrogen or phosphorus limits the phytoplankton biomass in urban shallow eutrophic lakes.  相似文献   

Dynamics of dissolved organic carbon after a cyanobacterial bloom in hypereutrophic Lake Taihu (China)   总被引：5，自引：0，他引：5  

Linlin Ye  Xiao Shi  Xiaodong Wu  Min Zhang  Yang Yu  Daming Li  Fanxiang Kong 《Limnologica》2011,41(4):382-388

To establish the influence of the cyanobacterial bloom collapse on the characteristics of dissolved organic carbon (DOC) in Lake Taihu, high-molecular-weight dissolved organic matter (HMW-DOM), with sizes between 1 kDa and 0.5 μm, were collected using cross-flow ultrafiltration, from three different eutrophic regions. Isolated HMW-DOM was further characterized by atomic carbon to nitrogen ratio and neutral sugars composition by gas chromatography and mass spectrometry. The results indicated that the cyanobacterial cell lysis induced by nitrate depletion is the likely mechanism for DOC release. The relatively high DOC level was associated with the high chlorophyll a concentration in Meiliang Bay, one of the most eutrophic bays in the northern part of the lake. However, no significant correlations were observed between chlorophyll a concentration and HMW-DOC concentration during the demise of the cyanobacterial bloom in Lake Taihu. No significant differences were found in the HMW-DOC concentration among the three sampling sites, which were selected to represent different eutrophic status. However, a significant difference in the HMW-DOC concentration was found between October 2009 and January 2010 in all three sampling sites (p = 0.02). The HMW-DOC release may be attributed to the cyanobacterial cell lysis after the peak of summer bloom. The similarity in neutral sugar composition between the HMW-DOM and cyanobacterial exopolysaccharides suggests that the cyanobacterial bloom is the source of HMW-DOM. However, the significant correlation between the carbon to nitrogen ratio in HMW-DOM and chlorophyll a concentration was only observed in Meiliang Bay, which implies that apart from the cyanobacteria-derived DOC, a fraction of DOC was from riverine input. The decline of the cyanobacterial bloom also changed the overall DOM pool, leading to a shift in the component of HMW-DOM from a C-enriched material to an N-enriched material, as revealed by the variation in the carbon to nitrogen ratios. Overall, these results demonstrate that the quantitative and qualitative DOM is affected by the post-cyanobacterial bloom in Lake Taihu.  相似文献   

基于MODIS植被指数的太湖蓝藻信息提取方法研究   总被引：4，自引：1，他引：3  

李亚春  孙佳丽  谢志清  谢小萍 《气象科学》2011,31(6):737-741

有效地提取蓝藻水华信息对分析蓝藻动态分布有重要意义,而卫星遥感技术是进行太湖水质监测与保护的措施之一.本文以2007年7月25日Terra/MODIS数据为主要数据源,用比值植被指数(Irv)、归一化植被指数(Indv)和增强型植被指数(Iev),研究提取太湖蓝藻信息.结果表明:植被指数可以有效提取遥感影像中的蓝藻水华信息,其中Indv是应用效果较好的植被指数之一;在掩膜处理后,用Indv提取了太湖蓝藻的面积分布信息,效果较好;此外,选取Indv为测试变量,利用决策树分类法,有效地把蓝藻水华高浓度覆盖区、中浓度覆盖区和轻浓度覆盖区分开来,为准确掌握太湖蓝藻发生、发展趋势和发生程度提供可靠信息.  相似文献   

Inter- and intra-annual patterns of Ulva prolifera green tides in the Yellow Sea during 2007-2009, their origin and relationship to the expansion of coastal seaweed aquaculture in China   总被引：2，自引：0，他引：2  

Keesing JK  Liu D  Fearns P  Garcia R 《Marine pollution bulletin》2011,62(6):1169-1182

The large green-tide events that occurred in the Yellow Sea in 2008 (3489 km²) and 2009 (4994 km²) are shown to be novel events preceded only once by a much smaller event in 2007 (82 km²). The blooms originated in the coastal area of Jiangsu province and spread north-east towards the Shandong Peninsula. The blooms grew at different rates and mesoscale variability in surface winds explained the differences in the spatial and temporal patterns of blooms in 2008 and 2009. The 2009 bloom was tracked to its origin immediately offshore of extensive intertidal flats between Yancheng and Nantong where recent rapid expansion of Porphyra aquaculture has occurred. We review published hypotheses which have been advanced to explain the occurrence of blooms and in light of our findings, we conclude that the accumulation and disposal of waste Ulva prolifera from Porphyra aquaculture rafts is the most likely cause of the blooms.  相似文献   

钼及钼同位素地球化学——同位素体系、测试技术及在地质中的应用   总被引：2，自引：2，他引：0  

徐林刚  Bernd Lehmann 《矿床地质》2011,30(1):103-124

多接收电感耦合等离子体质谱(MC-ICP-MS)的广泛应用使过渡金属元素同位素地球化学的研究近年来获得蓬勃发展.利用元素双稀释剂法对钼同位素值进行校正,目前可以获得±0.1‰(2σ)的测试精度.自然界中钼同位素分馏δ98/95Mo可达～3‰,其分馏机制与环境的氧化-还原状态有关.在氧化环境下钼以MoO2/4-的形式与锰...  相似文献   

黑洞的搜寻和证认(I):现状     

张冰  乔国俊  韩金林 《天文学进展》1998,(4)

简要介绍有关黑洞的理论及其表现形式,详细综述在星系中心及X射线双星中搜寻和证认黑洞的原理、方法及现状．在星系层次,除活动星系核中心可能存在的黑洞外,在邻近星系中已找到至少11个黑洞候选者,但观测所及的最小尺度仍比黑洞视界高几个量级。在恒星层次,利用动力学判据,人们己在大质量X射线双星和软X射线暂现源中找到至少10个强候选者,并利用辐射判据找到更多的候选者,但目前仍然没有找到黑洞双星区别于中子星双星的决定性判据．所有这些说明,迄今尚未找到充足的证据证明黑洞的存在。  相似文献   

Application of Re-Os Geochemistry to Sedimentary Basin: Stratigraphic Correlation, Oil - Source Correlation and Paleo-Environment Condition     

XU Guangping  Judith L. Hannah  Holly J. Stein  Svetoslav Georgiev 《《地质学报》英文版》2013,87(Z1):602-604

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