Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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Retrieval of CDOM and DOC Using In Situ Hyperspectral Data: A Case Study for Potable Waters in Northeast China
No full textChromophoric dissolved organic matter (CDOM), the light absorbing fraction of dissolved organic carbon (DOC), together with phytoplankton and total suspended matter are the main optically active components could be retrieved by remote sensing data. Generally, different composition of DOC and CDOM corresponds to different water surface reflectance. Absorption properties of CDOM and retrieval models for CDOM and DOC were investigated with data from potable reservoirs located in the central of Jilin Province. Water sampling field surveys were conducted on 15, 16 and 19 of September 2012 across the Shitoukoumen, Erlonghu and Xilicheng reservoirs, respectively. Both empirical regression (single band model and band ratio model) and partial least squares coupled with back-propagation artificial neural models (PLSBPNN) were established to estimate CDOM absorption coefficient at 355 nm [a(CDOM)(355)] and DOC concentration with in situ measured remote sensing reflectance. It was found that the band ratio models and PLSBPNN model performed well for estimating DOC concentration while the band ratio models yielded the best result in retrieval CDOM. Moreover, all the three models performed better on the DOC concentration estimation than the performance on a(CDOM)(355). Band ratio models outperformed (R (2) = 0.55) other models for estimating CDOM absorption coefficient, while PLSBPNN model outperformed other models with respect to DOC estimation (R (2) = 0.93). High spectral slope values indicated that CDOM in the potable waters primarily comprised low molecular weight organic substances; while sources of DOC were mainly coming from exogenous input, which was the main reason lead to the difference of model performances on DOC and a(CDOM)(355) estimation. The algorithms developed in this study is needed to be tested and refined with more in situ spectral data, also future work is still needed to be undertaken for characterizing the dynamic of the potable water quality with remotely sensed imagery
Identification of additional QTLs for flowering time by removing the effect of the maturity gene E1 in soybean
No full textThe adaptability of soybean to be grown at a wide range of latitudes is attributed to natural variation in the major genes and quantitative trait loci (QTLs) that control flowering time and maturity. Thus, the identification of genes controlling flowering time and maturity and the understanding of their molecular basis are critical for improving soybean productivity. However, due to the great effect of the major maturity gene E1 on flowering time, it is difficult to detect other small-effect QTLs. In this study, aiming to reduce the effect of the QTL, associated with the E1 gene, on the detection of other QTLs, we divided a population of 96 recombinant inbred lines (RILs) into two sub-populations: one with the E1 allele and another with the e1nl allele. Compared with the results of using all 96 recombinant inbred lines, additional QTLs for flowering time were identified in the sub-populations, two (qFT-B1 and qFT-H) in RILs with the E1 allele and one (qFT-J-2) in the RILs with the e1nl allele, respectively. The three QTLs, qFT-B1, qFT-H and qFT-J-2 were true QTLs and played an important role in the regulation of growth period. Our data provides valuable information for the genetic mapping and gene cloning of traits controlling flowering time and maturity and will help a better understanding of the mechanism of photoperiod-regulated flowering and molecular breeding in soybean
A ubiquitous knowledgeable data representation model (UKRM) for three-dimensional geographic information systems (3D GIS)
No full textIn the face of complicated, diversified three-dimensional world, the existing 3D GIS data models suffer from certain issues such as data incompatibility, insufficiency in data representation and representation types, among others. It is often hard to meet the requirements of multiple application purposes (users) related to GIS spatial data management and data query and analysis, especially in the case of massive spatial objects. In this study, according to the habits of human thinking and recognition, discrete expressions (such as discrete curved surface (DCS), and discrete body (DB)) were integrated and two novel representation types (including function structure and mapping structure) were put forward. A flexible and extensible ubiquitous knowledgeable data representation model (UKRM) was then constructed, in which structurally heterogeneous multiple expressions (including boundary representation (B-rep), constructive solid geometry (CSG), functional/parameter representation, etc.) were normalized. GIS’s ability in representing the massive, complicated and diversified 3D world was thus greatly enhanced. In addition, data reuse was realized, and the bridge linking static GIS to dynamic GIS was built up. Primary experimental results illustrated that UKRM was overwhelmingly superior to the current data models (e. g. IFC, CityGML) in describing both regular and irregular spatial objects
Rumen methane output and fermentation characteristics of gramineous forage and leguminous forage at differing harvest dates determined using an in vitro gas production technique
No full textAn in vitro rumen gas production technique was employed to determine the methane production and fermentation characteristics of Leymus chinensis and Medicago ruthenica at differing harvest dates (May 15, May 30, June 30, July 30, August 30 and September 30), which are sequential phases within a single continuous growth of two 10-year-old pastures. To quantify the rate of degradation and compare in vitro rumen fermentation characteristic, a logistic-exponential model, where initial gas volume was zero (LE0), was used to fit gas production and methane output results. Dried, milled forage samples were incubated in vitro for 72 h at 39°C and gas production was recorded intermittently throughout the incubation and gas samples were collected to measure methane production. Results showed that there were significant interactions between species and harvest for all chemical composition variables (P<0.001) and condensed tannin content (P<0.001). L. chinensis produced more total gas and methane than M. ruthenica (P<0.001). Both total gas and methane production decreased lineally (P<0.001) with advancing harvest date. The degradation rates of L. chinensis and M. ruthenica harvested on September 30 were lower than those on the other harvest dates (P<0.01). M. ruthenica fermented fluid had higher concentration of ammonia N (P<0.05) and molar proportions of isobutyrate (P<0.01), valerate (P<0.001) and isovalerate (P<0.01) in total volatile fatty acids than L. chinensis. Furthermore, concentration of isovalerate decreased cubically with advancing harvest date (P<0.05). In conclusion, M. ruthenica produced less methane than L. chinensis and the total gas and methane production decreased with advancing harvest date for both species, which may be due to the changes in contents of chemical compositions and condensed tannin in forages
无植物水平折流式潜流人工湿地对氮和磷的净化效果
No full text以炉渣、木块、砾石和木块、炉渣、砾石两组基质配置方式,构建无植物水平折流式潜流人工湿地,在不同水力停留时间(2 d、3 d和5 d)条件下,比较两组湿地系统(HB1和HB2)对模拟生活污水中氮、磷污染物的去除效果,同时分析优化的基质配置方式和水力停留时间。结果表明,当水力停留时间为3 d时,人工湿地系统的总氮去除率为71%~77%,当水力停留时间增加到5 d时,其去除率为79%~80%,提高不明显;当水力停留时间为3d时,其总磷去除率达到最高值50%,继续增加水力停留时间,其去除率反而下降。因此,无植物水平折流式潜流人工湿地的最佳水力停留时间为3 d。在进水端的前1/3基质区,HB1炉渣区和HB2木块区的氨氮质量浓度分别为13~17 mg/L和18~19 mg/L,硝态氮质量浓度为5.9~9.1 mg/L和0.4~2.8 mg/L。可见,炉渣能提高氨氮的去除率,木块有利于硝态氮的去除。HB1对氮污染物(尤其是氨氮)去除效果好于HB2,其基质配置方式为炉渣、木块和砾石;对磷的去除效果两种基质组合方式差别不大,木块、炉渣和砾石组合效果略好
基于面向对象分类方法的乌苏里江流域中俄跨境区域湿地景观动态研究
No full text选取乌苏里江中下游干流50 km缓冲区为研究区,以1989、2000和2013年的Landsat TM、OLI遥感影像为数据源,利用面向对象的分类方法获取湿地信息;在GIS技术支持下,选取斑块类别面积(CA)、面积所占比例(PLAND)、最大斑块面积指数(LPI)、平均斑块面积(AREA-MN)、斑块数(NP)、斑块密度(PD)等景观格局指数,分析了研究区1989~2013年湿地的景观格局动态特征。结果表明:面向对象的分类方法能够准确提取湿地信息,并且有效地避免“椒盐现象”;1989~2013年,该区水田、水库/坑塘、运河/水渠、灌丛沼泽增加和河流、湖泊、草本沼泽、森林沼泽减少;大量草本沼泽转为水田为该区湿地变化主要特征;1989年湿地类型以草本沼泽为主,2013年水田的斑块面积略高于草本沼泽斑块面积;湿地景观变化区主要分布于中国一侧的挠力河流域和穆棱河流域;天然湿地景观破碎化程度逐年加深,人工湿地景观趋于聚集,人为干扰是导致湿地景观格局变化的主要动力;中俄两国境内湿地景观变化程度差异显著,中国境内大量天然湿地转为人工湿地;俄罗斯境内的湿地变化微小,天然湿地保存较好。农田垦殖是导致两国湿地景观破碎程度差异的主要原因
可持续性科学研究热点及其知识基础——以Sustainability Science载文数据为例
No full text以Sustainability Science 2006—2015年间刊载的论文为基础数据,应用CiteSpace软件,采取文献共被引分析、关键词共现分析、突现词分析等方法对可持续性科学研究现状进行可视化分析。研究发现,Sustainability Science载文质量和国际影响力逐年上升;日、美、德、澳、加5国及东京大学、联合国大学、亚利桑那州立大学、茨城大学、京都大学、大阪大学、中国科学院等研究机构发文量位居前列,具有较强的研究实力。Komiyama H、Lang D J、Miller T R、Talwar S、Clark W S等是期刊载文引用较多的作者,显示了这些学者在可持续性科学领域的权威性。可持续性科学研究主要聚焦“可持续性”、“气候变化”、“概念框架”、“管治”、“脆弱性”、“适应性”、“恢复力”等热点问题。可持续性科学研究的知识基础主要包括“学科发展”、“跨学科研究”、“规划机制”、“灾害管控”、“信息管理”、“海岛环境”、“沿海脆弱性评估”、“土地利用”和“生态景观”等研究领域
松嫩平原盐碱地大规模开发的前期研究、灌区格局与风险控制
No full text半个多世纪的研究查明,松嫩平原苏打盐渍土是环境要素综合作用的结果,而蒸发使地表水析盐和地下水上升地表积盐的耦合机制是主导成因。盐类以苏打为主,类型包括盐土、碱土及衍生的盐-碱化土。面积393.70万hm~2,盐渍化过程还在持续。种稻排盐是改良苏打盐渍土的主要途径。古河道发现和试验示范为其大规模开发提供了可行性。大安等多个灌区建设具有强化粮食基地,优化环境和发展经济的综合效益,并成为东北地区第四大水稻区,使区域盐碱地开发形成完整格局。但是,这种盐碱地大规模开发存在使松花江和嫩江以及查干湖水体污染和土壤次生盐渍化的风险。在分析这些风险成因基础上,提出不向河湖直接排放稻田含盐碱尾水,并在查干湖外围建设湿地水处理系统的控制措施,防止对查干湖构成污染,采取将水田布置在古河道带等措施,控制旱田次生盐渍化