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991.
Although the adverse impacts of ocean acidification (OA) on marine calcifiers have been investigated extensively, the anti-stress capabilities regulated by increased light availability are unclear. Herein, the interactive effects of three light levels (30 μmol photons/(m2·s), 150 μmol photons/(m2·s), and 240 μmol photons/(m2·s) combined with two pCO2 concentrations (400 ppmv and 1400 ppmv) on the physiological acclimation of the calcifying macroalga Halimeda opuntia were investigated using a pCO2-light coupling experiment. The OA negatively influenced algal growth, calcification, photosynthesis, and other physiological performances in H. opuntia. The relative growth rate under elevated pCO2 conditions significantly declined by 13.14%?41.29%, whereas net calcification rates decreased by nearly three-fold under OA conditions. Notably, increased light availability enhanced stress resistance through the accumulation of soluble organic molecules, especially soluble carbohydrate, soluble protein, and free amino acids, and in combination with metabolic enzyme-driven activities, OA stress was alleviated. The carotenoid content under low light conditions increased markedly, and the rapid light curve of the relative electron transport rate was enhanced significantly by increasing light intensities, indicating that this new organization of the photosynthetic machinery in H. opuntia accommodated light variations and elevated pCO2 conditions. Thus, the enhanced metabolic performance of the calcifying macroalga H. opuntia mitigated OA-related stress. 相似文献
992.
The main purpose of this study was to examine the hydrogeochemical factors leading to nitrate contamination of shallow groundwater in an agricultural area. Another purpose was to identify relationships between variations in organic matter levels (as estimated by the BOD and COD parameters) of groundwater that transports effluent from small‐scale livestock holdings. Major cations, anions, BOD and COD of organic matter and total coliforms were analysed. It was found that groundwaters beneath cultivated areas and areas carrying livestock had higher concentrations of calcium, nitrate and chloride than did freshwater. Above all, the nitrification process increased concentrations of nitrate. Nitrate levels were depressed in some places where the groundwater was low in dissolved oxygen. Groundwaters affected by livestock activities showed high concentrations of organic matter (BOD, COD) and high microbial concentrations (as indicated by total coliforms). The COD/BOD ratio increased in the downward direction. It was inferred that this was due to the faster loss of easily biodegradable organic matter compared with non‐biodegradable organic matter proceeding away from a discharge. Accordingly, it is possible to trace effluent in a small area back to a point source by monitoring the COD/BOD ratio of groundwater. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
993.
根据《江苏统计年鉴(2002—2012)》的统计数据,运用熵值法和层次分析法相结合的主客观联合赋权法,对"十五"、"十一五"江苏省农业现代化水平进行评价.结果表明:江苏省农业现代化发展状态良好,研究时段农业现代化水平指数稳步上升,且上升势头强劲,2011年已进入完全成熟阶段,但是可持续发展状况起伏较大,尚不够稳定. 相似文献
994.
黄河流域农业水资源利用效率综合评估研究 总被引:2,自引:0,他引:2
为了评估黄河流域及其各省(区)农业水资源利用效率,根据专家意见与实际数据支撑构建农业水资源评估指标体系,采用熵权模型计算评估指标集中各指标的权重值,将各省(区)的评估指标通过权重加权,得到综合指数,对黄河流域及其各省(区)的综合农业水资源利用效率进行对比分析。结果表明,评估指标体系各指标的熵权计算值中,各指标的权重相差不大,表明评估指标集中各指标对综合指数的影响程度相当。黄河流域9省(区)的综合指数计算结果中,山西、山东、河南与陕西的综合农业水资源利用效率较高,甘肃、四川与内蒙古处于中等水平,而宁夏相较于其他几个省(区)明显低下。农业水资源利用效率低下的原因,与黄河调水量、农业基础设施情况及灌溉管理机制有关。黄河调水量的减少,使得国家分配给农业的调水量在不断减少;农业基础设施薄弱,直接导致农业用水浪费,灌溉水量增多;灌溉管理机制不完善,使得农业用水不合理,农业水资源利用效率不高。 相似文献
995.
Effect of salinity on the growth, biological activity and secondary metabolites of some marine fungi
HUANG Jingjing LU Chunhu QIAN Xiaoming HUANG Yaojian ZHENG Zhonghui SHEN Yuemao 《海洋学报(英文版)》2011,30(3):118-123
The study investigated the effects of salinity on growth,antimicrobial activities and secondary metabolites of 47 marine filamentous fungi isolated from the East China Sea near the western shore of the Taiwan Straits.The results indicate that NaCl promoted the growth up to 91.5% of test strains.However,only 14.9% of them showed a significant increase of antimicrobial activity against Candida albicans.When incubated in different concentrations of NaCl,the colony growth, antimicrobial activities and composition of secondary metabolites of the strain Ty01b-8 of Penicillium sp.varied.Treatment with KCl also showed a similar effect.An alkaloid isolated from the fermentation broth of Ty01b-8 was identified as chrysogine,inhibition activity of which against Hela cells was 15.05% at 20 μ g/ml,and yield was 4.4 and 4.9 times higher in 3 percent and 6 percent NaCl treatments,respectively, compared with the non-salt culture condition. These findings prove that salinity is an important factor influencing growth and secondary metabolites of some marine fungi,which can be used to screen for new metabolites from marine fungi,and to enhance their metabolites production in industrial fermentation. 相似文献
996.
Cultural Landscape Evolution of Traditional Agricultural Villages in North China —— Case of Qianzhai Village in Shandong Province 总被引:1,自引:0,他引:1
FANG Yangang LIU Jisheng 《中国地理科学(英文版)》2008,18(4):308-315
Agricultural village is an important rural type in China. The evolution process and mechanism of its cultural landscape are different from those of the industrialized village. The paper focuses this theme by a case study of Qianzhai Village of Qufu City, Shangdong Province. In the case of Qianzhai Village, the evolution of its settlement has experienced three stages: mechanical expansion, sprawling expansion and hollowing, and recentralization. The land- scape evolution of residents' houses has undergone three phases: traditional quadrangle house, one-storied house and multistoried house. The evolution of its land use has experienced three stages: circled stratification, fragment and intensive use, and concentration and extensive use. We can see that the main driving factors of cultural landscape evolution of agricultural village are the changes of rural population, society, economy and culture, which are influenced by the change of urban-rural relation, the national modernization process and economic development, the reform of family planning and land system, and the changes in governmental policies. In the future, the modernization, ecological trend, and individualization for residents' houses of agricultural villages in China will develop step by step. The recentralization of settlement and the scaled, sustainable, intensive land use are likely to be the trends of agricultural villages in China. 相似文献
997.
998.
GAOJun-feng LIChang-feng ZHANGHong-hui 《中国地理科学(英文版)》2003,13(1):25-29
This paper discusses the methods and process of Geographic Information System(GIS) applied in soil spatial analysis ,involving the collection of soil spatial data that GIS required ,spatial analysis method of soil nutrient,land use,slope and exposure of geography,crop yield and other factors,and also including acquiring soil spatial information and creating thematic map,and so on .Taking Hengjing Town in Wuxian County of Jiangsu Province as a case study and the maximum income as a principle,and applying the GIS methods and their interrelated models,we have calculated the most optimized agricultural land and the possible maximum income of Hengjing Town.According to the method,we can rationally regulate local agricultural production,and put forward some scenarios for optimizing agricultural structure of Hengjing Town .The paper puts forward an evaluation method of land adaptability based on soil spatial analysis,and offers some research clews to optimize agricultural land use constitutions.so the paper will be have important reference value for soil study. 相似文献
999.
现代农业发展所引发传统农业的多元化转变,在丰富农产品供应数量与质量、提高人民生活水平的同时,也造成国民经济行业的类型增加、结构调整等变化。这一变化也进一步改变了“大农业”模式下的农用地类型划分的合理性及其与国民经济行业、用地性质等之间的关系界定问题。本文通过梳理农业产业范围的变化情况及其对农用地的影响、土壤耕作层对农业地类划分的依据性、传统农用地与当前国民经济行业分类之间差异等问题,探索了造成农用地地类界定不断变化的历史因素和产业环境。结合这些研究结果,本研究有针对性地提出了意见建议,以期农业用地划分更加合理化。 相似文献
1000.
文本蕴含大量地理位置描述信息,有效融合地理关联信息以实现文本的精细定位是地理信息服务的难点。本文提出一种融合土地利用/覆被信息的描述地理位置的细粒度定位方法:在文本描述地理关联信息(地理位置实体、土地利用/覆被实体与空间关系)抽取、土地利用/覆被精细分类与地理位置粗粒度匹配定位的基础上,使用自然语言空间关系近似转换模型,确定地理位置的细粒度定位范围;基于土地利用/覆被实体及其周边精细分类信息,在该范围内检索匹配,确定地理位置的细粒度定位坐标。本文以野生亚洲象活动/肇事监测文本为例开展实验,并用匹配率与位置精度评价定位质量,结果表明:本文方法显著提升了地理位置的细粒度定位质量,实验精确匹配率(81.51%)、位置误差距离的均值(65.97 m)及其≤50 m的比例(70.50%)均优于国内主流在线地理编码与地名检索服务结合空间关系或其单独使用结果。该方法有助于完善地理位置定位方法体系、提升地理信息空间化质量,并可服务于野生动物活动/肇事监测预警等精细定位任务。 相似文献