沙湖水体污染现状及对策分析   总被引：1，自引：0，他引：1  

任学蓉  张宁惠 《干旱区资源与环境》2007,21(6):103-107

本文对沙湖水体营养盐来源进行了调查分析,结果表明:①黄河水、农田退水的补给是沙湖营养盐的主要来源;②2004年由黄河水补给入湖的总氮、总磷量分别为20.00t和3.04t,占全年入湖总氮、总磷量的50.4%和57.7%;③2004年由农田退水补给入湖的总氮、总磷量分别为15.00t和2.00t,占全年入湖总氮、总磷量的37.8%和37.9%;④2004年由芦苇收割和渔业捕捞出湖的总氮、总磷量分别为11.99t和1.93t,占全年入湖总氮、总磷量的30.2%和36.6%;在调查沙湖营养来源的基础上,建立沙湖水质经验模型并分别对模型进行验证,结果表明,OECD模型能较好预测沙湖水体总磷、总氮浓度。最后利用该模型,对所提出的沙湖水体富营养化防治方案进行计算分析比较,并确定合适的防治方案。  相似文献   

基于landsat卫星影像的水库水体总磷质量浓度反演研究     

王云霞  杨国范  林茂森  杨舒婷 《灌溉排水学报》2017,36(4)

以清河水库为研究区域,利用Landsat8卫星OLI数据及实地观测数据,建立了适于清河水库水体总磷质量浓度的最小二乘支持向量机(LS-SVM)遥感反演模型,并对清河水库总磷量进行了反演分析。结果表明,LS-SVM模型的平均相对误差为6.06%,相比于单波段线性回归反演模型及波段组合线性回归模型,平均误差分别降低了20.77%、12.53%,显著提高了清河水库水体总磷质量浓度反演的模型精度,达到遥感反演预测精度要求;利用LSSVM反演模型对清河水库总磷量反演显示,水体中总磷质量浓度主要集中在0.04~0.08 mg/L,水库水体总磷质量浓度总体偏高。  相似文献   

菝葜属植物化学成分研究进展   总被引：3，自引：0，他引：3  

刘俊彦  黄文华  傅建熙 《陕西林业科技》1999,(3):64-71

概述了近几十年来菝葜属植物化学成分研究的进展，着重介绍了在本属植物中所发现的甾体皂甙类化合物的分离技术、结构鉴定和结构特性。  相似文献   

Quecksilber und Methylquecksilber in Böden und Pflanzen unterschiedlich belasteter Standorte der Slowakei. Mercury and methylmercury in soils and plants of differently contaminated sites in Slovakia     

Renta Dombaiov  Jen‐How Huang  Egbert Matzner 《植物养料与土壤学杂志》2005,168(2):238-240

  相似文献   

Postharvest UV-C treatment combined with 1-methylcyclopropene (1-MCP), followed by storage in continuous low-level ethylene atmosphere,improves the quality of tomatoes     

Penta Pristijono  Konstantinos Papoutsis  Christopher J. Scarlett  Michael C. Bowyer  Quan V. Vuong  Costas E. Stathopoulos 《The Journal of Horticultural Science and Biotechnology》2017,92(5):521-529

Mature green tomatoes (Solanum lycopersicum L. cv Neang Pich) were exposed to 13.6 kJ m^?2 UV-C or 0.5 μL L^?1 1-MCP or combination of 13.6 kJ m^?2 UV-C and 0.5 μL L^?1 1-MCP, with appropriate untreated controls. After treatment, tomatoes were stored in air containing 0.1 μL L^?1 ethylene at 20°C and 100% RH. The untreated fruit ripened significantly faster than those of all other treatments. UV-C treatment alone was able to delay fruit ripening by up to 5 days longer compared to untreated fruits whilst the additional of 1-MCP further delayed fruit ripening. UV-C and 1-MCP treatments alone or in combination had significantly slower ethylene production rates throughout the storage period. The fruit treated with the combination of 1-MCP and UV-C was significantly firmer and had higher total phenolic content compared to that of the other treatments. However, there was no difference between treatments in soluble solids content/titratable acids ratio, chlorophyll content, lycopene content and total antioxidant activity. These results show that UV-C and 1-MCP treatment delay ripening and improve the quality of tomatoes in the presence of low-level ethylene during storage. This new treatment could be used to extend the shelf-life of mature green tomatoes through the supply chain without the use of refrigeration.  相似文献   

响应面法优化米口袋总黄酮的超声提取工艺     

史美荣 《中国农学通报》2017,33(23):129-137

旨在采用超声波辅助法提取米口袋中总黄酮并对工艺进行优化。在单因素实验的基础上,确定料液比、超声温度、超声功率、超声时间4个因素的Box-benhnken的实验设计。以总黄酮的提取率为响应值,采用响应面法优化米口袋总黄酮的提取工艺,建立并分析各因素与指标值的数学模型。最佳工艺参数为:料液比1:40 g/m L,超声温度45℃,超声功率300 W,超声时间60 min,总黄酮提取率理论值为8.08%,实际值为8.22%,相对标准偏差为0.33%。本实验方法具有操作简便、提取时间短和成本低等优点,可为后期米口袋的研究提供理论依据。  相似文献   

无柄小叶榕等4种容器苗质量评价中关键生理因子筛选的初步研究     

陈秋夏郑坚  张庆良林霞 《浙江亚热带作物通讯》2007,29(1):1-11

本研究通过栽培无柄小叶榕等4种乔木在15种轻基质中不同组合的苗圃期和出圃实验，建立容器苗质量评价及预测线性回归模型，探讨了苗圃期植株生理指标在解释苗圃期生长表现（干重总生物量、干重根茎比）和预测出圃生长表现中（存活率、株高、地径、相对生长速率）的作用，推荐叶片总叶绿素含量为容器苗质量评价体系中的最关键生理因子。  相似文献   

Methyl Jasmonate Counteract UV-B Stress in Barley Seedlings     

I. Fedina  D. Nedeva  K. Georgieva  & M. Velitchkova 《Journal of Agronomy and Crop Science》2009,195(3):204-212

The role of exogenously applied phytohormone methyl jasmonate (MeJA) in counteracting the ultraviolet B (UV‐B) stress in barley seedlings was investigated. Barley seedlings (Hordeum vulgare L., cv. Alfa) 4 days old were supplied with 5 × 10^?5 m MeJA through the roots for 3 days and then exposed for 2 days for 5 h per day to UV‐B (312 nm, biological effectiveness of UV‐B radiation 28.8 kJ m^?2day^?1). The rate of ¹⁴CO₂ fixation, PSI and PSII activities and chlorophyll content decreased, but flavonoids, H₂O₂, malondialdehyde, proline and UV‐B induced compounds increased after UV‐B treatment. The rate of photosynthetic oxygen evolution was more strongly inhibited by UV‐B‐irradiation than PSI and PSII efficiency. MeJA itself increased the content of free proline, which acts as a stress protector due to its radical scavenging ability. Increased superoxide dismutase, catalase and peroxidase (POX) activities in the leaves and in the roots and the POX isoforms induction revealed the MeJA involvement in plant tolerance to oxidative stress caused by UV‐B irradiation. It was shown that pre‐treatment with MeJA counteracted UV‐B stress. Therefore, it was suggested that MeJA could acts as a mediator in plant defense responses to UV‐B irradiation by enhancing the activity of antioxidant system and free radical scavenging capability of plant cells.  相似文献   

Nitrate leaching in a silage maize field under different irrigation and nitrogen fertilizer rates   总被引：4，自引：0，他引：4  

Mahdi Gheysari  Seyed Majid Mirlatifi  Mehdi Homaee  Gerrit Hoogenboom 《Agricultural Water Management》2009,96(6):946-954

Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO₃) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO₃-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189 kg N ha⁻¹), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60 cm soil depths for all 36 experimental plots. Soil NO₃-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO₃-N leaching out of the 60-cm soil layer was 8.43 kg N ha⁻¹, for the 142 kg N ha⁻¹ and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO₃ concentration at the 60 cm depth was 46 and 138 mg l⁻¹, respectively. Based on our findings, it is possible to control NO₃ leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management.  相似文献   

Effects of formalin on total haemocytes count and histopathological changes in the shrimp Litopenaeus schmitti (Pérez‐Farfante & Kensley 1997)     

Raico E Laria Lamela  Yanis Cruz Quintana  Raquel Silveira Coffigny  Mercedes Martínez  Norma González Herrate 《Aquaculture Research》2008,39(12):1316-1321

Formalin is used in shrimp industry to eliminate ectoparasites and as a disinfectant. However, the effect of formalin on shrimp's defense mechanism is unknown. Several biomarkers were used to assess the immune response of juveniles of the shrimp Litopenaeus schmitti exposed to different concentrations of formalin (10, 25 and 50 mg L^?1) during 24 and 48 h. Formalin concentrations of 25 and 50 mg L^?1 produced a significant reduction in the total haemocyte count at both 24 and 48 h. Peroxidase and phenoloxidase activity did not show variations. The total protein concentration in haemolymph of shrimps was not significantly different between experimental groups. Histological analysis showed hyperplasia in the gills of animals exposed at 10 mg L^?1 for 24 h; however, the exposure at 25 and 50 mg L^?1 caused necrosis in gills, hepathopancreas and the antennal gland.  相似文献