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61.
Vesna Zupanc Martina ŠturmSonja Lojen Nina Marši?-KacjanJoseph Adu-Gyamfi Branka Bra?i?-?eleznikJanko Urbanc Marina Pintar 《Agriculture, ecosystems & environment》2011,144(1):167-174
In the search for new technologies that would ensure optimum yield and environmental sustainability, various irrigation, nitrogen and cropping system management strategies for the production of vegetables with a shorter growing period were assessed at a benchmark site in Slovenia for the years 2006 and 2007. In the studied years four irrigation and fertilization treatments were applied: (1) 50% drip irrigation of plants water requirements ETcrop and the farmer's practice of fertilisation (broadcasting), (2) fertilisation and 100% drip irrigation (fertigation), (3) the farmer's practice of irrigation (sprinkler irrigation using water stored in plastic tanks) and fertilisation, and (4) control (the farmer's practice of irrigation but no fertilisation). An equivalent of 80, 80 and 200 kg ha−1 of nitrogen (N), 50, 50 and 80 kg ha−1 of phosphorous (P) and 120, 120 and 300 kg ha−1 of potassium (K) was added for iceberg lettuce, endive and cabbage, respectively. Nitrogen (N) labelled fertilizer (15N) was applied to trace the movement of the applied N fertiliser. The tested irrigation and fertilisation techniques for the production of vegetables with a shorter growing period in the Slovenian climate showed that environmentally sustainable practices (split application of nutrients compared to broadcast incorporating fertilisation) should be a practice of choice in water protection zones. The results confirm that fertigation and improved irrigation scheduling can be an effective way of minimizing nitrate leaching, and should be considered for vegetable production in or close to groundwater protection zones. 相似文献
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63.
选取辽河盘锦段至河口近岸海域区域进行研究水体中氨氮、硝酸盐氮和亚硝酸盐氮的分布特征及其与溶解氧的关系进行研究。结果表明水中氮素含量高于海水,且氨氮表现尤为突出,可能与水体中溶解氧含量和微生物环境、海水的稀释和迁移有很大关系;河水中氮素与溶解氧的呈显著负相关,而海水中氮素与溶解氧的关系不明显。这可能与海水的质化作用有关。 相似文献
64.
通过对环境样品保存过程中NH3-N、NO2-N、NO3-N及总氮的测定来研究水样中氮转化规律,找出三氯在一定条件下相互转化规律关系,提高环境样品中三个分析项目的分析准确性,正确反应环境样品中的真实情况。对于认识水体中氮的循环,防止水体污染,保护水域环境,充分利用开发水资源有着十分重要的意义。 相似文献
65.
采用ICS-1500离子色谱仪与淋洗液自动发生器联用,等浓度淋洗,用AS40自动进样,同时测定地下水中氟化物、氯化物、硫酸盐和硝酸盐氮。该方法简便快捷,灵敏度高,极大提高了分析的效率,适用于地下水中四项阴离子的检测。 相似文献
66.
Yuan Cheng Qinqin Yu Jiumeng Liu Youwen Sun Linlin Liang Zhenyu Du Guannan Geng Wanli Ma Hong Qi Qiang Zhang Kebin He 《Frontiers of Environmental Science & Engineering》2022,16(2):18
67.
Ling Sun Hui Wang Yuanqing Kan Shiliang Wang 《Frontiers of Environmental Science & Engineering》2018,12(6):13
To reveal the distribution characteristics of phytoplankton and the main influence factors under different conditions in the urban rivers, the investigations were conducted during autumn and winter 2014 in Changzhou City, East China. 178 taxa of phytoplankton belonging to 28 functional assemblages were identified. In autumn, the phytoplankton community compositions have high similarity for enhanced hydrological connectivity. The chlorophytes and diatoms (prevailing functional groups C, F, J, P), together with euglenoids (W1), showed high proportions of biomass in the main rivers and connected rivers. It was related to the well mixed eutrophic conditions. The phytoplankton community exhibited spatiotemporal heterogeneity in winter. Affected by the low water level and temperature, the free-living phytoflagellates (X2) replaced groups F and J in the main rivers. Phytoplankton productivity was the highest in the Tongji River. Chlorophytes Dictyosphaerium ehrenbergianum and Chlamydobotrys stellata had an overwhelming superiority during the winter bloom. They were significantly correlated with ammonium, total phosphorus and biochemical oxygen demand. Affected by tail water supply, the diatoms (MP) and euglenoids (W1) dominated in a beheaded river. The multivariate analyses based on the phytoplankton functional groups helped to evaluate the relationships and variations between the urban rivers. The redundancy analysis (RDA) results showed that nitrate nitrogen, water temperature, total nitrogen and total suspended solids were the main influence factors on the phytoplankton community. Except MP, the prevailing groups all showed significant negative correlations with nitrate nitrogen. Availability and utilization of dissolved inorganic nitrogen and hydrodynamic conditions affected the phytoplankton distribution.
相似文献
68.
用AQUA800辨别分析仪同时测定地面水中的氨、硝酸盐、亚硝酸盐、氯化物、正磷酸盐、总硬度和硅酸盐,是一种简便、迅速、准确、可靠的测定方法,样品无需预处理,精密度试验其变异系数分别为1.24%、2.18%、2.02%、2.67%、2.35%、3.57%、4.78%,加标回收率分别为103.5%、101.0%、95.0%、99.2%、97.6%、101.5%、98.0%,方法检测限分别为氨0.022mg/L,硝酸盐0.015mp/L,亚硝酸盐0.002tug/L,氯化物0.47mg/L,正磷酸盐0.015mg/L,总硬度17.6mg/L,硅酸盐0.55mg/L,能满足地面水中辨别分析仪同时测定氨、硝酸盐、亚硝酸盐点化物、正磷酸盐、总硬度和硅酸盐分析测定的要求。 相似文献
69.
利用差热分析仪分析和研究了敞开气氛中硝酸铵的热分解过程,通过在硝酸铵样品中加入酸性物质、KCl、有机物等各种杂质,研究硝酸铵热分解过程的影响因素。结果表明,在敞开气氛中,酸性物质和KCl对硝酸铵热分解过程具有催化作用,有机物会降低硝酸铵的热稳定性,研究结论可以为解决硝酸铵的生产、储存和运输过程中的安全问题提供重要参考。 相似文献
70.
The effects of nitrate additions on the physics, chemistry and biology of lake water were studied in 5 × 10 m polyethylene enclosures installed in Lake Kastoria, a shallow eutrophic lake in Northern Greece. The water physics, chemistry, chlorophyll a and nitrogenase activity were monitored from July 10 till October 17 1985 at 2 week intervals. The experiment included a control enclosure.
Water confinement in the control enclosure resulted in ammonia accumulation, a slight decrease in chlorophyll a, a significant reduction of nitrogenase activity and an increase in phosphorus release from the sediments at the end of the experimental period.
The addition of KNO3 resulted in higher than the control accumulation of NH3, chlorophyll reduction, increase in water transparency and reduction of nitrogenase activity. Large losses of nitrogen added were measured which were attributed to denitrification, organic matter sedimentation and ammonia volatilization. Anaerobic but not aerobic phosphorus release from sediments was inhibited at the end of the period. The reduction of nitrogenase activity and of chlorophyll a concentration are attributed to changes in phytoplankton composition from blue-greens to small-sized species grazed by zooplankters. 相似文献
Water confinement in the control enclosure resulted in ammonia accumulation, a slight decrease in chlorophyll a, a significant reduction of nitrogenase activity and an increase in phosphorus release from the sediments at the end of the experimental period.
The addition of KNO3 resulted in higher than the control accumulation of NH3, chlorophyll reduction, increase in water transparency and reduction of nitrogenase activity. Large losses of nitrogen added were measured which were attributed to denitrification, organic matter sedimentation and ammonia volatilization. Anaerobic but not aerobic phosphorus release from sediments was inhibited at the end of the period. The reduction of nitrogenase activity and of chlorophyll a concentration are attributed to changes in phytoplankton composition from blue-greens to small-sized species grazed by zooplankters. 相似文献