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61.
62.
Zhenming Zhou Canyang Lin Shuwen Li Shupo Liu Fei Li Baoling Yuan 《Frontiers of Environmental Science & Engineering》2022,16(3):29
63.
缺磷是限制农林业产量的一个重要因子,传统的农林业生产主要通过施肥和土壤改良来满足植物对磷的需求,近年来人们开始发掘磷高效利用植物来替代传统方法提高磷的利用效率.A-65/27、A-65/31及A-61/186是目前世界上仅有的3个常绿杨树无性系,共同特点是容易扦插繁殖,造林成活率高,生长快,材质好.3个无性系的推广将极大地丰富南方用材林树种资源.为揭示磷素胁迫条件下常绿杨无性系对土壤中磷素的利用特性,通过沙培试验,设计5个磷素处理水平(磷的质量浓度依次是0.00、0.0310、0.0619、0.1239、0.1858 g·L~(-1)),进行不同磷素处理水平下常绿杨生长及生理生态特性的研究.结果表明:当磷的质量浓度为0.0619 g·L~(-1)时已经能满足常绿杨生长对磷的基本需求;磷素不足会明显的影响到常绿杨的生长.低磷胁迫下常绿杨高度、地径及生物量明显降低;低磷胁迫下光合速率也明显下降,通过对气孔导度及胞间二氧化碳浓度的变化趋势分析,导致光合速率下降的主要原因是非气孔限制因素,同步叶绿素荧光的测定表明光系统Ⅱ受到了一定的影响,这是非气孔限制因素之一. 相似文献
64.
65.
Forrest E. Dierberg 《Environmental management》1992,16(3):371-380
Following a period of prolonged drought or intentional lake level drawdown, large littoral areas that once contained submersed
aquatic vegetation (SAV) are reinundated when lake levels rise. A complete assessment of the contribution made by decomposing
SAV to the in-lake phosphorus (P) concentration is important in both the management of Lake Okeechobee and understanding basic
P processes. The P contribution to the open waters of Lake Okeechobee from a rapid inundation of exposed SAV was calculated
by four methods: cores of field-desiccated SAV, cores of lab-desiccated SAV in the presence and absence of sediments, in situ
decomposition, and sequential macrophyte harvesting. P releases, given such an episodic event, were similar among the four
methods, ranging from 116±48 to 384±528 mg/m2 in the absence of sediment. When SAV is in contact with sediment, which is the realistic field situation, the amount of P
released was four times less (30±14 mg/m2) than in the absence of sediment. The calculated P releases would result in total P concentration increases in the lake from
2 to 15 μg/liter (upper 95% CI=2–25 μg/liter) in the absence of sediment; only 1 μg/liter increase was predicted when SAV
released P in contact with sediment. Thus it is unlikely that a significant rise in total P concentrations in the limnetic
zone of the lake would occur from the export of P released during the desiccation of SAV in the littoral-marsh zone during
a drawdown. 相似文献
66.
城市污水除磷中的有关问题 总被引:10,自引:0,他引:10
分析了溶解氧浓度、污水中可生物降解有机物浓度及NOX浓度、污泥龄、污泥处理方式等对污水生物除磷的影响,在此基础上提出了提高污水除磷效果的工程措施,最后通过工程实例说明城市污水的除磷特点。 相似文献
67.
Assessment of labile phosphorus fractions and adsorption characteristics in relation to soil properties of West African savanna soils 总被引:2,自引:0,他引:2
O. C. Nwoke B. Vanlauwe J. Diels N. Sanginga O. Osonubi R. Merckx 《Agriculture, ecosystems & environment》2003,100(2-3):285
A large proportion of total P in the soils of the area is unavailable to plants and consequently P is the second most limiting nutrient. The labile and moderately labile phosphorus fractions and adsorption characteristics of surface and subsurface horizons of eleven soil profiles in the derived savanna (DS) and the northern Guinea savanna (NGS) of West Africa were assessed. The labile P fractions are the resin and HCO3-extractable inorganic (Pi) and organic (Po) P. The moderately labile fractions are the NaOH-extractable portion of soil P in the Hedley sequential procedure. In the DS soils, the resin P, considered the most readily available fraction, varied from 1 to 14 mg kg−1, HCO3-Pi ranged from 3.3 to 11, and HCO3-PO was between 4 and 12 mg kg−1 in the surface horizon. In the NGS, the topsoil contained 1.5–3 mg kg−1 of resin P, 5–8 mg kg−1 of HCO3-Pi, and 7.5–9.7 mg kg−1 of HCO3-Po. Sodium hydroxide-Po was the largest of the fractions in all the soils studied. It ranged from 23 to 55 mg kg−1 in the topsoil. In general, the labile P levels were higher in soils of the DS than of the NGS and were related to the oxalate-extractable Fe (Feox), and Al (Alox) as well as to soil texture. The subsoil of Kasuwan Magani (profile KS 9–21 cm) required 153 mg P kg−1 to maintain 0.2 mg P l−1 in solution (standard P requirement), and Danayamaka (profile DD 7–32 cm) required 145 mg P kg−1. These could translate to 214 and 200 kg P ha−1 if a plow layer of 10 cm is assumed. Because these are within the plow layer, more P fertilizer would be needed for crop production than in the other soils. The standard P requirement and the adsorption maxima were related to Feox and Alox, dithionite-Fe (Fed), and texture. The increase in labile P content with decreasing Feox and Alox could imply that management practices capable of reducing the activities of Fe and Al in solution might improve P availability. 相似文献
68.
珠江广州市区河段磷的迁移和分布的初步研究 总被引:3,自引:0,他引:3
研究了珠江广州市区河段黄沙-员村全程13100m水域和底泥中不同形态磷的含量分布。并探讨磷在水体和底泥中的转移途径,为水污染的防治提供科学依据。 相似文献
69.
水培蔬菜法对富营养化水体中氮磷的去除特性研究 总被引:6,自引:1,他引:6
利用水培蔬菜法净化富营养化河水,考察了不同形态的氮磷在处理前后的变化,在此基础上阐明水培法去除富营养化水体中氮磷的过程与机理。 相似文献
70.
沉积物中磷负荷及其释放对水质的影响 总被引:6,自引:0,他引:6
以华东师范大学校河为研究对象,通过野调研与室内模拟实验相结合,研究了校河沉积物中磷负荷量,释放量与释放速度以及温度和水体扰动对其影响,并探讨了沉积物中磷释放对校河水质的影响,为校河的富营养化防治提供科学依据。 相似文献