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不同氮磷比对多年生水生植物生长特性影响的研究 总被引:1,自引:0,他引:1
从氮、磷等植物生长的环境因子出发,研究了高低氮磷营养水平下,不同氮/磷比例的富营养化水体对聚草(Myriophyllum spicatum)、黄花水龙(Jussiaea stipulacea Ohwi)、喜旱莲子草(Alternanthera philoxeroides)生长特性的影响。结果表明,聚草在氮磷比2:1时生物量最大,且生物量在高浓度水平处理明显大于低浓度水平处理(P〈0.01);黄花水龙在氮磷比10:1~20:1时生物量最大,高低浓度水平处理问生物量无显著性差异;喜旱莲子草在较高氮磷比20:l~40:1时生物量最大,高浓度水平处理时生物量显著性高于低浓度水平处理(P〈0.05)。在低浓度水平处理时,氮为黄花水龙和喜旱莲子草生长的主要限制因子,磷为聚草生长的主要限制因子,且喜早莲子草叶绿素增长期较其他处理提前,而黄花水龙的叶绿素变化在高低营养水平下差异不显著。营养盐水平对聚草茎长和生物量的影响较对黄花水龙和喜旱莲子草的影响明显。 相似文献
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Internally mixed sea salt, soot, and sulfates at Macao, a coastal city in South China 总被引:1,自引:0,他引:1
Li W Shao L Shen R Yang S Wang Z Tang U 《Journal of the Air & Waste Management Association (1995)》2011,61(11):1166-1173
Direct observation of the mixing state of aerosol particles in a coastal urban city is critical to understand atmospheric processing and hygroscopic growth in humid air. Morphology, composition, and mixing state of individual aerosol particles from Macao, located south of the Pearl River Delta (PRD) and 100 km west of Hong Kong, were investigated using scanning electron microscopy (SEM) and transmission electron microscopy coupled with energy-dispersive X-ray spectrometry (TEM/EDX). SEM images show that soot and roughly spherical particles are prevalent in the samples. Based on the compositions of individual aerosol particles, aerosol particles with roughly spherical shape are classified into coarse Na-rich and fine S-rich particles. TEM/EDX indicates that each Na-rich particle consists of a Na-S core and NaNO3 shell. Even in the absence of heavy pollution, the marine sea salt particles were completely depleted in chloride, and Na-related sulfates and nitrates were enriched in Macao air. The reason could be that SO2 from the polluted PRD and ships in the South China Sea and NO2 from vehicles in the city sped up the chlorine depletion in sea salt through heterogeneous reactions. Fresh soot particles from vehicular emissions mainly occur near curbside. However, there are many aged soot particles in the sampling site surrounded by main roads 200 to 400 m away, suggesting that the fresh soot likely underwent a quick aging. Overall, secondary nitrates and sulfates internally mixed with soot and sea salt particles can totally change their surface hygroscopicity in coastal cities. 相似文献
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Li-Fang Hu Hua-Jun FengYu-Yang Long Yuan-Ge ZhengCheng-Ran Fang Dong-Sheng Shen 《Waste management (New York, N.Y.)》2011,31(1):124-130
The liquid-to-solid ratio (L/S) of semi-solid Fenton process (SSFP) designated for hazardous solid waste detoxication was investigated. The removal and minimization effects of o-nitroaniline (ONA) in simulate solid waste residue (SSWR) from organic arsenic industry was evaluated by total organic carbon (TOC) and ONA removal efficiency, respectively. Initially, Box-Behnken design (BBD) and response surface methodology (RSM) were used to optimize the key factors of SSFP. Results showed that the removal rates of TOC and ONA decreased as L/S increased. Subsequently, four target initial ONA concentrations including 100 mg kg−1, 1 g kg−1, 10 g kg−1, and 100 g kg−1 on a dry basis were evaluated for the effect of L/S. A significant cubic empirical model between the initial ONA concentration and L/S was successfully developed to predict the optimal L/S for given initial ONA concentration for SSFP. Moreover, an optimized operation strategy of multi-SSFP for different cases was determined based on the residual target pollutant concentration and the corresponding environmental conditions. It showed that the total L/S of multi-SSFP in all tested scenarios was no greater than 3.8, which is lower than the conventional slurry systems (L/S ? 5). The multi-SSFP is environment-friendly when it used for detoxication of hazardous solid waste contaminated by ONA and provides a potential method for the detoxication of hazardous solid waste contaminated by organics. 相似文献