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991.
有机无机肥配施对超级杂交稻产量构成及植株重金属含量的影响 总被引:3,自引:0,他引:3
以超级杂交稻"Y两优1号"为供试材料,保持总施氮量不变(180 kg.hm-2)条件下,研究不同比例有机无机肥配施对超级杂交稻产量构成及植株重金属含量的影响。结果表明,由施肥量-产量模型进行模拟,得到有机肥与尿素施入量分别为606.75和288.18 kg.hm-2时,水稻产量最高(10 084.37 kg.hm-2);有机肥和尿素施用量分别为202.32和353.17 kg.hm-2时,经济效益最佳(产量为9 968.42 kg.hm-2)。不同比例有机无机肥配施对植株镉含量无显著影响。在6个梯度处理中,有机肥和尿素施肥量分别为600和289.27 kg.hm-2处理产量最高,且植株铬含量最低。 相似文献
992.
2009年3月,采集天津城区PM10和PM2.5样品,分析其中的水溶性无机离子、有机碳(OC)和元素碳(EC),并估算其二次有机碳(SOC)浓度及消光系数.结果表明,天津城区PM10和PM2.5污染严重,水溶性无机离子和含碳物质在PM10中的比例为24.8%和10.0%,在PM2.5中的比例为26.6%和13.9%;SO42-、NO3-和Ca2+是主要的无机离子,霾日天气有利于SO2和NO2向硫酸盐和硝酸盐的二次转化;通过OC/EC最小比值法估算SOC的浓度,表明SOC与OC的比值分别为38%(PM10)和24%(PM2.5),霾日天气有利于SOC生成;二次离子(SO42-,NO3-和NH4+)、粗粒子、OC和EC是大气消光的主要贡献者,其消光贡献比例分别为33.1%, 22.6%,22.0%和15.6% 采用化学组分和相对湿度可以较好的拟合大气消光系数及大气能见度. 相似文献
993.
利用指数模型和幂函数模型对2007年和2010年长江中下游4个湖泊58个样本 ad(λ)(非色素颗粒物吸收系数) 光谱进行拟合,以 R2(决定系数)、RE(相对误差)和RMSE(均方根误差)等统计参数判定模型效果. 指数模型和幂函数模型 R2平均值、RE、RMSE分别为0.998、7.01%、0.015 m-1和0.994、15.90%、0.027 m-1. 统计检验显示,指数模型的 R2显著大于幂函数模型(ANOVA,P<0.001),而RE和RMSE则显著小于幂函数模型(ANOVA,P<0.001). 指数模型能更准确地拟合 ad(λ),得到的 Sd(光谱斜率)平均值为(12.21±1.08)μm-1,400~700 nm波段内变异系数为8.85%,空间上4个湖泊之间变化不是很明显,仅傀儡湖的 Sd略低于其他3个湖泊. ad(λ)与ρ(ISM)(无机悬浮颗粒物浓度)呈极显著正相关,通过ρ(ISM)可以得到长江中下游典型浅水湖泊 ad(λ)光谱模型. 相似文献
994.
16 年长期定位试验结果表明: 在湘南第四纪红壤中, 长期施用化肥下土壤对 H2 P O-4 的吸附量相对较大, 化肥+ 秸秆还田下则较小; 不同 H2 P O-4 吸附量范围内的解吸量和解吸率则均以化肥+ 秸秆还田较高。 相似文献
995.
996.
In 2004, airborne particulate matter (PM) was collected for several aerosol episodes occurring in the southern region of Taiwan.
The particulate samples were taken using both a MOUDI (Micro-orifice Uniform Deposit Impactor) and a nano-MOUDI sampler. These
particulate samples were analyzed for major water-soluble ionic species with an emphasis to characterize the mass concentrations
and distributions of these ions in the ambient ultrafine (PM0.1, diameter <0.1 μm) and nano mode (PMnano, diameter <0.056 μm) particles. Particles collected at the sampling site (the Da-Liao station) on the whole exhibited a typical
tri-modal size distribution on mass concentration. The mass concentration ratios of PMnano/PM2.5, PM0.1/PM2.5, and PM1/PM2.5 on average were 1.8, 2.9, and 71.0%, respectively. The peak mass concentration appeared in the submicron particle mode (0.1 μm < diameter <1.0 μm).
Mass fractions (percentages) of the three major water-soluble ions (nitrate, sulfate, and ammonium) as a group in PMnano, PM0.1, PM1, and PM2.5 were 18.4, 21.7, 50.0, and 50.7%, respectively. Overall, results from this study supported the notion that secondary aerosols
played a significant role in the formation of ambient submicron particulates (PM0.1−1). Particles smaller than 0.1 μm were essentially basic, whereas those greater than 2.5 μm were neutral or slightly acidic.
The neutralization ratio (NR) was close to unity for airborne particles with diameters ranging from 0.18 to 1 μm. The NRs
of these airborne particles were found strongly correlated with their sizes, at least for samples taken during the aerosol
episodes under study. Insofar as this study is exploratory in nature, as only a small number of particulate samples were used,
there appears to be a need for further research into the chemical composition, source contribution, and formation of the nano
and ultrafine mode airborne particulates. 相似文献
997.
998.
耐高温解无机磷菌解磷条件的优化 总被引:2,自引:1,他引:1
为提高堆肥中添加难溶性磷的转化效率,对筛选于高温堆肥中的耐高温解无机磷菌株(BL161)解磷条件进行优化研究. 利用正交设计表L25(56)选择培养时间,温度,pH,磷矿粉添加量和菌剂接种比例作为参考因素,对该菌株进行发酵培养. 结果表明:该菌株的最佳解无机磷条件是培养基pH为4.5,磷矿粉添加量与接种量分别为9.0 g/L和7%,于38 ℃下培养25 d,解磷总量(274 mg/L)达到最大;对温度指标分析显示,该菌株的温度耐受范围较广,在34~50 ℃下均能进行解无机磷活动,38 ℃为最适解无机磷培养温度;该菌株的耐热性较高,在50 ℃下能够很好地定植和解无机磷,发酵液中ρ(磷矿粉)随着培养时间的增加呈上升趋势,并于培养的第25天达到209 mg/L;极差分析显示,发酵时间对解磷总量的影响最大(R时间152.2),其他各因素对解磷总量的影响大小依次为pH>温度>磷矿粉添加量>接种量. 相似文献
999.
Securing adequate safe drinking water and proper sanitation is a major challenge facing the developing world. The “Water for
Life Decade” emphasizes the importance of upgrading national water quality and sanitation services. This study assessed the
domestic water profile in the city of Beirut. Samples were collected from three types of household water sources (municipality,
private wells, and vended water bottles) and assessed for their physiochemical and microbiological profile. At the same time,
a cross-sectional survey assessing water consumption patterns and the prevalence of water-borne diseases was conducted. The
results showed a deficient water quality profile in all three water sources. The measured physiochemical and bacteriological
parameters reflected the high frequency of water-borne diseases. Action to secure a safe domestic water supply is essential.
The plan should guarantee the protection of water sources, ensure sufficient treatment of domestic water and upgrade the national
program for potable water quality control. Periodic quality monitoring and legislating the chaotic water-vending sector are
indispensable. Additionally, the deterioration of private well sources by sea and wastewater infiltration necessitates the
enforcement of legislation associated with the use and management of private wells. Consumer awareness and active contributions
to promote and protect public health are important. 相似文献
1000.
Hooghly–Matla estuarine ecosystem of India is very rich in natural resources and receives large amount of nutrients through litterfall from adjacent mangrove forest. Nitrogen as an important nutrient occurs in various forms and plays a crucial role in the regulation of productivity in this estuarine system. Modelling of nitrogen dynamics from mangrove litterfall and particularly the release of dissolved inorganic nitrogen in this estuarine system is important because of its role in augmenting growth of phytoplankton and other higher plants and all other biological components of grazing food chain. 相似文献