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981.
用渗透势不同的聚乙二醇(PEG)6000模拟外界环境水分条件,对高梁不同品种的种子在萌动、萌发及成苗3个阶段水分需求的量化研究表明:种子的抗旱性随吸水进程的推进而减弱,种子在萌动、萌发及出士成苗的时间(t)与外界环境水势(w)之间存在着1/t=a+bw的关系,据此推算不同品种在不同成苗阶段的需水阈值,发现不同品种在同一成苗过程中对环境水分条件的反应不同,抗旱性也不同. 相似文献
982.
The leaching concentrations of different metals in stainless steel pickling residue(SSPR)were determined and the toxic metals were treated using Na_2 S·xH_2 O,FeSO_4·6 H_2 O,and phosphoric acid.A modified European Community Bureau of Reference(BCR) sequential extraction was used to identify the speciation of the concerned metals.Results showed that SSPR contains a large amount of Ca(58.41%),Fe(29.44%),Cr(3.83%),Ni(2.94%),Mn(2.82%) and some of Al,Cu,Mg,Zn.Among them,Cr and Ni were the most toxic metals in SSPR,thus the raw SSPR falls into hazardous waste category due to the leaching amount of Cr.In addition,the leached Cr was identified as Cr6+(MgCr04) in the waste.BCR test revealed that risk assessment code(RAC) of Cr and Ni were 33.29% and 61.7%,indicating they posed "high" and "very high" risk to the environment,respectively.After fixing by Na_2 S·xH_2 O and FeSO_4·6 H_2 O,the leaching concentrations of Cr and Ni were less than 1.5 and 0.5 mg/L,respectively.After fixing by Na_2 S·xH_2 O and FeSO_4·6 H_2 O the tre ated SSPR can be safely reused as roadbed materials,concrete and cement aggregates.This study provides a useful implication in treatment and beneficial reuse of heavy metal-containing hazardous wastes. 相似文献
983.
Penghui Li Min Su Xiaodan Wang Xiaoyan Zou Xia Sun Junpeng Shi Hongwu Zhang 《环境科学学报(英文版)》2020,32(2):248-259
Silver nanoparticles (AgNPs) are widely used in many consumer products, whereas their environmental behaviors in natural aquatic systems remain unknown, especially in natural brackish media. Therefore, it is urgent to investigate the environmental fate of AgNPs in natural brackish waters. Here, we investigated the stability of citrate-coated AgNPs in natural brackish water collected from 6 different sites with distinct salinities in the Xinglinwan Reservoir, located in Xiamen City, southeast China. The obtained results showed that AgNP colloids remained stable in low-salinity waters, which was mainly determined by the effects of dissolved organic matter (DOM) promoting the stability of the nanoparticles. However, the environmental fate of AgNPs in high-salinity waters was dominated by the salinity or ionic strength, especially the free ion concentrations of Cl?, SO42?, or S2?, resulting in rapid sedimentation and dissolution. In addition, both DOM and salinity contributed to the environmental behavior of AgNPs in moderate-salinity waters, ultimately resulting in either colloidal stability or sedimentation. Overall, these results may reveal that AgNPs remain relatively stable for a long period in low-salinity natural waters, and that the stability might gradually decrease as AgNPs are transferred from freshwaters through brackish waters and eventually end up in seawater along the bay. Our findings also further indicate that the toxicity and potential risks of AgNPs may present more serious threats to the environment and organisms in natural freshwaters than in natural estuarine systems or seawater. 相似文献
984.
Nini Pang Jian Gao Fei Che Tong M Su Liu Yan Yang Pusheng Zhao Jie Yuan Jiayuan Liu Zhongjun Xu Fahe Chai 《环境科学学报(英文版)》2020,32(9):201-209
To investigate the cause of fine particulate matter (particles with an aerodynamic diameter less than 2.5 µm, PM2.5) pollution in the heating season in the North China Plain (specifically Beijing, Tianjin, and Langfang), water-soluble ions and carbonaceous components in PM2.5 were simultaneously measured by online instruments with 1-hr resolution, from November 15, 2016 to March 15, 2017. The results showed extreme severity of PM2.5 pollution on a regional scale. Secondary inorganic ions (SNA, i.e., NO3?+SO42+ NH4+) dominated the water-soluble ions, accounting for 30%-40% of PM2.5, while the total carbon (TC, i.e., OC + EC) contributed to 26.5%-30.1% of PM2.5 in the three cities. SNA were mainly responsible for the increasing PM2.5 pollution compared with organic matter (OM). NO3? was the most abundant species among water-soluble ions, but SO42- played a much more important role in driving the elevated PM2.5 concentrations. The relative humidity (RH) and its precursor SO2 were the key factors affecting the formation of sulfate. Homogeneous reactions dominated the formation of nitrate which was mainly limited by HNO3 in ammonia-rich conditions. Secondary formation and regional transport from the heavily polluted region promoted the growth of PM2.5 concentrations in the formation stage of PM2.5 pollution in Beijing and Langfang. Regional transport or local emissions, along with secondary formation, made great contributions to the PM2.5 pollution in the evolution stage of PM2.5 pollution in Beijing and Langfang. The favourable meteorological conditions and regional transport from a relatively clean region both favored the diffusion of pollutants in all three cities. 相似文献
986.
结合物联网技术,介绍一种智能化安全仿真实训技术,通过对培训关键控制指标的筛选以及感知元件的应用,研发了安全仿真实训项目的感知层设计方案,以及多项目间的培训状态数据匹配技术,形成了系统的智能化安全仿真实训技术方案。通过与当前普遍应用的安全仿真实训技术进行对比,该技术方案能够有效提升培训考核的客观性,提高安全仿真实训实施效率,更好满足企业需求。 相似文献
987.
988.
构建空气质量治理前后与人呼吸系统疾病患者例数的定量分析关系模型,获取呼吸系统疾病例数与空气质量的关系,通过人呼吸道疾病实证分析,明确空气质量治理前后的人呼吸系统影响变化状况。以荆州地区某中心医院收治的患有呼吸道疾病的患者为研究对象,通过为期两年的观测,结合四季空气质量治理程度的监测数据,建立呼吸系统疾病感染例数与空气质量治理程度的定量回归分析模型,结合稳健性检验分析方法,在显著度水平大于10%的条件下进行空气质量与呼吸系统疾病患者例数的统计分析,并测试人们的身体指参数,实现两者关系的定量分析。 相似文献
989.
玉米延迟型低温冷害的动态监测 总被引:13,自引:3,他引:13
利用东北3省51个气象站1961—2000年的资科分析了玉米延迟型低温冷害出现的频率,以及各发育期的进程与低温冷害的关系。结果表明:在低温冷害年,苗期、七叶期、抽雄期和成熟期拖后大于等于5天发生低温冷害的可能性分别为75%,89%,92%和100%。通过分析多年的分期播种资科,分别给出了播种到出苗、出苗到抽雄、抽雄到成熟的指标。根据这些热量指标和推算出的玉米的发育进程对其进行了动态监测,利用作物生长动态统计模型和生长动力模型进行了玉米生长量的计算,通过与高温年和正常年进行比较,即可对玉米生长量进行监测。 相似文献
990.
Thetemperatureiscrucialenvironmentalconditionforcrop'sgrowthandtoohighortoolowtemperatureisharmfultocrop'sgrowth.Guangxiliesinthetransitionbeltbetweensubtropicalareaandtropicalareawheretherearefavourableconditionsforplantingcropsandfruitsofsubtropicalandtropicalareas.Especially,inrecentyearswiththeeconomicdevelop mentofcountryandlargelyplantingoffruitsandanti seasonalvegetables,Guangxihasbecomemainfruits producingareaandcrops producingareaintropicalandsubtropicalareas.Thein vadingofcoldwaveinw… 相似文献