镧对微囊藻的生长效应及被富集的动力学研究

研究了稀土元素La3 对微囊藻生长效应及其被微囊藻富集的动力学过程 .结果表明 :当La3 的添加浓度小于 2mg·l- 1 时 ,对微囊藻的生长有促进作用 ,当La3 的添加浓度大于 2mg·l- 1 时 ,微囊藻的生长受到抑制 .La3 在微囊藻中富集的动力学过程可用表面配位模型表征     

ENSO与云南蒋家沟泥石流灾害发生的关系

通过分析近40年来出现的ENSO事件对云南东川蒋家沟泥石流活动的影响可知,El Ni(~n)o与LaNi(~n)a对其的影响正好相反,且El Ni(~n)o的影响大于La Ni(~n)a的影响.El Ni(~n)o年,泥石流年发生频次、径流量和输沙量偏少的概率均较大,泥石流活动减弱的倾向明显;La Ni(~n)a年,虽有一定的对应关系,但不如El Ni(~n)o年明显,且影响更复杂一些,总的来说,泥石流年发生频次、径流量和输沙量偏多或持平的概率较大.     

阿拉善地区生态环境问题及探讨

阿拉善荒漠地处我国西北内陆，亚洲荒漠区最东部，总面积27万平方公里。由于所处的特殊地理位置，阿拉善荒漠植被，历来成为甘肃河西走廊、宁夏平原和内蒙古河套平原三大绿洲的天然保护屏障。然而，阿拉善地区的生态环境日趋恶化，气候干旱、沙尘暴频繁、黑河下泻水量锐减，水资源危机，造成湖泊干涸，地下水位下降，水质恶化，土地盐渍化加重。成为我国沙尘暴主要尘源地区之一。植被严重衰退，生物多样性减少。草地面积缩小，保护功能强大的乔、灌、草植被，每年以2万亩的速度减少消失。绿洲萎缩，濒临消亡，濒危物种亟待抢救。沙漠化面积扩大，吞并草场，埋没农田。每年以1000平方公里速度扩张，沙进人退现象加重，生态难民增多。著名的巴丹吉林，腾格里，乌兰布和三大沙漠向前推进，倾入黄河，阻断公路、铁路、吞食盐场，直接经济损失巨大。阿拉善的生态危机和居延绿洲的严重衰退，直接影响到国防和航天建设。也威胁到了相邻省区以及黄土高原的工农业生产，甚至波及到华北、西北，以及更远的江淮地区。本地区的生态环境问题，已不是区域性的环境问题。是全社会、全民族的问题，已引起国家及各部门的高度重视。     

El Niño‐Southern Oscillation,rainfall variability and sustainable agricultural development in the Ho Municipality,Ghana

El Niño‐Southern Oscillation (ENSO), which occurs in the Equatorial Pacific Ocean, has been identified to have significant influence on rainfall variability throughout the world, especially in the tropics. Such variability in rainfall has implications for agrarian economies, such as that in Ghana. This study therefore sought to demonstrate the effect of ENSO‐induced variability in annual and seasonal rainfall on the development of sustainable agriculture in the Ho Municipality of Ghana. Using 61 years of monthly rainfall data (1955–2015) for the Ho Municipality and ENSO indices, this study showed that 15% of the variability in total annual rainfall is explained by the ENSO phenomena. Mean annual rainfall and rainfall in the major rainy season decreased for El Niño years, in addition to a more variable rainfall compared to that received in La Niña years. The major growing season was observed to be longer in La Niña years and shorter in El Niño years. This means that the potential for crop cultivation will be severely hampered in an El Niño year. Farmers within the municipality are therefore encouraged to harness other complementary water sources for farming activities and also employ water management strategies during El Niño years.     

镧改性ZnO-TiO_2光催化氧化活性染料的实验研究

采用溶胶-凝胶法制备掺杂Zn O的Ti O2复合半导体,用X射线衍射和电镜扫描对晶体结构进行表征,最优的锌掺杂量、镧掺杂量、煅烧温度分别为3%,0.3%,500℃。以活性染料配水作为目标降解物,考察了对6种不同活性染料的光催化氧化效果。0.3%镧改性Zn O-Ti O2对活性艳蓝X-BR的色度去除率可以达到97.3%,得到最佳脱色率的条件是使用紫外光作为光源,光照时间2 h,初始质量浓度100 mg/L,p H值控制在1左右,氯离子浓度控制在1 mol/L。     

Exponential Collapse of Benthic Depurative Capacity in A Eutrophic Tropical Marine Ecosystem: A Threshold Response to Organic Nitrogen Loading

Microbial decomposition of particulate organic matter in sediments can substantially modulate eutrophication of nearshore marine environments. Flux budgets for nitrogen compounds and quantification of rates of microbial transformation can provide important information on the process of eutrophication. This survey documents sediment nitrogen budgets for a eutrophic nearshore marine environment at La Parguera on southwest coast of Puerto Rico, including consideration of the organic fraction in addition to microbial transformations.

Sediments of the inshore channel at La Parguera denote the input of heavy organic loads with low redox potentials and high ammonium contents. Benthic fluxes of dissolved organic nitrogen are below those recorded for ammonium. These observations suggest that nearshore tropical sediments subject to heavy nitrogen loads act as a sink for organic nitrogen and that ammonification is a key process in the release of nitrogen from sediments to the water column. Nitrification and denitrification rates are low overall and inversely related to the redox potential. Depuration of excess nitrogen through denitrification is ineffective in these sediments. in contrast to more robust temperate environments, our work demonstrates that tropical marine systems are particularly susceptible to eutrophication given their limited capacity for depuration of excess nitrogen.     

La/Ce-codoped Bi2O3 composite photocatalysts with high photocatalytic performance in removal of high concentration dye

A series of La/Ce-codoped Bi_2O_3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N_2 physical adsorption, X-ray powder diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM), UV–Vis diffuse reflectance(UV–Vis DRS), Fourier transform infrared spectroscopy(FT-IR),photoelectrochemical measurements, and photoluminescence(PL) spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi_2O_3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi_2O_3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi_2O_3 displayed much higher photocatalytic performance than that of bare Bi_2O_3, single La or Ce doped Bi_2O_3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons(e~-) and holes(h~+).     

Study on preparation and microwave absorption property of the core-nanoshell composite materials doped with La

Microwave absorbing material plays a great role in electromagnetic pollution controlling, electromagnetic interference shielding and stealth technology, etc. The core-nanoshell composite materials doped with La were prepared by a solid-state reaction method, which is applied to the electromagnetic wave absorption. The core is magnetic fly-ash hollow cenosphere, and the shell is the nanosized ferrite doped with La. The thermal decomposition process of the sample was investigated by thermogravimetry and differential thermal analysis. The morphology and components of the composite materials were investigated by the X-ray diffraction analysis, the microstructure was observed by scanning electron microscope and transmission electron microscope. The results of vibrating sample magnetometer analysis indicated that the exchange-coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating, which caused outstanding magnetic properties. The microwave absorbing property of the sample was measured by reflectivity far field radar cross section of radar microwave absorbing material with vector network analyzer. The results indicated that the exchange-coupling interaction enhanced magnetic loss of composite materials. Therefore, in the frequency of 5 GHz, the reflection coefficient can achieve ?24 dB. It is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption.     

运用关联度分析硒镧复合作用下巴西蘑菇氨基酸含量与砷含量的关系

通过采用混合培养料试验、日立8810型氨基酸自动分析仪和原子吸收法测定氨基酸含量和砷含量以及灰色系统理论分析关联度,研究了硒镧复合作用下巴西蘑菇子实体氨基酸含量和砷含量的变化和关系,为栽培砷含量低的巴西蘑菇提供科学依据.各硒镧复合处理的关联度排序为:B4>B1>B2>B0>B3.其中B4处理关联度最大,为0.835 1,B2最小,为0.726 9,说明硒镧浓度对巴西蘑菇子实体各氨基酸含量与砷含量有一定影响.各氨基酸含量与重金属砷含量关联度顺序为:丙氨酸>酪氨酸>胱氨酸>苯丙氨酸>赖氨酸>组氨酸>天门冬氨酸>异亮氨酸>苏氨酸>缬草氨酸>亮氨酸>甘氨酸>脯氨酸>精氨酸>丝氨酸>谷氨酸>甲硫氨酸.其中丙氨酸含量与砷含量关联度最大,为0.856 6,说明硒镧复合作用下巴西蘑菇子实体中丙氨酸含量与重金属砷含量的关系最为密切;关联度最小的是甲硫氨酸.     

稀土La3+掺杂Bi2WO6光催化降解活性艳红X-3B的研究

采用水热合成法制备稀土元素La3+掺杂Bi2WO6光催化剂并考察其对染料废水中活性艳红X-3B的光催化活性.通过X射线衍射、场发射扫描电镜、紫外-可见漫反射光谱、N2物理吸附-脱附等手段对合成材料的结构、形貌、光吸收等物理化学性能进行表征.结果表明,La3+掺杂量为5%时,其结晶度好、颗粒均匀、具有较强的可见光吸收性能,且比表面积比纯Bi2WO6提高30%以上,对X-3B的去除效果最好.另外,催化剂投加量、X-3B初始浓度、反应溶液pH等因素对La3+掺杂Bi2WO6光催化降解X-3B均有重要影响.