镧掺杂TiO2/g-C3N4复合光催化剂的制备及其可见光催化活性研究

以工业二氧化钛(TiO_2)、硝酸镧(LaN_3O_9·5H_2O)、三聚氰胺(C_3H_6N_6)为原料制备了La掺杂TiO_2/g-C_3N_4复合光催化剂.采用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、傅里叶变换红外(FT-IR)、紫外-可见吸收光谱(UV-Vis)、荧光光谱(PL)等表征方法对光催化剂结构进行分析,表明复合样品中La以La~(3+)形式存在于TiO_2晶体中,并形成TiO_2/g-C_3N_4异质结构,其禁带宽度减小、吸收带边红移,光催化效率有明显提高.以亚甲基蓝为目标污染物评价其光催化活性,镧掺杂量为4%(质量分数)、煅烧温度为520℃、煅烧时间为2 h时,复合样品光催化活性最佳,在12 LED灯下,180 min后对10 mg·L~(-1)亚甲基蓝溶液的去除率达97%.     

A review of early gadiform evolution and diversification: first record of a rattail fish skull (Gadiformes, Macrouridae) from the Eocene of Antarctica, with otoliths preserved in situ

Codfishes, the Gadiformes, are quite abundant in modern temperate and polar waters with a fossil record ranging back into the Palaeogene. The oldest records are from the Danian and Selandian of Europe and South Australia. The bipolar distribution early in their evolutionary history implies that their origin must have occurred quite early in the Palaeocene, or even in the Late Cretaceous with subsequent rapid diversification. By the Eocene, gadiforms were highly abundant and widespread. With the exception of gadiforms, no Eocene Antarctic teleostean group is present in the modern Antarctic fauna. Here, we review the early evolution and diversification of gadiforms in general and of macrouroids in particular. We also describe the undoubtedly oldest skeletal macrourid specimen with otoliths preserved in situ. It is the first definitive record of this group from the Eocene of Antarctica filling a gap in its stratigraphic distribution. The fossil record of gadiforms in general and macrouroids in particular indicates that the origin of both was in shallow shelf environments but with adaptations to deep-water settings early in their evolution. While gadoids seemingly originated in the earliest Palaeogene and rapidly experienced a first major radiation event in the eastern North Atlantic and/or North Sea Basin, macrouroids evolved in the Southern Ocean and migrated northwards into the South Atlantic before the establishment of the circum-Antarctic current and subsequent isolation of the Antarctic fish fauna. These two timely and regional separated adaptive radiation events in the Palaeogene gave rise to their modern taxonomic diversity and global distribution.     

土壤中La与P迁移的关联性初步研究

通过室内土柱淋溶试验和人工降雨模拟试验分别观察了元素P和La从土壤表层纵向和横向流失的特征,初步探讨了单一稀土元素La与土施畜禽肥料P随暴雨径流流失的关联性.淋溶试验结果表明,外源La和P在土壤中的纵向迁移都非常困难,La和P的迁移深度分别不超过土壤表层6 cm和8 cm;增加外源La可以降低土壤中水浸提P、NaHCO3浸提P和NaOH浸提P的量,提高HCl浸提P的量,增加残渣态P在TP中的比重;而人工降雨模拟试验结果表明,绝大部分La和总P都是通过径流沉积物相流失(占流失总量的95%以上),对于添加不同剂量的La系列,无论是从土壤表层的流失速率还是流失的总量,总P和La都存在良好的相关性.     

金属离子掺杂TiO_2薄膜光催化去除气相中甲醛

采用溶胶-凝胶法在普通玻璃表面制备TiO2,Fe3+/TiO2,La3+/TiO2三种光催化剂,研究了煅烧温度、煅烧时间、涂膜层数、Fe3+和La3+加入量等因素对光催化剂降解气相甲醛的影响。结果表明,La3+/TiO2光催化性能略好于TiO2,Fe3+/TiO2光催化性能最佳。当掺Fe3+的TiO2催化剂煅烧温度为450℃,煅烧时间为2h,Fe:T(imol)=0.3%,涂覆层数为4层,光催化反应3h,实验封闭体系中甲醛的降解率可达49.24%。     

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.     

Effects of La,Ce on nitrogen removal in sequencing batch reactor

Batch experiments were conducted to study the short-term biological effects of rare earth ions (La³⁺, Ce³⁺) and their mixture on the nitrogen removal in a sequencing batch reactor (SBR). The data showed that higher NH⁺₄―N removal rate, total inorganic nitrogen removal efficiency, and denitrification efficiency were achieved at lower concentrations of rare earth elements (REEs) (<1mg/L). In the first hour of the aeration stage of SBR, the presence of REEs increased the total inorganic nitrogen removal efficiency and NH⁺₄―N removal efficiency by 15.7% and 10%―15%, respectively. When the concentrations of REEs were higher than 1mg/L, the total inorganic nitrogen removal efficiency decreased, and nitrate was found to accumulate in the effluent. When the concentrations of REEs was up to 50.0mg/L, the total inorganic nitrogen removal efficiency was less than 30% of the control efficiency with a high level of nitrate. Lower concentrations of REEs were found to accelerate the nitrogen conversion and removal in SBR.     

镧(La)-甘氨酸(Gly)稀土配合物对酸雨伤害植物的影响

用３０ ｍｇ Ｌ－ １ ＬａＧｌｙ 处理鸡爪槭１ 次,可减轻ｐＨ３．５ 酸雨对鸡爪槭造成的伤害．实验结果显示,此与ＬａＧｌｙ 提高鸡爪槭叶片光合速率,叶绿素含量,减少丙二醛含量,降低细胞质膜透性,维持细胞汁ｐＨ 值稳定性与过氧化氢酶、过氧化物酶及脱氢酶活性等多重生态生理效应相关．     

FROM FLOW TO FISH TO DOLLARS: AN INTEGRATED APPROACH TO WATER ALLOCATION1

This paper details a case study of economic and natural system responses to alternative water management policies in the Cache La Poudre River basin, Colorado, 1980–1994. The case study is presented to highlight the value and application of a conceptual integration of economic, salmonid population, physical habitat, and water allocation models. Five alternative regimes, all intended to increase low winter flows, were investigated. Habitat enhancements created by alternative regimes were translated to population responses and economic benefits. Analysis concluded that instream flows cannot compete on the northern Colorado water rental market; cooperative agreements offer an economically feasible way to enhance instream flows; and establishing an instream flow program on the Cache La Poudre River mainstem is a potentially profitable opportunity. The alliance of models is a dynamic multidisciplinary tool for use in professional settings and offers valuable insight for decision-making processes involved in water management.     

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.