大气中γ辐射空气吸收剂量率的波动机制

基于广西防城港市、福建福清市和宁德市的3个滨海核电厂周边γ辐射空气吸收剂量率长时间高频率的连续观测数据,从不同时间尺度进行系统解析.研究发现,在年际尺度上,2014～2020年间宁德嵛山岛站位γ辐射空气吸收剂量率呈现先上升后下降的趋势,与太阳活动的先减弱后增强存在一定的反相位关联;在季节尺度上,2019年度3个站位的观...     

AnSBR法处理生活污水中典型环境雌激素的研究

为评价和考察厌氧序批式反应器(AnSBR)对生活污水中9种典型环境雌激素的去除效果和机制,采用固相萃取(SPE)——LC/MS/MS分析方法,分析所选环境雌激素的浓度和污泥吸附量. 结果表明:大豆苷元,4-t-辛基酚(OP),4-n-壬基酚(NP)和染料木素的检出浓度高于其他5种环境雌激素;厌氧污泥对NP,OP,雌酮(E1),17α-乙炔基雌二醇(EE2)和17β-雌二醇(E2)的吸附作用明显;大豆苷元和染料木素的去除率在60%以上;大豆苷元、染料木素和雌三醇(E3)的主要去除机制为生物降解作用,EE2,OP和NP的去除是生物降解、污泥吸附的共同作用.      

Time stress,predation risk and diurnal–nocturnal foraging trade-offs in larval prey

Insect larvae increase in size with several orders of magnitude throughout development making them more conspicuous to visually hunting predators. This change in predation pressure is likely to impose selection on larval anti-predator behaviour and since the risk of detection is likely to decrease in darkness, the night may offer safer foraging opportunities to large individuals. However, forsaking day foraging reduces development rate and could be extra costly if prey are subjected to seasonal time stress. Here we test if size-dependent risk and time constraints on feeding affect the foraging–predation risk trade-off expressed by the use of the diurnal–nocturnal period. We exposed larvae of one seasonal and one non-seasonal butterfly to different levels of seasonal time stress and time for diurnal–nocturnal feeding by rearing them in two photoperiods. In both species, diurnal foraging ceased at large sizes while nocturnal foraging remained constant or increased, thus larvae showed ontogenetic shifts in behaviour. Short night lengths forced small individuals to take higher risks and forage more during daytime, postponing the shift to strict night foraging to later on in development. In the non-seasonal species, seasonal time stress had a small effect on development and the diurnal–nocturnal foraging mode. In contrast, in the seasonal species, time for pupation and the timing of the foraging shift were strongly affected. We argue that a large part of the observed variation in larval diurnal–nocturnal activity and resulting growth rates is explained by changes in the cost/benefit ratio of foraging mediated by size-dependent predation and time stress.     

Rates of Movement of Threatened Bird Species between IUCN Red List Categories and toward Extinction

Abstract:  In recent centuries bird species have been deteriorating in status and becoming extinct at a rate that may be 2–3 orders of magnitude higher than in prehuman times. We examined extinction rates of bird species designated critically endangered in 1994 and the rate at which species have moved through the IUCN (World Conservation Union) Red List categories of extinction risk globally for the period 1988–2004 and regionally in Australia from 1750 to 2000. For Australia we drew on historical accounts of the extent and condition of species habitats, spread of invasive species, and changes in sighting frequencies. These data sets permitted comparison of observed rates of movement through the IUCN Red List categories with novel predictions based on the IUCN Red List criterion E, which relates to explicit extinction probabilities determined, for example, by population viability analysis. The comparison also tested whether species listed on the basis of other criteria face a similar probability of moving to a higher threat category as those listed under criterion E. For the rate at which species moved from vulnerable to endangered, there was a good match between observations and predictions, both worldwide and in Australia. Nevertheless, species have become extinct at a rate that, although historically high, is 2 (Australia) to 10 (globally) times lower than predicted. Although the extinction probability associated with the critically endangered category may be too high, the shortfall in realized extinctions can also be attributed to the beneficial impact of conservation intervention. These efforts may have reduced the number of global extinctions from 19 to 3 and substantially slowed the extinction trajectory of 33 additional critically endangered species. Our results suggest that current conservation action benefits species on the brink of extinction, but is less targeted at or has less effect on moderately threatened species.     

温度对奶牛粪便温室气体排放的影响

采用封闭罐-气相色谱法对4种不同温度处理下奶牛粪便温室气体排放速率进行测定.结果表明,温度是影响奶牛粪便温室气体排放的主要因子,温度较低时奶牛粪便温室气体排放速率低,而且随着奶牛粪便处理温度升高而增大.在5、15、25和35℃4个处理中,奶牛粪便CO2排放速率两两之间差异显著;CH4排放速率除了5和15℃处理差异不显著之外,其他两两处理之间差异显著;35℃处理时N2O排放速率与其他温度的排放速率差异均显著,其他两两处理之间差异不显著.     

阿特拉津对铜绿微囊藻和四尾栅藻生长的影响

在实验室内利用MA培养液培养,通过测定藻生长量和叶绿素a含量,研究不同浓度下的阿特拉津对铜绿微囊藻(Microcystis aeruginosa)和四尾栅藻(Scenedesmus quadricauda)生长的影响,并以藻细胞数表示的最大比生长率为指标,评价2种藻对阿特拉津的敏感性.结果表明,在0.001～5.000 mg·L-1质量浓度范围内,阿特拉津对铜绿微囊藻和四尾栅藻的生长表现出低浓度刺激、高浓度抑制的效应,且阿特拉津对四尾栅藻的刺激效应明显大于铜绿微囊藻.     

芦苇化感物质EMA对铜绿微囊藻生理特性的影响

研究了芦苇产生的化感物质2-甲基乙酰乙酸乙酯(EMA)对铜绿微囊藻呼吸作用、光合作用和抗氧化酶体系的影响.结果表明,在实验条件下,EMA能提高铜绿微囊藻的呼吸速率,使培养瓶中的CO₂浓度升高;降低铜绿微囊藻的光合作用速率,促进了铜绿微囊藻叶绿素a的降解,使其含量降低;较低浓度的EMA提高了铜绿微囊藻的过氧化物酶、超氧化物歧化酶和脱氢酶的活性,而更高浓度的EMA则显著降低了这些酶活性(α=0.05).高浓度EMA抑制铜绿微囊藻的抗氧化酶体系并促进藻类叶绿素的降解可能是其抑藻机理之一.     

速度场常数及其自动检测装置

通过对烟道“速度场常数”的研究,提出利用速度场常数监测烟道烟气平均流速的方法,同时研制出速度场常数自动检测装置。解决烟道烟气平均流速自动监测的技术难题。     

长江中下游浅水湖泊沉积物对磷的吸附特征

研究了长江中下游浅水湖泊1 1个沉积物对磷的吸附等温线及其吸附动力学,并分析了沉积物理化特征对磷吸附特征的影响,研究发现:①沉积物对磷酸盐的吸附主要在前1 0h内完成,在0.5h内吸附反应十分迅速,并逐渐达到吸附平衡;②沉积物本底吸附态磷与其有机质、CEC、总磷、无机磷、有机磷、Fe/Al 磷和总氮显著正相关;对磷酸盐的最大吸附量与其CEC和无机磷、有机质和总磷呈显著负相关;而总最大吸附磷量与其有机质、CEC、总磷、无机磷、有机磷、Fe/Al 磷和总氮含量呈显著正相关;③就目前长江中下游浅水湖泊的水质而言,其沉积物存在解析;沉积物对磷酸盐的吸附 解吸平衡浓度与其有机质,CEC ,总氮,总磷以及各形态磷含量均有显著的正相关关系.本研究条件下,即使是污染较为严重的湖泊,其沉积物也具有向上覆水体释磷酸盐的趋势.     

蒽的不完全臭氧氧化及中间产物特性分析

对蒽进行了臭氧不完全氧化实验研究,利用HPLC、UV、TOC监测了臭氧氧化过程中发生的变化.结果表明,蒽被臭氧降解时有中间产物生成,臭氧可以与中间产物继续作用,但是难以使之矿化.另外,氧化体系中水溶性有机物的TOC变化及其对活性污泥OUR的影响结果表明,臭氧氧化改善了蒽的可生化降解性.因此,臭氧氧化与生物降解组合技术,有望成为处理废水中蒽的经济有效方法.