东北典型湖库水体对铜绿微囊藻荧光特性的影响

为考察东北典型湖库水体对铜绿微囊藻(Microcystic aeruginosa)生长过程中IDOM(细胞内溶解性有机物)荧光特性的影响,在镜泊湖、兴凯湖、五大连池、松花湖和大伙房水库5个典型湖库,共10个采样点采集水样,用于铜绿微囊藻的培养,利用EEM(三维荧光光谱)技术,结合三维荧光FRI(区域体积积分)开展IDOM荧光特性的聚类分析. 结果表明:铜绿微囊藻中IDOM的主要荧光特征峰为类蛋白荧光峰(峰S和峰T),峰S荧光强度高于峰T;对IDOM的三维荧光光谱分为5个区(Ⅰ～Ⅴ区)进行区域体积积分,荧光响应值比例(P_Ⅰ+Ⅱ,n和P_Ⅳ,n)总体上呈互补趋势;Ф_T,n(总区域体积积分)表现为镜泊湖>五大连池>兴凯湖>松花湖>大伙房水库,第16天镜泊湖的Ф_T,n最大,平均值为9.76×10-5 AU·nm2/(mg/L);大伙房水库的Ф_T,n最小,平均值为3.72×10-5 AU·nm2/(mg/L). 聚类分析将10个采样点分成3类. HJ1、HJ2采样点为类别1;HX1、LD1、JS1、LD2采样点为类别2;HX2、JS2、HW2、HW1采样点为类别3,其中,类别1(镜泊湖)水体较类别2和类别3水体更适宜铜绿微囊藻的生长.      

东北北部温带森林和干草地土壤养分分布及影响因素

土壤是陆地生态系统碳储存的重要场所,其养分变化与全球陆地碳循环密切相关。土壤养分是植物生长的重要保证,而土壤各养分之间是紧密联系的。理解土壤养分变化与环境因素的关系有助于更好地了解陆地生态系统碳、氮、磷循环。本研究以东北北部自东向西沿降水量梯度变化纬度带上的温带森林与干草地生态系统为研究对象,利用气象数据和野外土壤实测数据,分析了纬度带上不同植被类型土壤的有机碳、全氮、碳氮比、速效磷的空间分布格局及其与环境因子（年降水量、年均温、土壤pH值）的关系。研究纬度带上降水量自东向西逐渐减少,植被类型从温带森林过渡到干草原,与降水量和植被类型对应,植被生物量也自东向西呈现从高到低的分布梯度。研究结果表明：从整个研究带上来说,降水量与土壤pH值是土壤养分空间分布的决定因素,沿纬度带从东到西,随着降水量逐渐减少,土壤pH值逐渐增加,而土壤有机碳、全氮、碳氮比、速效磷含量逐渐减少。但如果将森林和草地分别讨论则发现,森林和草地生态系统的土壤养分环境控制因素有较大差别。对于草地生态系统而言,降水量和土壤pH值仍然是其土壤养分含量的控制因子,但森林生态系统由于所处区域降水量充足,降水量不再是其土壤养分的控制因子,降水量只与森林土壤碳氮比呈显著正相关。研究还发现森林土壤的速效磷含量与温度呈正相关,与土壤pH值呈负相关,说明温度对东北北部温带森林的土壤养分含量具有一定的控制作用。     

我想赶回家过节

元旦过节前一天,我接了一车货,短途。我算了一下时间,下午能赶回家过节。送货回来的路上,高速公路堵车,看着长长的车龙,我心里郁闷而躁热,不喜欢下车闲谈的我,实在坐不住了,跳下车子走到路旁跟一些货车司机攀     

东北典型黑土区农村居民点对水土流失影响研究

从人地关系视角探究典型区域农村居民点布局对生态环境的影响,对合理优化农村居民点分布格局、保障粮食安全具有重要战略意义。以东北典型黑土区克山县为例,综合运用分散度统计、核密度估计、空间关联测度模型等空间分析方法,揭示1988—2018年克山县农村居民点时空演变规律;结合修正通用RULSE模型,采用景观指数分析和广义变异系数的灰色关联度量化模型,探讨农村居民点分布特征对水土流失的影响。结果表明:(1)近30 a来,克山县农村居民点数量急剧增加,分散化趋势明显,以高密度多核心集聚、低密度广泛分布为主要空间分布特征,分布重心向东北部迁移。(2)研究区水土流失以微度、轻度和中度侵蚀为主,水土流失强度空间分布格局与农村居民点的空间分布格局呈现一致性。(3)研究区农村居民点分布特征因子与水土流失面积的关系存在差异,农村居民点分布范围与密度对水土流失具有较强作用。     

珲春东北虎何以频繁捕食家畜?

2010年适逢农历虎年,威猛的老虎形象已经充斥于大街小巷。然而对于生活于吉林省珲春国家级自然保护区内与东北虎有亲密接触的农民来说,这实在不能算一个好年。珲春东北虎国家级自然保护区成立于2001年,是我国第一个以东北虎、远东豹及其栖息地为主要保护对象的自然保护区,保护区成立后,东北虎在保护区内的活动与日俱增,这对保护区是件好事;然而,发生在保护区内的东北虎频繁捕食家畜事件令保护区的工作人员头痛不已。一头接一头的大型家畜被东北虎捕食,不仅给当地农民造成了巨大的经济损失,对其心理上的伤害也是难以形容的。     

淮河流域近50年降水异常及其大尺度环流特征

根据国家气象中心整编的全国714站月平均降水量资料,运用REOF分析、Morlet小波分析、差值分析等方法,通过对淮河流域代表站点的选取,分析了1960～2009年淮河流域降水的趋势变化特征、周期特征,以及多雨、少雨年的大气环流异常特征。结果表明：（1）淮河流域年降水总量呈缓慢增长趋势,20世纪80年代初期由负距平转为正距平。冬季和夏季降水量呈显著增长趋势,春季和秋季降水量呈显著减少趋势,80年代前期为降水变化的转折期;(2)淮河流域夏季降水存在准3 a的显著振荡周期和准10 a的次显著振荡周期,同时在60～90年代还存在准6 a振荡周期;（3）淮河流域多雨年,500 hPa经向风偏强且范围广,850 hPa上从孟加拉湾经南海向华东地区的水汽输送明显偏强,在江苏、安徽地区有水汽的正涡度辐合区;少雨年,经向风偏弱,华东地区方向的水汽输送明显减弱;（4）多雨年与少雨年的500 hPa风场差值场、高度场差值场分析表明,多雨年贝加尔湖西部和鄂霍次克海地区阻塞高压活动频繁,东北冷涡异常活跃,副高偏强,3者共同作用使得降水偏多。500 hPa温度场差值场分析表明,多雨年中国东部、华北和东北地区冷空气偏强,同时南方大部分地区暖空气也偏强,冷暖空气共同作用使降水偏多     

亿万农民的企盼——农居地震安全工程

甘肃省地处青藏块体东北缘,境内地质构造复杂,南北地震带和河西走廊祁连山地震带基本贯通全省,是中国大陆地震活动最强烈的地区之一,地震活动分布广、频度高、强度大、震源浅、震害重。全省14个市、州均发生过6级以上地震或遭受过邻区地震的波及破坏。仅20世纪90年代以来,就先后发生了1990年天祝一景泰6．2级等14次4．5级以上破坏性地震,除2002年玉门5．9级地震外,其余全都发生在农村地区。     

Pollution characteristics and health risk assessment of benzene homologues in ambient air in the northeastern urban area of Beijing, China

Ambient benzene homologues were measured at a site in the northeastern urban area of Beijing, China, from August 24 to September 4, 2012 by SUMMA canister sampling followed by laboratory determination using cryogenic cold trap pre-concentration-GC-MS/FID, and their health risks were also assessed. Daily total benzene homologues ranged from 0.99 to 49.71 μg/m3with an average of 11.98 μg/m3. Benzene homologues showed higher concentrations in the morning and evening than that at noontime. Comparison with previous studies revealed a trend of decrease for ambient benzene homologues probably due to the efective emission control in Beijing in recent years. Vehicular exhaust was the main source while volatilization of paints and solvents also made substantial contributions. Health risk assessment showed that BTEX(benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) and styrene had no appreciable adverse non-cancer health risks for the exposed population, while benzene has potential cancer risk of 1.34E-05. Available data from cities in China all implied that benzene imposes relatively higher cancer risk on the exposed populations and therefore strict control measures should be taken to further lower ambient benzene levels in China.     

Effects of elevated CO2 concentration and nitrogen supply on biomass and active carbon of freshwater marsh after two growing seasons in Sanjiang Plain, Northeast China

An experiments were carried out with treatments differing in nitrogen supply (0, 5 and 15 g N/m²) and CO₂ levels (350 and 700 μmol/mol) using OTC (open top chamber) equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO₂ concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO₂ concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO₂ elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO₂ concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply (15 g N/m²). Elevated CO₂ concentration also increased the allocation of biomass and carbon in root. Under elevated CO₂ concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon (10.6%) > dissolved organic carbon (7.5%) > labile oxidable carbon (6.6%) > carbohydrate carbon (4.1%). Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO₂ concentration.