近30a来白洋淀土地利用变化规律及驱动力分析

分析土地利用变化规律对提高土地开发利用效率和推动生态环境保护工作具有重要意义。针对白洋淀的土地利用演变,为探究其变化趋势,以白洋淀湿地为例,采用30 a来8期Landsat TM/OLI遥感影像为数据源,结合遥感和地理信息系统方法,分析白洋淀湿地土地利用的时空变化特征和驱动力。结果表明:(1)1986—2018年,主导的土地利用类型是耕地和水域。耕地变化最为明显,减少了60.3%,水域变化次之,增加了24.1%。水生植物面积大致呈增多—减少—增多的趋势,居民地面积持续增加。(2)分析土地利用动态度得出,1986—2018年间水生植物和水域面积的单一动态度较大,综合动态度(L_C)从0.267%下降到0.117%,呈现缓慢下降趋势,说明白洋淀土地利用到后期的变化速度变慢,土地利用状态趋于稳定。(3)白洋淀土地利用类型变化的驱动因子为气候、人类活动和国家宏观政策。研究成果有利于区域进行土地利用决策,也可作为土地可持续利用和生态环境保护的科学依据。     

白洋淀府河入淀口周边水质空间变异特征分析

为探明府河入淀对白洋淀的水质影响,摸清区域水质现状,运用克里格插值法和主成分分析法,揭示了白洋淀流域府河入淀口段区域水质在汛期的空间变异特征。结果表明,白洋淀府河入淀口水域自入淀口向湖心方向,总磷等5项水质指标浓度值均呈减小趋势,近府河入淀口处为高浓度带,其面积均约为总研究区域面积一半以上;氨氮和亚硝酸盐氮浓度变化大,变异系数均大于40%;总磷和氨氮浓度均值分别超出国家地表水环境Ⅴ类标准的2.63、0.54倍,属重度污染区域,府河来水携带污染物严重超标;汛期入淀口区域氮素污染物浓度呈增大趋势,主要是由于淀西平原的农业面源污染引起。该研究方法可用于评价该区域水质状况,研究成果为改善该区域水质状况提供了依据。     

AHP法在引黄入冀补淀工程移民安置评估中的应用

为克服传统移民安置评估方法的缺点,选取引黄入冀补淀移民安置评估项目进行研究。评估结合项目特点和以往经验从收支、生产、居住以及人口素质四个方面,选取了12个常用指标建立了移民安置评估指标体系。在调查时,着重收集这些指标数据,评估时采用AHP法对所选取的评价指标进行权重计算并得出了指标重要程度的排序。最后,对这些关键指标的前后变化情况开展了比较分析。从分析结果上来看,AHP法所反映出来的重要指标同项目的特点及移民关注点吻合,分析过程客观。该方法可为移民安置评估工作提供参考。     

Cold-humid effect of Baiyangdian wetland

Data support for wetland protection function evaluation can be provided by quantitatively analyzing the ability of regulating the regional climate of the wetland ecosystem. In this study, the cold-humid effect of the Baiyangdian wetland was analyzed by comparing the meteorological conditions of the Baiyangdian wetland and its surrounding areas. Meanwhile, the regulatory functions of the Baiyangdian wetland for the processes and magnitudes of temperature and relative humidity from August to October 2008 were evaluated. The results show that daily mean temperatures in the Baiyangdian wetland were lower than in the surrounding areas, and that temperature differences mainly occurred in the daytime but were not obvious at night. Diurnal temperature ranges in the Baiyangdian wetland were lower than in the surrounding areas, and the higher the diurnal temperature range in the surrounding areas was, the stronger the regulation ability of the Baiyangdian wetland. Compared with the surrounding areas, the decline of the daily minimum temperature in the Baiyangdian wetland was gentler, and the mean relative humidity there was higher. The present findings indicate that effects of the Baiyangdian wetland on climate and humidity regulation are significant.     

Distribution,Sources, and Risk of Polycyclic Aromatic Hydrocarbons in the Core Sediments from Baiyangdian Lake,China

The burial characteristics and risks of 16 polycyclic aromatic hydrocarbons (PAHs) in core sediments from Baiyangdian Lake were investigated through gas-chromato graphy/mass spectrometry. The total concentrations of the 16 PAHs ranged from 39.48–1877.75 ng g^?1. The low-molecular-weight PAHs (two- to three-ring PAHs) were the dominant species, contributing 40.10–92.18% to the total PAHs, with a mean of 71.01%. Based on the observed molecular indices and on principal component analysis, the PAHs inputs were initially dominated by biomass and coal combustion, and atmospheric deposition and surface runoff could be the major transport pathways. The contaminated source characteristics, hydrodynamic condition, and sediment textural composition are the key factors affecting the distribution and source of PAHs. By conducting a risk quotient analysis between specific PAH concentrations and their corresponding sediment quality values, the top layer sediments were found to have a potential biological impact and relatively high toxicity. However, such impact should have no impairment. The toxic potency of PAHs in Baiyangdian Lake could be described by using the toxic equivalent of benzo[a]pyrene.     

白洋淀生态环境的现状与治理保护

白洋淀作为华北最大的淡水湖,水域面积锐减,随着最近几十年连续出现干淀现象及大量污水进入白洋淀,白洋淀生态环境遭到严重破坏.2005年,河北省启动一项历时10年、总投资达80亿元的白洋淀生态环境治理计划,以恢复白洋淀的生态环境.文章从白洋淀的生态环境恶化的原因的角度来分析白洋淀的现状并提出治理和保护措施.     

引黄入冀补淀工程对地表水环境影响预测

为缓解河北省地下水超采状况及向白洋淀实施生态补水,修建引黄入冀补淀工程。利用所建位山引黄入冀工程模型相关试验参数及其他相关研究成果对研究设置的6个情景方案进行了模拟分析,研究此次工程对输水沿线及受水区白洋淀的地表水环境影响。结果表明:在实施输水沿线水污染治理后,多年平均情况下,当引水口水质满足其水功能区水质目标要求时,输水沿线各断面水质除TN外可达到Ⅲ类水质标准,引黄入冀补淀工程可有效改善沿线及入白洋淀地表水环境。由运行初期所存在的问题建议入白洋淀断面设置水质自动监测站,一旦水质超标应立即停止向白洋淀引水,确保初期输水安全。     

基于SWAT模型的白洋淀流域总氮负荷模拟研究

在白洋淀水质现状评价的基础上,以营养元素总氮为指示因子,用SWAT模型分析白洋淀流域污染负荷影响因素,模拟各类污染源的贡献值及分布。结果表明,相对于环境背景值,添加面源或点源排放后,总氮负荷分别增加了64%和116%。白洋淀流域总氮多年平均面源负荷贡献率为33.8%,点源负荷贡献率为66.2%,且汛期总氮负荷量远高于非汛期。     

白洋淀湿地入淀水量演变归因分析

以白洋淀水文数据为基础,采用敏感系数法,分析了气候变化、人工取用水及蒸渗过程改变对入淀水量变化的影响。在研究时段内,湿地入淀水量、流域降水量及潜在蒸散发量都呈下降趋势,其中入淀水量下降尤为明显。气候变化、人工取用水及蒸渗过程改变对入淀水量变化的影响分别为25.1%、57.53%和17.4%,而人类活动整体对入淀水量影响达到了74.9%,因此人类活动是入淀水量减少的主要原因。     

围隔生态系统对白洋淀水体富营养化的影响

为控制白洋淀的水体富营养化状况,在所选实验水域建立由不同类型的食物链组成的围隔生态系统。从2010年8月份到10月份每周采样一次,共8次,测定水体中的pH、溶解氧(DO)、透明度(SD)、高锰酸盐指数(CODMn)、总氮(TN)、氨氮、总磷(TP)、叶绿素a的浓度,研究围隔生态系统对于水质的影响作用。实验结果表明:实验初期围隔内水质明显好转,富营养化程度降低。在各个实验组中金鱼藻组对于水质的改善作用最为明显,对SD、DO、CODMn、TP、TN、NH 4+-N、叶绿素a等水质指标的改变率分别达到192%、204%、73.8%、21.3%、56.0%、75.0%、28.6%,使水体的富营养化指数减低为初始值的74%。