Cadmium distribution in rice plants grown in three different soils after application of pig manure with added cadmium

A glasshouse pot experiment was conducted to investigate Cd concentrations in the aboveground parts of two consecutive crops of rice and Cd availability in three different soils (loam, silt loam, and sandy loam) after application of pig manure with added Cd. Soil pH tended to increase with increasing application rate of pig manure from 1 to 3% (w/w, oven dry basis). Soil diethylene triamine pentaacetic acid (DTPA) extractable Cd showed a clear positive correlation with soil total Cd content and increased with increasing Cd amendment of the manure but showed no difference between the two manure application rates. Cd concentrations in the grain, husk, and straw were significantly and positively correlated with soil DTPA-extractable Cd (p < 0.001). Within each level of manure Cd, the higher rate (3%) of manure produced lower Cd concentrations in the grain, husk, and straw on all three soils than did the lower rate (1%) after the first crop, but this no longer occurred after the growth of the second crop. Grain Cd concentrations exceeded the Chinese National Food Quality Standard (0.2 mg kg(-1)) most often on the loam, with intermediate frequency on the silt loam, and least often on the sandy loam, the soil with the highest pH and lowest organic carbon content and cation exchange capacity.     

RBCA、CLEA及CalTOX模型在苯并[a]芘污染场地健康风险评估中的应用比较

为探讨不同模型对污染场地健康风险评估结果的影响,以苯并[a]芘为例,采用RBCA、CLEA和CalTOX模型对某工业污染场地表层土壤进行健康风险评估,分析了评估结果的差异和原因,同时对模型的主要暴露参数进行了敏感性分析,并推导出基于风险概率分布的土壤修复限值。结果表明,RBCA、CLEA和CalTOX模型计算的苯并[a]芘致癌总风险分别为2.40×10-4、6.32×10-4和7.04×10-6,且经口摄入和皮肤接触2个途径对人体健康造成的危害最大。降解作用是影响CalTOX模型风险评估结果不同于RBCA和CLEA模型的重要因素,3个模型间参数取值及方法学的差异也会导致风险评估结果不同。各模型暴露参数的敏感性排序也有差异。采用基于风险概率分布的方法推导土壤修复限值,RBCA、CLEA和CalTOX模型所得结果分别为0.18、0.08、0.13(不考虑降解作用CalTOX模型)和10.74(考虑降解作用CalTOX模型)mg·kg-1,为各模型直接推导值的1.5～2.6倍。基于风险概率分布的方法可有效降低风险评估过程中参数不确定性的影响,为工业污染场地土壤修复值的制定提供参考。     

环境雌激素o,p′-DDT和抗雌激素氟维司群对斑马鱼胚胎的复合效应

为探究雌激素与抗雌激素的复合效应,将斑马鱼(Danio rerio)的胚胎暴露于o,p′-DDT和氟维司群2种典型的环境内分泌干扰物中,考察胚胎孵化率、孵化时间和总畸形率,并用实时荧光定量PCR技术检测Vtg1、Vtg2和ERα等雌激素效应相关基因的mRNA转录水平.结果显示,与单一化合物的暴露相比,o,p′-DDT和...     

1957-2009年黄土高原地区风速变化趋势

用88个气象站1957-2009年的月平均风速和最大风速日值资料,采用距平累积法、 5 a趋势滑动法、 Mann-Kendall趋势检验法等分析了黄土高原地区风速的变化趋势及其空间分异等特征。结果表明:①黄土高原地区1957-2009年多年平均风速为2.36 m/s,水蚀区、 水蚀风蚀交错区和风蚀区年均风速分别为2.36、 2.17、 2.60 m/s,年际变化倾向率分别为-0.008 4、 -0.009 4和-0.018 8 m·s^-1·a^-1,并均通过了0.001的极显著性检验。3个区域均是冬、 春季的平均风速对全年趋势演变贡献率较大,年均风速也均在1981年发生偏强转为偏弱的跃变,20世纪70年代以后平均风速逐渐减小。②黄土高原平均风速减少的主要原因是最大风速为5级或5级以上的发生日数减少。大风频率从1970年代至2000年代呈显著减少趋势,风蚀区减少幅度最大,减少了10%以上,水蚀风蚀交错区减少1%~5%,到2000年代,大多数站点的大风频率均降低为<2%。③水蚀风蚀交错区和风蚀区年均大风日数较多,而水蚀区和黄土高原西部地区年均大风日数较少。根据大风年均发生日数,将大风天气划分为大风天气较少区(年均大风日数<10 d)、 较多区(10~50 d)、 多发区(50~100 d)和频发区(>100 d)。大风较多区在黄土高原地区分布最广,其次是较少区,无频发区。70年代至90年代,风蚀区和水蚀风蚀交错区的站点大多为大风较多区,其中70年代中宁和包头为大风多发区;2000年代以后,大部分地区转为大风较少区。     

Effects of two different intercropping systems on arbuscular mycorrhizal fungal colonization and polychlorinated biphenyl (PCB) dissipation北大核心CSCD

Polychlorinated biphenyls (PCBs) are typical organic contaminants in the environment. It is indicated that plants and soil microorganisms have a positive synergistic effect on the remediation of PCB-contaminated soil. To investigate the effect of intercropping on arbuscular mycorrhizal (AM) fungal colonization and PCB remediation, a pot-cultivation experiment with two intercropping treatments, corn (Zea mays L.) / ryegrass (Lolium perenne L.) and corn/alfalfa (Medicago sativa L.), and a corn monoculture was conducted in a greenhouse. All treatments were inoculated with Funneliformis mosseae M47V. Plant biomass, root mycorrhizal colonization rate, concentration of PCBs and their homologs in soil, 16S rDNA gene abundance, and community composition measured by Terminal Restriction Fragment Length Polymorphism (T-RFLP) were determined after harvesting the plants. Intercropping significantly increased the root mycorrhizal colonization rate and plant biomass of corn (P < 0.05), as well as the available N content of the soil. A significant difference of the bacterial community composition was found among different treatments (P < 0.05). Compared with corn monoculture, corn/alfalfa intercropping significantly increased soil bacteria abundance (P < 0.05). The dissipation rates of total PCBs, as well as that of penta-chloro biphenyls were significantly increased in the intercropping treatments, when compared to the corn monoculture treatment. Moreover, corn/ryegrass intercropping has a significantly positive effect on the dissipation of tri-chloro biphenyls. Non-metric multidimensional scaling (NMDS) analysis indicated that the PCBs homologues composition were significantly correlated with the relative abundance of 128 bp and 148 bp T-RFs. Corn intercropping with ryegrass or alfalfa has a positive effect on root mycorrhizal colonization rate and plant biomass of corn. Inoculation of AM fungi in intercropping treatments significantly improved the efficiency of PCB remediation by promoting bacterial abundance and shifting the bacterial community composition. In conclusion, intercropping combined with AM fungi have positive synergistic effects on the remediation of PCB-contaminated soils. © 2018 Science Press. All rights reserved.     

北京不同污染天气PM_(2.5)和PM_(10)染毒对大鼠生理病理参数的影响

为探讨北京不同污染天气大气可吸入颗粒物PM_(10)和细颗粒物PM_(2.5)污染对雄性大鼠血常规、氧化损伤、炎症反应和肺组织的影响,将64只雄性8周龄Wistar大鼠随机分为8组,分别为2个对照组(空白组和生理盐水组)和6个染毒组(清洁、雾霾及沙尘暴3种不同天气的PM_(10)染毒组和PM_(2.5)染毒组),每组8只。用2015年3月—5月在北京南海子麋鹿苑采集的清洁、雾霾和沙尘暴3种不同天气的PM_(10)和PM_(2.5)制备悬液,分别采用气管滴入PM_(10)和PM_(2.5)悬液作为染毒组,空白对照组不做任何处理,生理盐水对照组采用气管滴注生理盐水。急性染毒24 h后处死大鼠。采集血液测定18个血常规指标,分析肺泡灌洗液(BALF)中转化生长因子-β1(TGF-β1)、乳酸脱氢酶(LDH)、总抗氧化能力(T-AOC)、白介素-6(IL-6)及肿瘤坏死因子-α(TNF-α)的含量,并在高倍显微镜下观察肺组织和气管病理形态变化。同时,对PM_(10)和PM_(2.5)中的水溶性离子、有机碳/元素碳、16种多环芳烃和7种重金属等元素进行了测定,并分析了各组分与大鼠生理病理指标的相关性。结果表明:清洁、沙尘暴天气的PM_(10)和雾霾天气的PM_(2.5)急性染毒导致大鼠白细胞系参数即免疫力显著下降。污染天气颗粒物染毒后大鼠BALF氧化炎症因子的改变表明呼吸系统受到感染:沙尘暴和清洁天的PM_(10)染毒均显著提高了TGF-β1,雾霾PM_(10)染毒后IL-6和LDH有一定程度升高。3种天气颗粒物染毒对肺和气管造成的组织病理伤害各有特点,但PM_(2.5)伤害程度普遍大于PM_(10)。染毒颗粒物粒径大小,其化学成分类别、浓度是造成大鼠血常规指标变化、氧化炎症反应和组织学病变的可能原因。     

The temporal changes of the concentration level of typical toxic organics in the river sediments around Beijing

In this study, the current situation of five types of toxic organics and endocrine disrupters in the sediments of rivers around Beijing, i.e., polycyclic aromatic hydrocarbons (PAHs), phthalic acid esters (PAEs), organic chlorinated pesticides (OCPs), estrogens (Es), and bisphenol A (BPA), which included 56 contaminants, was analyzed and compared with that registered by the historical literatures. The ecological risks were also assessed. The total concentration of PAHs, PAEs, OCPs, Es, and BPA ranged from 232.5 ng·g^–1 to 5429.7 ng·g^–1, 2047.2 ng·g^–1 to 18051.5 ng·g^–1, 4.5 ng·g^–1 to 11.7 ng·g^–1, 18.1 ng·g^–1 to 105.2 ng·g^–1, and 36.3 ng·g^–1 to 69.6 ng·g^–1, respectively. Among these five types of organic compounds, the concentration levels of PAHs and OCPs have decreased significantly in the last ten years, while those of PAEs and Es had an upward trend compared with the previous studies. BPA still remained at a moderately high level, as it was ten years ago. The risks of the PAEs in all of the sample sites, and fluoranthene, benzo[a]anthrene, and benzo[a]pyrene in the Wenyu River sediment, were relatively high. These results supplemented the database of toxic organics’ concentration levels in the sediments of Beijing rivers.

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土石坝管涌溃坝过程数学模型及应用

通过国内外土石坝管涌溃坝模型试验发现,管涌通道断面在溃坝过程中呈现城门洞形,并不断发展扩大直至坝顶发生坍塌。而目前常用的管涌溃坝过程数学模型大多假设管涌通道为圆形或矩形,与实际情况不符。基于土石坝管涌破坏机理,提出一个土石坝管涌溃坝过程数学模型,模型假设初始管涌通道断面为底部正方形顶部半圆形的城门洞形,采用基于水流剪应力的冲蚀公式模拟冲蚀过程管涌通道两侧边向外的发展,采用普罗托季亚科诺夫压力拱理论模拟管涌通道顶拱的发展;通过比较管涌通道上部坝体的重力与管涌通道两侧土体的抗剪强度判断管涌通道的垮塌,分别选择孔流和堰流公式模拟管涌通道坍塌前后的溃口流量;当管涌通道坍塌后,假设坍塌的土体立刻被溃坝水流带走,随后发生漫顶破坏,使用极限平衡法模拟漫顶溃坝过程中的溃口边坡稳定性。模型采用按时间步长迭代的数值计算方法模拟溃口的水土耦合过程,选择国内外25个具有实测资料的土石坝管涌溃坝案例对模型进行验证,比对峰值流量、溃口最终宽度及溃坝历时等参数发现,模型计算结果与实测值的相对误差可满足工程需求,验证了模型的合理性。     

Exploring the administrative mechanism of China's Paired Assistance to Disaster Affected Areas programme

The Paired Assistance to Disaster Affected Areas (PADAA) programme is a mutual aid initiative with Chinese characteristics, which speeded up the process of restoring and reconstructing regions affected by the Wenchuan earthquake on 12 May 2008. 1 The PADAA is an efficient instrument for catastrophe recovery, yet it remains a mysterious mechanism to many members of disaster management communities. This paper aims to lift the veil on it by assessing its origins and evolution. It draws on the multi‐level moderated competition model to explain how the PADAA functions within the Chinese administrative system. The country's top‐down political system allows the central authority to mandate provincial and local governments from more economically developed regions to assist devastated areas with post‐disaster reconstruction. The practices of local accountability complement vertical control by giving leaders from donor regions strong incentives to accomplish assigned reconstruction tasks, resulting in intense competition between them.     

互相关算法在次声监测数据处理中的应用

次声监测数据处理技术是我国履行全面禁止核试验条约必备技术之一。重点介绍逐次多通道互相关(PMCC)算法原理、处理流程以及与之相关的数据处理系统,并利用典型次声事件进行了实验研究。结果表明PMCC在处理次声监测数据方面具有优异性能。