基于熵信息扩散理论的中国农业水旱灾害风险评估

农业水旱灾害是制约中国农业生产的重要因素。针对信息扩散理论模型存在的不足,论文构建了评估中国农业水旱灾害风险的熵信息扩散理论模型,依据1985-2013年数据资料,运用熵信息扩散理论模型对中国大陆30个省、市、自治区（重庆包含在四川中计算）的农业水旱灾害进行了风险评估,根据农业水旱灾害风险评估结果对中国农业水旱灾害风险进行了综合对比分析。评估和分析结果表明：中国面临着较大的农业水旱灾害风险压力;中国农业旱灾风险明显大于农业水灾风险;农业水旱灾害空间风险特征明显;农业水灾高中风险区域主要集中在长江中下游地区和东北地区,农业旱灾高风险区域主要集中在中国北部地区和东北地区,总体上看,中国农业水旱灾害的空间分布格局是南方地区易出现水灾,而北部地区易出现旱灾,东北地区面临水旱灾害重叠的双重压力。     

国外节水面面观

美国水资源丰富,但旱灾对农业、能源、运输等造成的危害仍然非常大。旱灾迫使美国人养成了强烈的节水意识。这当中除了政府的管理细致到位外,国民把节水当成一种有教养的表现,并融于社会文化中则是一个更为重要的原因。     

组合赋权法在农业旱灾脆弱性评价区划的应用

德阳市多次发生旱灾,对其经济以及农业生产带来严重的影响。该文从脆弱性角度出发,从敏感性和恢复性2个方面选取指标体系,采用层次分析法和变异系数法相结合的组合赋权法确定权重,采用加权综合评分法构建评价模型,对德阳市以及市辖的6个区(县、市)旱灾脆弱性进行区划。分析表明,该方法具有普遍性、客观性和可靠性,在农业旱灾脆弱性评价中具有广泛应用价值,也为决策者提供了科学依据。     

宋代关中地区旱灾研究

通过对宋代关中平原历史文献资料的整理和分析,来了解此时关中平原干旱灾害的年度变化、等级差异、发生季节、地区间的频次分布情况。据统计,宋代关中平原从公元960年至1279年,共319年,发生旱灾95次,平均每3.3年发生一次;旱灾频次在宋代早、中、晚期变化不均,早期发生频次最多,中期最少,晚期较少,但变幅较大。旱灾主要集中于春、夏两季;空间上关中自东向西灾害频次逐渐增多。在旱灾等级分布上,可划分为小、中、大、特大四级灾害,各占40%、35%、17%、8%。旱灾频发的原因主要有降水和气候异常波动、地形位置、人口增加、政治战争等。     

基于自助法与云模型的区域旱灾风险评估及区划研究

区域旱灾风险评估与区划是科学揭示旱灾风险系统要素相互作用与演变机制的基础性工作,可为制定区域旱灾风险防控措施、实现旱灾风险管理提供合理有效的决策依据。为系统描述区域旱灾风险系统包含的随机性、模糊性及未确知性等复杂不确定性信息,论文基于随机抽样Bootstrap方法在合理构建区域旱灾风险系统样本方案集的基础上,将传统的确定性旱灾等级标准进行云化处理,采用正向正态云算法对区域因旱受灾风险系统Bootstrap样本集进行风险估计,并借助ArcGIS自然间断点分级法对区域旱灾风险分布状况进行区划研究,最终建立了基于自助法与云模型的区域旱灾风险评估及区划模型。该模型在安徽省的应用结果表明：1）云模型方法能较好地描述旱灾风险系统的不确定性,计算所得的旱灾风险率区间估计结果能进一步反映风险内涵;2）淮北平原（阜阳市、宿州市、亳州市、滁州市）、江淮丘陵地区（六安市）及皖东南山区（黄山市、池州市）未来发生旱灾风险事件的总体概率较大,是安徽省旱灾风险管理的重点区域。可见,采用云模型方法进行旱灾风险评估能进一步降低旱灾风险系统不确定性对评估结果的误差影响,对区域旱灾风险评估及区划的理论与实践研究具有参考应用价值。     

旱灾对石漠化影响评估及灾后石漠化防治分区

以西南五省区(四川、重庆、云南、贵州、广西)为研究对象,将岩性、坡度、降水、土地利用、土壤类型、植被覆盖度、与居民点距离、人口密度作为评价指标,研究了石漠化敏感性及西南旱灾导致的变化,并以贵州省兴义市为示范,制定了旱灾后石漠化防治分区. 结果表明:干旱可提高石漠化敏感性,受旱灾程度越深,石漠化敏感性增强越明显. 旱灾导致西南五省区石漠化极重度敏感区和重度敏感区面积分别增加了777和16 484 km2. 贵州省兴义市石漠化敏感性显著变化面积最大,达到石漠化总面积的54%,灾后治理区、监督区、预防区的面积分别为110.9、221.8和509.1 km2,其中需对33.7 km2的石漠化区域进行优先治理.      

民国时期山东蝗灾与灾民应对

蝗灾是近代山东三大自然灾害之一,其危害程度仅次于水灾和旱灾。民国时期,山东蝗灾频发,且往往与旱灾相连,对山东的农业生产造成巨大的损失,以致灾民无数,饿殍塞途。面对蝗虫的侵袭,人们往往会心生恐惧、焦虑,继而采取各种形式的应对措施,如拜神、演戏、捕蝗、典当、逃荒等等,呈现出了蝗虫肆虐之下的灾民群像,同时也体现了人们在禳蝗、灭蝗无果时的无奈与辛酸。     

清代陇东地区旱灾时空特征分析

根据清代历史文献资料中关于陇东地区旱灾的记载,以州县为空间单元,通过对清代该区历史文献中记载的旱灾史料搜集和整理,对该区旱灾发生的时空特征、等级序列进行了初步研究。统计结果分析显示:该区中度旱灾最多,且有明显的季节性、普遍发生和集中发生的特征。该区的静宁县、正宁县为旱灾的频发区。     

民国时期辽宁水旱灾害研究(1912—1948)

民国时期辽宁水旱灾害发生频繁,分析其时空分布对深入了解水旱灾害的概况及有效防灾减灾意义重大。通过对民国时期辽宁水旱灾害史料的统计分析,发现民国时期辽宁水旱灾害频发,几乎年年有灾,甚至许多年份两灾并发;水旱灾害的时间分布呈现不平衡性,主要集中于春夏两季,水灾多发于夏季,旱灾则多发于春季;旱灾的持续时间与水灾相比更具连续性,但水灾的波及地域较旱灾更具广泛性;水旱灾害的地区分布具有明显的区域性,水灾多发于辽中地区,旱灾则多发于辽西地区。     

并不缺水的旱灾——关于我国旱灾的深刻反思

旱不像洪水和地震，一发生便惊天动地、 势不可挡。最痛苦的一个词语最适宜于干旱，那就是“煎熬”。只有身在其中才真正体会到煎熬的滋味。因此，虽然灾区的人民群众在干渴中顽强地生存着，各级地方政府也采取了各种措施积极抗灾、但是２０００年肆虐全国的旱灾却未必引起全社会的重视，或者说忽略了旱灾发生的更深层原因。官方就２０００年旱灾发布的消息中别有深意地说：“专家特别指出，全社会对我国严重缺水的基本国情认识不足。”旧病未愈，又添新伤，2001年又一场严重的旱灾在全国范围内发生，在某些地区旱灾的严重性已经超过了2000年，严重的旱灾甚至使地处长江边上的武汉市区一次又一次地亮起了用水红灯。 经过一些专家学者、新闻记者对近几年来尤其是２０００和２０（）年综合全国各地的旱灾情况发现，多年累积下来的弊病在这场灾害面前暴露元遗。     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.