湖南烟区烤烟锌含量与土壤有效锌的分布特点及关系分析

采用野外调查和室内分析相结合的方法,研究了湖南烟区烤烟锌含量与土壤有效锌含量的分布特点及关系。结果表明,(1)湖南烟叶锌含量总体适宜,平均为(36.30±14.05)mg·kg-1,变幅为10.50~100.50mg·kg-1;调查区域内有92.58%的烟叶样本锌含量落在20.00~80.00mg·kg-1区间内;不同等级烟叶锌含量的规律是:B2F>C3F>X2F。(2)湖南植烟土壤有效锌含量适中,平均为(2.27±3.74)mg·kg-1,变幅为0.13~62.59mg·kg-1,变异系数高达155.09%;有22.41%的土壤样本在不同程度上缺锌(≤1.00mg·kg-1),有7.36%的样本的有效锌含量超过4.00mg·kg-1,满足优质烟生长的土壤样本达到70.23%;不同土壤类型有效锌含量的变化规律是:鸭屎泥>黄泥田>黄灰土>黄壤土。(3)烟叶锌含量与土壤有效锌含量呈极显著正相关,相关系数为0.312;与土壤有效铜、有效铁和有效硫均呈极显著正相关,与土壤pH值、有效钾和水溶性氯均呈显著负相关。(4)在土壤有效锌含量分组后,不同等级烟叶锌含量均随着土壤有效锌含量的增加,而呈现先增加后下降的趋势,且各等级烟叶锌含量在组间差异达到5%的显著水平。     

Organic matter and concentrated nitrogen removal by shortcut nitrification and denitrification from mature municipal landfill leachate

An UASB＋Anoxic/Oxic （A/O） system was introduced to treat a mature landfill leachate with low carbon-to-nitrogen ratio and high ammonia concentration. To make the best use of the biodegradable COD in the leaehate, the denitrifieation of NOx^--N in the reeireulation effluent from the elarifier was carried out in the UASB. The results showed that most biodegradable organic matters were removed by the denitrifieation in the UASB. The NH4^＋-N loading rate （ALR） of A/O reactor and operational temperature was 0.28- 0.60 kg NH4^＋-N/（m^3-d） and 17-29℃ during experimental period, respectively. The short-cut nitrification with nitrite accumulation efficiency of 90%-99% was stabilized during the whole experiment. The NH4^＋-N removal efficiency varied between 90% and 100%. When ALR was less than 0.45 kg NH4^＋-N/（m^3.d）, the NH4^＋-N removal efficiency was more than 98%. With the influent NH4^＋-N of 1200-1800 mg/L, the effluent NH4^＋-N was less than 15 mg/L. The shortcut nitrification and denitrifieation can save 40% carbon source, with a highly efficient denitrifieation taking place in the UASB. When the ratio of the feed COD to feed NH4^＋-N was only 2-3, the total inorganic nitrogen （TIN） removal efficiency attained 67%-80%. Besides, the sludge samples from A/O reactor were analyzed using FISH. The FISH analysis revealed that ammonia oxidation bacteria （AOB） accounted for 4% of the total eubaeterial population, whereas nitrite oxidation bacteria （NOB） accounted only for 0.2% of the total eubaeterial population.     

Fenton法处理类长填龄渗滤液的氧化和絮凝作用

采用Fenton法对难降解的类长填龄渗滤液进行处理,考察其氧化和絮凝作用对有机物去除的贡献. 结果表明:以COD_Cr去除率最大为目标,试验在最优条件下,c(H₂O2)/c(Fe2+)为7.0,Fe2+投加量(c(Fe2+))为60　mmol/L,pH为3.0,此时COD_Cr总去除率为60%;其中氧化作用去除率为44%,氧化和絮凝作用的效率比为2.7. c(H₂O₂)/c(Fe2+),c(Fe2+)和pH的变化对氧化和絮凝作用有明显影响,氧化作用对COD_Cr去除率随H₂O₂投加量增大而增大.絮凝作用对COD_Cr的去除率不仅受Fe2+投加量直接影响,随其增加而增大;还间接受氧化作用去除率影响,氧化作用去除率越大,剩余有机物大分子所占比例降低,絮凝作用对有机物的去除率越低.      

郑州市土壤与绿色植物中汞的分布特征

汞污染具有生物积累性,因而得到社会广泛关注。研究监测和评估了郑州市城区土壤和绿色植物叶片中汞浓度、分布、污染水平等。研究发现郑州市主城区土壤总汞浓度为0. 150～0. 958 mg/kg,平均浓度为0. 448 mg/kg;郑州市主城区绿色植物叶片总汞浓度为0. 017～0. 249 mg/kg,平均浓度为0. 107 mg/kg;土壤和叶片中汞浓度按功能区排序为交通枢纽区工业区商业区行政区高教区住宅区。采用地累积指数法对郑州市80个土壤样品的汞污染水平进行评估,结果显示60%受到轻度污染,35%受到偏中度污染,5%受到中度污染。研究较为全面地分析了土壤汞污染的现状及浓度,为郑州市土壤汞污染防治提供参考。     

叶面施硅对水稻籽实重金属积累的抑制效应

采用盆栽方法,以硅酸钠和正硅酸乙酯为硅源分别配制纳米硅制剂,以水稻(Oryza sativa L.)品种"优优128"为供试植物,在Cd(5mg·kg-1、10mg·kg-1、50mg·kg-1三个水平)、Pb(200mg·kg-1)、Cu(250mg·kg-1)、Zn(300mg·kg-1)复合污染土壤进行种植,在水稻生长期内(苗期、分蘖期、抽穗期)进行叶面喷施纳米硅,研究纳米硅对水稻籽实生长状况及吸收重金属元素的影响,并对两种不同硅源的纳米硅的使用效果进行了比较。结果表明,随Cd污染质量分数增加,水稻百粒质量及单株穗质量均显著降低(P<0.01);Cd、Pb、Zn在籽实中质量分数均增高,而Cu在籽实中质量分数降低。金属元素在籽实中的吸收系数顺序为Cd>Zn>Cu>Pb,表明Cd极易向籽实中迁移。随土壤Cd质量分数增加,水稻籽实中各金属元素的积累量都有所降低。重金属复合污染条件下,叶面施用两种硅制剂均可以缓解水稻的毒害效应,且和施无机硅相比,施有机硅对水稻重金属毒害的缓解效果更显著。表现为叶面施用硅后,水稻百粒质量及单株穗质量均显著提高(P<0.05);且籽实中Cd、Pb、Cu、Zn的吸收量在喷施硅制剂后均显著降低(P<0.05);籽实中重金属元素的吸收系数和积累量均表现出降低的趋势。尤其是随着Cd处理质量分数的增高,施硅对重金属在籽实中积累的抑制效应越显著。这表明叶面施硅在重金属污染的水稻田污染防治中具有应用价值。文章所用的纳米硅制剂,制备简单,对于大面积推广硅肥极为有利。     

春蚕期桑叶氟化物含量变化规律分析与研究

春蚕桑叶氟化物中毒引起政府部门的高度重视。通过对历年来桑叶含氟量监测数据统计分析，找出春蚕期桑叶含氟量日均值变化规律，并对规律成因进行探讨研究，为春蚕防氟工作提供科学依据。     

Sensitivity analyses of woody species exposed to air pollution based on ecophysiological measurements

GOAL, SCOPE AND BACKGROUND: Air pollution has been of a major problem in the Pearl River Delta of south China, particularly during the last two decades. Emissions of air pollutants from industries have already led to damages in natural communities and environments in a wide range of the Delta area. Leaf parameters such as chlorophyll fluorescence, leaf area (LA), dry weight (DW) and leaf mass per area (LMA) had once been used as specific indexes of environmental stress. This study aims to determine in situ if the daily variation of chlorophyll fluorescence and other ecophysiological parameters in five seedlings of three woody species, Ilex rotunda, Ficus microcarpa and Machilus chinensis, could be used alone or in combination with other measurements for sensitivity indexes to make diagnoses under air pollution stress and, hence, to choose the correct tree species for urban afforestation in the Delta area. METHODS: Five seedlings of each species were transplanted in pot containers after their acclimation under shadowing conditions. Chlorophyll fluorescence measurements were made in situ by a portable fluorometer (OS-30, Opti-sciences, U.S.A). Ten random samples of leaves were picked from each species for LA measurements by area-meter (CI-203, CID, Inc., U.S.A). DW was determined after the leaf samples were dried to a constant weight at 65 degrees C. LMA was calculated as the ratio of DW/LA. Leaf N content was analyzed according to the Kjeldhal method, and the extraction of pigments was carried out according Lin et al. RESULTS AND DISCUSSION: The daily mean Fv/Fm (Fv is the variable fluorescence and Fm is the maximum fluorescence) analysis showed that Ilex rotunda and Ficus microcarpa were more highly resistant to pollution stress, followed by Machilus chinensis, implying that the efficiency of photosystem II in I. rotunda was less affected by air pollutants than the other two species. Little difference in daily change of Fv/Fm in I. rotunda between the polluted and the clean site was also observed. However, a relatively large variation of Fv/Fm appeared in the other two species, particularly in M. chinensis, suggesting that they were more sensitive to air pollutants than I. rotunda. The mean LA was reduced for all species growing at the polluted site. The mean LMA for all species exceeded the sclerophylly threshold given by Cowling and Campbell and increased for those under pollution stress, which could be explained as one of the acclimation strategies for plants to air pollution stress. Little difference in leaf chlorophyll content was observed in F. microcarpa and M. chinensis, while remarkable differences were found in I. rotunda growing at the polluted and the clean site. Content of leaf carotenoids was largely reduced in I. rotunda growing at the polluted site, but increased in F. microcarpa and M. chinensis, compared with plants growing at the clean site. Plants growing at the clean site had a lower leaf N content than those growing at the polluted site. In addition, species with a higher resistance to pollution stress showed less difference in leaf N content than those sensitive species. CONCLUSION: Based on Fv/Fm measurements of the three woody species, I. rotunda showed the highest resistance to air pollutants from ceramic industries, followed by F. microcarpa. M. chinensis was the most sensitive species to air pollution, had lowest capacities to cope with the air pollution stress, which was consistent with visual injury symptoms observed in the crown profiles of plants at the polluted site. Fv/Fm, LAM, LA, leaf pigments and N content could be used alone or in combination to diagnose the extent of the physiological injury. The ratio of Fv/Fm, however, was the best and most effective parameter. RECOMMENDATION AND OUTLOOK: Tree species which have higher air-pollutant resistance, as diagnosed by such ecophysiological parameters, should be considered first and planted widely for urban afforestation or forest regeneration in areas where the forest was seriously degraded or forest health was markedly effected by the same kind of air pollutants.     

交通污染区城市绿化植物硫含量分布

为探讨城市绿化植物对交通环境中SO2的响应，以远离城市道路的相对清洁区公园生长的植物为对照植物，采集了广东省被广泛栽种的18种园林绿化植物的不同方位的叶片和树皮样品，用硫酸钡比浊法测定了每种植物样品在交通污染区面向机动车行驶方向、面向人行道方向及相对清洁区的植物样品等不同方位的植物叶片和树皮硫含量，分析了绿化植物在同一株植物的不同生长部位和不同环境中硫含量的分布特征。结果表明，交通污染区所有样品的叶片硫和树皮硫含量均高于相对清洁区的样品。其中，远离工厂的交通污染区生长的同一株植物，离机动车道越近，硫含量越高；靠近工厂的交通污染区的同一植物，离工厂近的部位的植物树皮硫含量高于面向机动车道一侧的植物硫含量。     

Oviposition by butterflies on young leaves: Investigation of leaf volatiles

Summary Various butterflies select young foliage on which to lay their eggs; volatiles emitted by young and old leaves have been compared (by sorption enrichment, followed by GC-MS) to gauge possible qualitative and quantitative differences between the two age groups. The plants investigated are cabbage (Brassica oleracea), two milkweeds (Asclepias syriaca andA. curassavica), the bitter orange (Citrus aurantium) and the lime (C. aurantiifolia). The chemical compounds identified belong to three classes, isoprenoids, fatty acid derivatives and benzenoids. Quantitative differences were found between young and old leaves, of which a few may be characteristic of young leaves only. Thirty-four single trials withDanaus plexippus exposed to volatiles from young and old leaves are recorded.     

Induced alkaloid defence inAtropa acuminata in response to mechanical and herbivore leaf damage

Summary Measurement of tropane alkaloid content in leaves ofAtropa acuminata after mechanical damage showed a maximum increase to 153% of the control 8 days later. There were no changes in the root or stem after similar damage. The plant responded to repeated mechanical damage by doubling its alkaloid content at 11 days after the initial wounding. But on further treatments, there was a slight decrease in alkaloid content with time. Mollusc feeding produced an increase of 164% in alkaloid content after 4 days. These results indicate that induced defence systems in angiosperms can vary considerably from plant species to plant species and that the effects of mechanical damage may differ in different parts of the same plant.