Hydroxyl radical concentrations measured in ambient air

Diurnal variations in the hydroxyl radical concentration of ambient air were measured for the first time by the technique of laser-induced fluorescence.     

A characterization of the detroit wintertime aerosol

The physical characterization of winter-time aerosol in the Detroit area studied over a 7-week period (January–March, 1983) is presented. Total suspended particle levels (<15 μm) were 56 ± 29 μg m^?3, with 66% of the material in the fine (<2.5 μm) particle fraction. Coarse and fine particle masses were reasonably correlated, indicating that local sources, not long-range transport, influenced winter-time aerosol at the site. Mobile sources were responsible for a marked diurnal variation in the nuclei mode particle count and accounted for about 10% of the submicron aerosol mass. Decreases in submicron aerosol concentrations during precipitation appear to be associated with advection of clean air into the area during frontal passage rather than to precipitation scavenging.     

Solid-state polymerization of EDOT derivatives containing acenaphthenequinoxaline ring

The poly (8, 11-bis (3, 4-ethylenedioxythiophen-2-yl) acenaphtho [1, 2-b] quinoxaline) (PBEAQ), was synthesized by solid-state polymerization using ferric chloride (III) as an oxidant in high yield. The structure of the monomer and polymer was elucidated by FT-IR, UV-vis absorption spectrum and element analysis. PBEAQ has an [η] value of 0.42 dl g^?1 at 25 °C in H₂SO₄ (w=98 %). The electrochemical performance of PBEAQ was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy with three-electrode cell configuration in acidic (1 M H₂SO₄), alkaline (6 M KOH) and organic (0.1 M tetraethylammoniumtetrafluoroborate (TEABF₄) acetonitrile solution) electrolytic solutions and PBEAQ exhibits good performance in acidic medium.     

干旱区土壤螨类群落多样性及其与环境因子的相关性分析

【目的】研究干旱区土壤环境因子对土壤螨类群落多样性的影响,对鄯善县7种不同生境进行土壤螨类群落调查与环境因子测定。【方法】采用改良的Tullgren法分离收集土壤螨类,并用Pearson相关分析和典范对应分析方法对土壤螨类群落多样性特征及其与环境因子之间进行相关分析。【结果】共捕获土壤螨类成体标本26 637只,隶属于4目69科98属。7种不同生境之间土壤螨类群落多样性指标均有极显著差异(P<0.001),其中Shannon-Wiener多样性指数(H)依次为防护林＞葡萄园＞杏园＞苜蓿地＞草地＞耕地＞菜地。CCA分析结果表明,第一主轴和第二主轴分别解释了土壤螨类主要群落总变量的29.7%和17.1%,与环境因子的相关性系数分别为0.926和0.929,前两轴共解释了土壤螨类物种类与环境因素关系的92.9%。蒙特卡罗置换检验显示,10个土壤主要理化性质与第一排序轴(F=4.31,P=0.002)和全部排序轴(F=2.68,P=0.002)均存在极显著的相关性。【结论】鄯善县7种不同生境土壤螨类群落多样性与土壤含水量、有机质、容重及全氮含量呈显著相关(P<0.05),其中土壤含水量、全氮和有机质含量对螨类群落结构和多样性的影响显著。     

基于主成分与灰色关联分析的甜高粱品种综合评价

[目的]利用主成分分析法和灰色关联度分析法,对甜高粱的主要性状进行综合分析,为综合评价及筛选优良甜高粱品种提供科学参考.[方法]选取10项性状指标并运用因子分析法确定其权重系数,以新疆地区29份经过初步筛选的甜高粱品种(系)为材料,利用主成分分析法和灰色关联分析,分别确定综合效益值及品种间加权关联度,分析两套理论确定的秩相关系数显著性,对参试甜高粱品种做出综合评价与筛选.[结果]基于主成分分析法的综合效益值变幅为2.4～-3.61,前五名优势品种(系)为TTL-32(F=2.40),TTL-29(F=2.39),TTL-27(F=2.23),TTL-30(F=1.95),SW1(F=1.55);基于加权法的关联度变幅为0.754 4～0.372 3,前五名优势品种为TTL-32(γ=0.754 4),SW1(γ=0.737 9),TTL-29(γ =0.726 9),TTL-27(γ=0.712 6),TTL-30(y=0.688 1).基于两种评价方法下的29份甜高粱品种(系)排名差异不显著(P＜0.01),其秩相关系数达到0.967,说明所选10项指标对评价甜高粱品种(系)综合品质重要性相当.[结论]杂交选育出的甜高粱新品系TFL-32、TTL-29、TTL-27和TTL-30等排名靠前,茎秆效益和籽粒效益等综合效益值高,极具推广潜质;甜饲1号、绿能3号、九甜杂1号、九甜杂2号、醇甜2号、绿能2号等外引品种和当地近年选育品种新高粱7号和新高粱2号等表现稳定;高粱蔗、苏马克、甜320、本地甜高粱和意大利等本地品种已逐渐退化.     

Composting for the Treatment of Cattle Wastes

? Livestock farming in England and Wales is estimated to produce an annual figure of 200 million tons of animal excreta, half generated by the dairy cattle industry. In the United Kingdom, the structure of the cattle industry has shifted from large numbers of small dairy farms to fewer but larger units. The national average herd size increased from 26 to 42 and finally to 64 animals in 1965, 1975 and 1985, respectively. The latest census revealed that currently there were 2.44 million dairy cows and 9.45 million other cattle and calves in the United Kingdom (total 11.89 million), third place after France (21.50 million) and Germany (19.51 million) in the EEC countries.     

Extinction risk assessment of the world’s seagrass species

Seagrasses, a functional group of marine flowering plants rooted in the world’s coastal oceans, support marine food webs and provide essential habitat for many coastal species, playing a critical role in the equilibrium of coastal ecosystems and human livelihoods. For the first time, the probability of extinction is determined for the world’s seagrass species under the Categories and Criteria of the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. Several studies have indicated that seagrass habitat is declining worldwide. Our focus is to determine the risk of extinction for individual seagrass species, a 4-year process involving seagrass experts internationally, compilation of data on species’ status, populations, and distribution, and review of the biology and ecology of each of the world’s seagrass species. Ten seagrass species are at elevated risk of extinction (14% of all seagrass species), with three species qualifying as Endangered. Seagrass species loss and degradation of seagrass biodiversity will have serious repercussions for marine biodiversity and the human populations that depend upon the resources and ecosystem services that seagrasses provide.     

Formation of periphyton biofilm and subsequent biofouling on different substrates in nutrient enriched brackishwater shrimp ponds

Periphyton grown on substrates is known to improve water quality in aquaculture ponds. Five different substrates, (i) bamboo pipe (ii) plastic sheet (iii) polyvinylchloride (PVC) pipe (iv) fibrous scrubber, and, (v) ceramic tile were evaluated for the formation of biofilm in this experiment. The substrates were suspended 25 cm below the water surface. Each type of substrate was collected fortnightly to analyze the abundance and biomass of different periphytic algae and of the biofouling organism. The study was terminated after 60 days due to severe fouling by polychaete. Results showed that pond water nutrients were high on day 60 with mean total ammonia-N, nitrite-N and soluble reactive phosphorus concentrations of 309.6 ± 8.6 μg L^− 1, 26.0 ± 2.7 μg L^− 1 and 87.2 ± 7.1 μg L^− 1 respectively. During the first two weeks the substrates were colonized by 19 periphytic algae. The most abundant family was Bacillariophyta (8 genera) followed by Chlorophyta (7 genera) and Cyanophyta (4 genera). Periphyton colonization on bamboo pipe showed the highest (p < 0.05) biomass in terms of chlorophyll a amongst all the substrates used. The biomass varied from 179 to 1137 μg m^− 2 with mean values of 1137.2 ± 0.6, 929.6 ± 0.6, 684.2 ± 1.2, 179.1 ± 0.6 and 657.0 ± 0.6 μg m^− 2 on bamboo pipe, PVC pipe, plastic sheet, fibrous scrubber and ceramic tile respectively for the first 15 days. From 3rd week, polychaetes began to form tubes on the substrate. By day 60, the whole surface of all substrates was covered with tightly packed polychaete tubes with mean densities of 168.0 ± 15.4, 121.0 ± 13.5, 72.8 ± 9.8, 72.4 ± 7.4 and 56.0 ± 6.8 polychaete tubes cm^− 2 for bamboo, PVC, plastic, fibrous scrubber and ceramic tile respectively. This study illustrated the invasive nature of attached polychaete thus hampering the formation of periphyton biofilm on substrates which could have been used for improving water quality in enriched brackishwater shrimp ponds.     

新疆农产品贸易优势比较分析

在加入WTO后,我国农业将更多的参与国际分工和贸易,逐步走向农业国际化.如何利用地区资源条件,发挥新疆农产品的比较优势,降低生产成本,提高农产品的竞争优势是亟待解决的问题.以比较优势理论为基础,说明在国际经济一体化的大趋势下,各地区应该根据自然资源和要素禀赋的不同,按比较优势的原则合理调整农业生产结构和农村经济结构,参与国内国际分工与国内国际贸易.从新疆农业发展的实际出发,通过定性和定量分析的研究方法,运用价格比较法、国内资源成本法和结构比较优势法对新疆的小麦、玉米、棉花、甜菜、番茄、林果园艺等主要农产品进行多角度的比较优势分析.结合分析结果得出新疆农产品发展的对策和建议.     

吐鲁番火焰山南麓农田生态区土壤螨类群落多样性

【目的】研究火焰山南麓农业生态系统不同土地利用类型生境对土壤螨类群落多样性的影响,为农业生态系统土壤生物多样性保护提供科学依据。【方法】采用野外采样和改良的Tullgren法对吐鲁番火焰山南麓农业生态系统10种土地利用类型生境土壤螨类群落多样性特征进行比较分析。【结果】共采集土壤螨类 21 195头标本,隶属于4亚目68科100属,其中长单翼甲螨属Protoribates为优势类群,Berniniella Balogh,1983和Monogalumnella Mahunka,1986为中国新纪录属。不同土地利用类型生境土壤螨类个体数、类群数及多样性指标之间均有显著差异( P<0.05),其中葡萄园多样性最高,而荒漠最低;群落多样性存在季节差异,秋季最高,而夏季最低少。捕食性螨类以K选择型为主,甲螨主要为O型和P型。【结论】不同土地利用类型螨类群落多样性指标之间存在显著差异,地表凋落物和人为干扰是影响该区土壤螨类群落多样性的主要因素。