碱性土壤基因组DNA的分离纯化和基因文库的构建

直接从广西南宁市凤凰纸业排污沟碱性土壤样品中抽提和分离纯化混合基因组DNA，所获得DNA的产量为每克土壤样品10～30pg。采用限制性内切酶EcoR1酶处理后，构建了以pGEM-3Zf( )为载体的DNA部分文库。文库的容量为23650个转化子。外源片段DNA平均大小为3．2kb。建库效率为每克环境样品获得6000个左右的含1～15kb外源随机插入片段的克隆。通过DNA序列测定和同源性比较，对从文库随机词取的16个转化子序列进行分析，发现13个外源插入片段包含序列尚未确定的DNA片段。     

Solubility of heavy metals in a contaminated soil: Effects of redox potential and pH

To assess the mobilities of Pb, Cd, and Zn from a contaminated soil, the effects of redox potential and pH value on metal solubilities were investigated. Both redox potential and pH were found to greatly affect heavy metal solubility in the soil. Results showed that the soil suspension under continuous oxygen aeration for 21 days resulted in increases of redox potential from 290 to 440 mV and pH value from 6.9 to 7.0, respectively. Soluble concentrations of Pb, Cd, and Zn varied with time, and were all lower than 1 mg kg^?1. When the soil suspension was aerated with nitrogen, final redox potential was ?140 mV and pH value of 7.1. The soluble metal concentrations were slightly higher than those aerated with oxygen. The equilibrium solubility experiments were conducted under three different pH values (3.3, 5.0, 8.0) and three redox potential (325, 0, ?100 mV). Results showed that metals were sparingly soluble under alkaline conditions (pH = 8.0). Metal solubilities were higher when under slightly acidic conditions (pH = 5.0), and increased drastically when pH was kept at 3.3. When solubilities were compared under same pH values, it was observed that metal solubilities increased as redox potential decreased. Generally speaking, acidic and reducing conditions were most favorable for metal solubilization, and the effect of pH was more significant than that of redox potential. It was proposed that heavy metals were mostly adsorbed onto Fe-Mn oxyhydroxides. The pH-dependent metal adsorption reaction and the dissolution of Fe-Mn oxyhydroxides under reducing conditions was the mechanism controlling the release of heavy metals from soils.     

不同氮素形态及比例对烤烟长势、产量及部分品质因素的影响

在湖南浏阳,运用田间小区试验研究了硝态氮、铵态氮比例(RN)对烤烟田间长势与产量以及部分品质因素的影响。结果表明:1)RN对烤烟的农艺性状、产量、产值、均价等没有明显影响,而对烤烟的等级结构、内在化学成分含量、氮、钾、氯的吸收量有着显著影响,可以用显著的二次多项式模型或直线相关方程描述产值、均价、上等烟产量、下等烟产量等经济性状以及烟碱、总氮、钾、还原糖、氯、淀粉、挥发碱等内在化学成分的含量与铵态氮份额之间的关系;2)RN为75%∶25%时,中上等烟比例、烟碱、总氮、钾、钾氯比、氮吸收量最高,挥发碱含量最低。RN为25%∶75%时,挥发碱含量最高,总氮、淀粉含量最低。100%铵态氮时,还原糖、氯含量、淀粉的含量最高,碱、钾、钾氯比最低,同时显著地降低烤烟的等级结构。100%硝态氮时,总氮、钾、氯在烟叶中的含量最低,吸收总量也最少,同时产量、产值、均价也处于最低水平;3)本试验的任何RN下,烟碱、总氮、钾、氯、淀粉的含量均符合优质烟叶要求,而还原糖相反。综合考虑经济效益、养分利用率和烟叶内在化学成分的协调性,整体上RN为54%∶46%～50%∶50%较好。     

Chemical stratification in the Seneca/Oswego rivers (NY)

The occurrence and characteristics of chemically-based density stratification in portions of the Seneca and Oswego Rivers, downstream of ion-polluted Onondaga Lake, are described for seven different days in the summer and fall of 1978 and 1981, which covered a wide range of river flows. The results indicate that chemically-based density stratification occurs routinely in the Seneca River downstream of the lake inflow, in response to a continuous chemically-based density difference between the two systems of 0.0015 to 0.0030 g cm^?3. The persistence of the phenomenon, and therefore the longitudinal range over which the river stratification occurred, was dependent on the velocity of river flow and the magnitude of the density gradient that bordered the upper river water and the lower released lake water. During the low flows common to summer the stratification extended approximately 14 km downstream to a dam, and 3 km upstream, of the lake outlet — river junction. Vertical mixing between the stratified layers increased as the flow in the Seneca River increased, and as the vertical density gradient decreased. A dimensionless group, $$\frac{D}{{V\left( {\frac{\rho }{{\Delta _\rho /\Delta _z }}} \right)}}$$ where: D = apparent vertical diffusion (m² hr^?1), V = average velocity of the overlying river flow (m hr^?1 ), p = density at the interface between the stratified layers (g cm^?3), and Ap/Az = density gradient between the stratified layers (g cm^?3 m^?1), was found to be constant for summer low flow conditions for a 6.5 km length of the Seneca River, thus quantifying the interaction between vertical mixing and the included influences for that portion of the river. The occurrence of chemical stratification in the river had dramatic implications on the corresponding distribution of dissolved oxygen (DO). The isolation of the organically enriched lake water in the lower layer enhanced the depletion of DO there, which resulted in the development of substantial (> 4.0 mg 1^?1 ) DO stratification downstream of the discharge from the lake during summer low flow periods.     

秸秆腐熟剂对茶陵县稻草还田效果的影响

为在茶陵县顺利推广应用秸秆腐熟剂,以"九业"、"豫园"、"湘润邦"3种秸秆腐熟剂为添加材料,2014年在茶陵县进行了稻草还田应用秸秆腐熟剂种植晚稻的小区试验。结果表明,稻草还田应用秸秆腐熟剂能有效地加速稻草腐熟速率,并能改善土壤理化性状,提高土壤有机质含量,降低土壤容重,增加土壤通透性,提高土壤保肥保水和供肥能力,最终提高水稻产量。晚稻实行稻草还田比不实行稻草还田增产4.6%;在稻草还田基础上应用秸秆腐熟剂比单独稻草还田不用秸秆腐熟剂增产6.0%;3种秸秆腐熟剂间的效果没有明显差异,都适宜在茶陵县推广使用。     

人工生物质结皮对黄土边坡微生态环境及植被恢复的影响

针对黄土干旱阳坡植被恢复问题,以山西省方山县黄土弃土边坡为研究地,在2012年4月26日和7月20日分别布设人工生物质结皮进行试验,并于11月30日结束全部试验。通过2次试验研究人工生物质结皮在黄土边坡植被恢复过程中对土壤微生态环境的改善及对植被生长的影响。结果表明:1)人工生物质结皮可提高浅层土壤温度,最高达1.9℃;2)人工生物质结皮可增加土壤含水量,10 cm土层土壤含水量比对照区高35.8%;3)人工生物质结皮对边坡侵蚀具有防护作用,结皮区降雨形成的水蚀细沟体积小于对照区的1/2;4)氮源肥料和碳源生物高分子同时施用时边坡植物生物量超过二者单独使用时的4倍;5)人工生物质结皮可促进土壤种子库植物的萌发,其中土壤种子库植物占结皮区植物生物量的83.06%;6)人工生物质结皮区植被盖度超过90%,远高于裸露黄土对照区和自然坡面的30%和35%的覆盖率,植物鲜质量生物量达1.65 t/hm2,分别为自然坡面和对照区生物量的10.50和20.48倍;7)利用人工生物质结皮可以在一个生长季内在黄土边坡形成高盖度植被,这种方法适用于水土流失严重的黄土丘陵沟壑区的边坡植被快速恢复。     

二氧化硅整体柱的制备及其结构表征

以甲醛、尿素为主要原料合成了脲醛树脂整体柱,并以之为模板,制备二氧化硅整体柱。采用扫描电镜、元素分析仪、氮吸附仪及X-射线粉末衍射仪等手段对所合成材料的内部结构和性能进行了表征。结果表明,脲醛树脂整体柱制备过程中,通过向反应体系中加入聚乙二醇6 000诱导体系发生相分离,得到的脲醛树脂整体柱具有彼此交联的基质骨架和相互连通的穿透孔,以之为模板合成的二氧化硅整体柱也呈现双连续结构。     

樱桃主要病害及其防治措施探讨

樱桃(Cerasus Mill.)在湖北省内多地普遍种植,近年来发展成为一种新兴的种植产业,随着果园规模的扩大,樱桃上的病害不容忽视,通过对湖北省内樱桃上病害的调查,分析了为害樱桃叶部、枝干、根部、果实的主要病害的为害特性,并提出了切实可行的防治措施。     

贵州不同区域水稻各生育期稻田寄生蜂的多样性差异

为探明贵州省不同生态环境水稻3个主要生育期稻田寄生蜂物种组成的异同及多样性特点,采用田间调查的方法在具有不同代表性的4个区域(贵州省榕江县车江乡、绥阳县洋川镇、贵阳市花溪区石板镇和六枝特区平寨镇)进行了调查研究。结果表明:采集到水稻寄生蜂标本5 222号,隶属23科123属224种;各地稻田寄生蜂个体数和丰富度的最高时期出现在乳熟期,除榕江县车江乡稻田寄生蜂的优势度最高时期出现在乳熟期外,其余各地的多样性指数、优势度和均匀度的最高时期均出现在抽穗期-开花期。稻田寄生蜂的多样性取决于其物种数及物种个体数的分布情况。     

贵州枇杷有害生物种类及防治用药调查

为了解贵州枇杷有害生物种类及防治用药,于2012-2014年对贵州省余庆县、施秉县、开阳县和荔波县枇杷有害生物种类及防治用药进行调查。结果表明:贵州省枇杷园发生病害种类共20种,侵染性病害14种,非侵染性病害5种,低等寄生植物1种;害虫种类6目21科35种,同翅目4科12种,鞘翅目4科7种,半翅目3科3种,鳞翅目8科10种,双翅目2科2种,害螨1科4种;杂草28科102种。防治用药共49种,杀虫剂有18种,杀菌剂22种,除草剂9种。