内源性土壤苏云金杆菌(BRC-ZYR2)对含氧铬还原的影响研究

Chromium（Cr） may cause losses in the yield of field plant, which is one of the favorite habitats of Bacillus thuringiensis（Bt）. The purposes of our study were to assess the Cr（VI）-resistance and Cr（VI）-reducing abilities of an indigenous soil isolate of Bt and to determine the factors governing Cr（VI） reduction. Towards this end a novel dichromate-reducing Bt BRC-ZYR2, characterized with insecticidal crystal proteins（ICPs）, was isolated from a uranium deposit. Minimum inhibitory concentrations（MICs） of Cr（VI） were determined by broth dilution method and the concentrations of Cr（VI） and total Cr in the supernatant were quantified colorimetrically using 1,5-diphenylcarbazide（DPC） reagent and a mixture of sulfuric-nitric acids, respectively. The isolate contained five ICP genes（cry1Ba, cry1 Bb, cry1Be/cry1 Bf, cry9 Ca and cry9Da） and exhibited a high level of Cr（VI） resistance with MICs of 150 mg L-1at pH 7.0 and 30？C, and 500 mg L-1under optimal conditions（pH 9.0 and 40？C）. The total Cr concentration was similar to initial concentration of Cr（VI） under the optimal condition, suggesting that the essential removal of the Cr（VI） was dependent on Bt reduction. Under optimal conditions, the initial Cr（VI） concentrations from 25 to 75 mg L-1significantly decreased in 24 h after incubation. Addition of Mn2＋, Co2＋, Mo2＋and Cu2＋activated Bt-mediated Cr（VI） reduction, while Zn2＋, Ni2＋and glucose were found to inhibit the reduction. Our results indicated that this isolate could be a promising biopesticide with the potential for both insect biocontrol and Cr bioremediation in the field.     

陇东和陇中黑垆土的发生与演变

前人认为，我国黑垆土是现代草原环境条件下形成的。我们通过对陇东和陇中黑垆土理化性质分析，１４Ｃ年代和孢粉组成的测定。认为这里的黑垆土是由深色埋藏古土壤层和浅色表土覆盖层叠加构成。剖面呈两段性构造。古土壤层由晚更新世晚期开始发育，主要成壤于全新世中期，具有与现代成土环境不相符合的深厚腐殖质蓄积层，理化性质，孢粉成分等残遗埋藏特性。浅色表土层是全新世晚期气候传向旱型化条件下发育的土壤，其性质和现代成土     

高钙日粮致鸡尿液及尿沉渣变化的研究

100羽伊沙雏蛋鸡饲养至35日龄，随机均分为对照组和高钙日粮组。对照组饲喂全价雏蛋鸡料(含钙1．0％)，高钙组在此基础上添加石粉使实际含钙量达3．85％。对两组鸡均进行结肠造口术，收集尿液，研究鸡尿液及尿沉渣的变化。结果表明，高钙日粮导致严重的肾脏病变和病理组织学损害，造成轻度痛风；病鸡尿量显增加，尿液密度降低，pH值升高；高钙组鸡尿液中尿酸、钙、钾、钠与镁的相对含量均低于对照组，无机磷的相对含量与对照组相似；高钙组鸡24h尿液中尿酸、钙、镁及无机磷的总量显高于对照组，钾和钠的总量低于对照组。扫描电镜下可见高钙组尿沉渣晶体结构发生变化，以针状较多。能谱分析表明，高钙组尿沉渣中钙、磷含量升高，而钾、钠含量均下降。     

南方贮木场原木库存量CAR模型的研究

本文主要论述利用多变量ＣＡＲ模型预报南方贮木场原木库存量动态变化，并用微机模拟．结果表明：该方法模型预报精度高，且应用方便．     

喷洒部件及喷雾助剂对担架式喷雾机在桃园喷雾中的雾滴沉积分布的影响

采用诱惑红为指示剂研究测定了喷洒部件以及喷雾助剂Silwet408对电动担架式喷雾机在桃园喷雾中的雾滴沉积分布的影响,试验结果表明：采用喷枪大容量喷雾,当施药液量为250 L/667 m2时,有35.2%的药液流失到地面,喷雾雾滴在桃树冠层内膛和外膛的上/下层沉积比分别为0.59和0.62;当在喷雾液添加0.1%的Silwet408并把施药液量降低到125 L/667 m2时,药液在地面的流失率减少到21.2%,喷雾雾滴在桃树冠层内膛和外膛的上/下层沉积比分别为1.28和1.19,沉积分布均匀性明显提高。采用装配小喷片的组合喷头喷雾,当施药液量为250 L/667 m2时,有28.4%的药液流失到地面,当在喷雾液添加0.1% 的Silwet408并把施药液量降低到185 L/667m2时,喷雾压力分别为0.25 Mpa和0.35 Mpa时,药液在地面的流失率分别减少到18.5%和8.6%。研究测定结果表明,通过更换喷洒部件、增加喷雾压力、减少施药液量、添加喷雾助剂等措施可以显著减少果园喷雾中的药液流失率、提高喷雾雾滴在桃树冠层的沉积分布均匀性。     

贵州黔西南红土型金矿苔藓植物的调查

为了探明黔西南红土型金矿苔藓植物种类,为进一步利用苔藓植物作为先锋植物研究红土型金矿区植被修复提供较好的材料,采用梅花采样法对黔西南18个红土型金矿苔藓植物进行全面调查、收集、鉴定。结果表明:金矿区共有苔藓植物14科53属124种,其中,苔类植物1科1属2种,藓类植物13科52属122种;金矿区苔藓植物共有12种区系类型,以世界广布种占主体;金矿区苔藓植物丰富度指数、种相似性指数均较低,苔藓植物生活型主要以矮丛集型为主;在18个矿中寻找到5种广泛分布的苔藓植物种类:银叶真藓(Bryum argentenm)、卵蒴丝瓜藓(Pohlia proligera)、纤枝短月藓(Brachymenium exile)和土生对齿藓(Didymodon vinealis)、硬叶小金发藓(Pogonatum neesii)。     

植保无人机低空低容量喷雾在茶园的雾滴沉积分布及对茶小绿叶蝉的防治效果

为研究植保无人机低空低容量喷雾技术在实现茶园农药减量中的作用,通过在茶园喷施20%吡虫啉可湿性粉剂,比较其与传统大容量喷雾技术对茶小绿叶蝉Empoasca flavescens的防治效果。结果表明,使用3种植保无人机喷雾,安装有TEEJET110015#喷头的植保无人机的雾滴沉积密度为24.1～127.4个/cm~2,平均值为75.8个/cm~2,沉积量为0.002～1.15μg/cm~2,均值0.58μg/cm~2;安装有TEEJET11001#喷头的植保无人机的雾滴沉积密度为15.0～80.4个/cm~2,平均值为47.7个/cm~2,沉积量均值为0.01～1.38μg/cm~2,均值0.70μg/cm~2;安装有TEEJET11003#喷头的植保无人机的雾滴沉积密度为9.2～18.2个/cm~2,平均值为13.7个/cm~2;沉积量为0～1.14μg/cm~2,均值0.57μg/cm~2。农药利用率为49.3%～58.2%。使用3种传统器械喷雾,担架式动力喷雾机喷雾得到的沉积量为0.02～0.30μg/cm~2,均值0.16μg/cm~2,背负式手动喷雾器喷雾得到的沉积量为0.01～0.46μg/cm~2,均值0.23μg/cm~2,背负式电动喷雾器喷雾得到的沉积量为0.01～0.65μg/cm~2,均值0.33μg/cm~2。农药利用率为33.7%～39.6%。结果表明,3种植保无人机喷雾的农药沉积量和利用率均高于3种传统的施药器械,但其喷雾的均匀性还有待提高。施药后4 d,植保无人机低空低容量喷雾对茶小绿叶蝉防治效果为85.8%～90.4%,传统大容量喷雾对茶小绿叶蝉防治效果为91.8%～93.2%,两者差异不显著。药后10 d,前者对茶小绿叶蝉防治效果为72.9%～75.6%,后者防治效果为65.8%～71.6%,说明植保无人机低空低容量喷雾对茶小绿叶蝉的防治效果优于传统大容量喷雾。研究结果表明,植保无人机低空低容量喷雾有着更长的持效期,为茶园的农药减施增效提供了可能性。     

Analysis of the microbial communities in soils of different ages following volcanic eruptions

Volcanism is a primary process of land formation.It provides a model for understanding soil-forming processes and the role of pioneer bacteria and/or archaea as early colonizers in those new environments.The objective of this study was to identify the microbial communities involved in soil formation.DNA was extracted from soil samples from the Llaima volcano in Chile at sites destroyed by lava in different centuries(1640,1751,and 1957).Bacterial and archaeal 16 S r RNA genes were analyzed using quantitative polymerase chain reaction(q PCR)and Illumina Mi Seq sequencing.Results showed that microbial diversity increased with soil age,particularly between the 1751 and 1640 soils.For archaeal communities,Thaumarchaeota was detected in similar abundances in all soils,but Euryarchaeota was rare in the older soils.The analysis of bacterial 16 S r RNA genes showed high abundances of Chloroflexi(37%),Planctomycetes(18%),and Verrucomicrobia(10%)in the youngest soil.Proteobacteria and Acidobacteria were highly abundant in the older soils(16%in 1640 and 15%in 1751 for Acidobacteria;38%in 1640 and 27%in 1751 for Proteobacteria).The microbial profiles in the youngest soils were unusual,with a high abundance of bacteria belonging to the order Ktedonobacterales(Chloroflexi)in the 1957 soil(37%)compared with the 1751(18%)and 1640(7%)soils.In this study,we show that there is a gradual establishment of the microbial community in volcanic soils following an eruption and that specific microbial groups can colonize during the early stages of recovery.     

黑土区典型小流域土壤侵蚀空间格局模拟研究

利用校正后的基于GIS的USLE模型预测了黑土区域土壤侵蚀量的空间分布格局。研究结果表明,研究区小流域年侵蚀量值范围在0~60t/(hm² a),无侵蚀、轻度侵蚀、中度侵蚀和强度侵蚀面积分别占研究区总面积的28.7%,56.2%,18.6%和0.1%。研究区坡顶土壤侵蚀量较少〔0~5t/(hm² a)〕,坡肩和坡背侵蚀量较大〔3~15t/(hm² a)〕。基于GIS的USLE不能够很好地模拟黑土区坡麓和坡足区域土壤沉积和侵蚀沟的空间分布格局,但可以较好地模拟坡顶、坡肩和坡背处的土壤流失状况。     

汉江上游阶地黄土磁学特征研究

汉江上游地区位于北亚热带季风气候区边缘,对气候响应异常敏感。流域内发育不对称四级阶地,且阶地上覆盖有厚度不等的黄土堆积。以汉江上游三级阶地黄坪村（HPC）和高客站（GKZ）两个剖面作为研究对象,测量样品的磁化率和频率磁化率,并选取代表性样品进行热磁曲线、等温剩磁获得曲线和磁滞回线等的测定。结果表明,汉江上游黄土沉积物中的载磁矿物以磁铁矿和磁赤铁矿为主,同时含有一定量的赤铁矿和针铁矿,磁化率的增强以超顺磁和准单畴亚铁磁性矿物的贡献为主。GKZ剖面中低矫顽力亚铁磁性矿物含量低于HPC剖面,且黄土中含有更多的亚铁磁性矿物,HPC剖面中则黄土-古土壤中载磁矿物差别不大。汉江上游磁化率的降低与该区较高的有效降水量有关,季节性丰沛降水使土壤水分过饱和,在局部湿润的还原环境中,土壤中大量强磁性铁氧化物被溶解转化为能够在湿润环境中稳定存在的弱磁性矿物,磁性矿物的转化导致成壤强的汉江上游地区磁化率低于成壤弱的黄土高原地区。在成壤条件处于还原环境时,有效降水越高,还原程度也越高,强磁性铁氧化物被溶解得越多,磁化率就越低,这是GKZ剖面降水大于HPC剖面,但磁化率却更低的原因。