Btk蛋白在红壤胶体上的吸附解吸行为及其对杀虫活性的影响

研究了苏云金芽胞杆菌库斯塔克亚种（Btk）两种分子量不同的杀虫蛋白（65 kDa和130 kDa）在红壤胶体上的吸附、解吸和杀虫活性。Btk杀虫蛋白容易被红壤胶体吸附,0.5 h即达到吸附平衡,65 kDa蛋白的吸附速率高于130 kDa蛋白。两种Btk杀虫蛋白在0.1 mol L^-1Tris缓冲液（pH 8）中的等温吸附曲线均符合Langmuir方程（R²>0.992）,65 kDa蛋白的吸附量高于130 kDa蛋白。在10～50℃范围内,温度升高吸附量略有降低。pH 6～8范围内,吸附量随pH升高而下降。两种Bt蛋白在红壤胶体吸附前后对棉铃虫均具有杀虫活性,而且吸附后杀虫活性提高了2～5倍。解吸实验表明,Btk杀虫蛋白与红壤胶体结合比较牢固,吸附态65 kDa蛋白和130 kDa蛋白经3次去离子水解吸,总解吸率分别为37.2%和22.9%,经3次pH8的Tris缓冲液解吸,总解吸率分别为20.7%和14.8%。红外光谱分析表明,两种分子量的Bt蛋白在吸附前后结构没有明显变化。透射电镜分析表明,吸附前后红壤胶体颗粒粒径未发生改变。吸附态Bt蛋白杀虫活性提高且不易被解吸,提示转Bt基因作物释放蛋白可能存在环境风险。     

新农药哌虫啶在三种典型土壤中的吸附与淋溶研究

应用振荡平衡法和柱淋洗法研究了哌虫啶在红壤、棕壤和黑土3种典型土壤中的吸附和淋溶特性,并探讨了3种土壤改良剂对其淋溶的影响。结果表明:哌虫啶在黑土、红壤和棕壤中的吸附平衡时间分别为12、12和9 h,分配系数Kd分别为23.16、11.24和4.68,吸附常数Kf分别为22.03、11.69和5.05,KOC值分别为1 619、2 094和495,吸附自由能值分别为-16.96、-17.59和-14.02 k J mol-1,Freundlich和线性等温吸附模型均能较好地描述哌虫啶在土壤中的吸附过程,其吸附能力顺序分别为黑龙江黑土福建红壤山东棕壤。哌虫啶在3种供试土壤中淋溶性存在差异,在棕壤中迁移性最强,随着施药量的增加,其淋出率也略有提高,但3个不同水平施药量差异不显著。在黑土中迁移性最弱,红壤和黑土中的哌虫啶残留量随着土壤深度的增加逐渐降低。土壤中添加0.5%的活性炭、腐殖酸和草炭能显著地降低农药哌虫啶在土壤中的淋溶性,减少对地下水的污染风险。     

鲜带鱼不同贮藏温度的货架期预测模型（简报）

为了研究鲜带鱼在冷链流通中的品质变化与货架期,通过不同温度下的贮藏试验研究了鲜带鱼的货架期预测模型。将鲜带鱼贮藏在268、273、278、283和293 K条件下,测定了鲜带鱼的总菌落数、总挥发性盐基氮（T-VBN）、鲜度指标（K值）与感官品质指标的变化。在Arrhenius动力学方程基础之上,建立了菌落总数、总挥发性盐基氮和鲜度指标（K值）与贮藏时间及贮藏温度之间的动力学模型。试验表明一级化学反应动力学模型和Arrhenius方程对总菌落数、总挥发性盐基氮（T-VBN）及鲜度指标（K值）的变化具有较高的拟合精度。菌落总数变化预测模型中的活化能（EA）及速率常数（k0）分别为：71.26 kJ/mol和3.987×1013,挥发性盐基氮变化的活化能（EA）及速率常数（k0）分别为：68.86 kJ/mol和2.159×1012,鲜度指标（K值）变化的活化能（EA）及速率常数（k0）分别为：41.26 kJ/mol和2.539×107。结果表明,鲜带鱼的总菌落数、总挥发性盐基氮（T-VBN）、鲜度指标（K值）随着贮藏时间的延长而增加,且随着贮藏温度的升高而增加迅速,其感官品质指标随着贮藏时间的延长而下降,且随着贮藏温度的升高而下降迅速。该试验建立的带鱼货架期预测模型所获得货架期预测值准确率达到±10%以内,可根据菌落总数、T-VBN值及K值在268～293 K范围内,对带鱼的剩余货架期进行预测。     

五氯酚在酸性土壤表面的吸附-解吸特征研究

本实验研究五氯酚在江西红壤和南京黄棕壤表面的吸附-解吸特征,结果表明:Freundlich和Langmuir等温吸附方程均能较好地描述PCP在两种土壤表面的吸附,且黄棕壤表面的最大吸附量大于红壤。用动力学方程对PCP在红壤中的吸附过程进行拟合,Elovich方程、双常数方程和一级动力学方程均得到较好的结果,其相关系数(R2)在0.96 ~ 0.99之间,达到极显著水平。Elovich方程反映出PCP在土壤表面吸附的能量非均质分布;而抛物线扩散方程不能描述PCP的吸附过程,其相关系数0.46 ~ 0.48。PCP在土壤中的解吸率与有机质含量和pH值相关,随有机质含量增加,PCP解吸率降低,即黄棕壤表土<黄棕壤底土,红壤表土<红壤底土;随模拟酸雨的pH值降低,土壤因对PCP的吸附能力增加,其解吸率降低。     

壬基酚在土壤中的降解和吸附特性

采用室内模拟试验,研究了壬基酚（NP）在3种土壤中的降解和吸附特性。结果表明,NP在土壤中的降解分为快速和慢速降解阶段,半衰期分别为6.74～9.72d和70.02～78.77d。降解前期3种土壤中的降解速率相差较大,依次为黑龙江黑土〉北京潮土〉广西红壤,与土壤有机质含量相一致,随培养时间推移,降解速率差异减小。NP在土壤中具有不同结合状态及异构体降解性不同可能是出现慢速降解阶段的主要原因。土壤对NP的吸附较为符合Linear等温吸附方程（r≥0.9686）,黑龙江黑土、北京潮土和广西红壤中吸附常数Kd值分别为65.52、31.66和32.71,黑龙江黑土对NP的吸附最强,广西红壤和北京潮土的吸附能力较为接近。各土壤理化性质参数中,以土壤有机质含量对NP吸附的影响最大（r=0.9950）,阳离子交换量对吸附也有一定影响,粘粒含量和pH对吸附的影响较小。NP在3种土壤中的有机碳吸附常数KOC在3696.22～4334.51之间,移动性很弱,吸附自由能变化均小于40kJ·mol-1,NP在土壤中的吸附以物理吸附为主。     

酸性条件下红壤表面Zn^2＋-H^＋反应动力学的能量特征

用自行设计的动力学装置研究了酸性条件下Zn在红壤表面的反应动力学能量特征。结果表明,酸性条件下,Zn吸附分为快反应和慢反应。用一级动力学方程拟合的Zn最大吸附量：pH5.5处理Zn的最大吸附量在289 K时为1.79 mmol.kg^-1,在313 K时为2.62 mmol.kg^-1;pH3.3处理Zn的最大吸附量在289 K时为0.12 mmol.kg^-1,在313 K时为0.16 mmol.kg^-1。即吸附量随酸度增加显著下降,随温度升高明显增加。用扩散速率常数计算的活化能（ΔE＊）：pH5.5处理Zn的ΔE＊为9.05 kJ.mol^-1,pH3.3处理Zn的ΔE＊为12.02 kJ.mol^-1,随酸度的增加ΔE＊增加,Zn扩散需克服的能障加大,Zn吸附量降低。ΔH值为正,温度升高可促进Zn的扩散;ΔS值均为负,说明吸附反应使体系有序度增加。原液pH为5.5时,流出液的pH急剧下降;pH4.3、pH3.8和pH3.3时流出液比流入液的pH高,是由于土壤的缓冲作用和土壤表面质子化;当溶液中H＋超过一定数量后,反应初期的H＋消耗是快反应过程,H＋对矿物的溶蚀成为速率控制步骤。     

钠、钾离子对Bt蛋白在蒙脱石和凹凸棒土表面吸附与解吸的影响

采用静态吸附法研究了钠、钾离子对苏云金杆菌杀虫蛋白在蒙脱石和凹凸棒土表面吸附与解吸特性的影响。结果表明,添加钠、钾离子（0~2 mmol.L-1）均可提高Bt蛋白在两种矿物上的平衡吸附量,但等温吸附曲线的Langmuir方程拟合基本没受影响。添加钠离子或钾离子均能引起矿物粒子Zeta负电位升高,提示钠、钾离子通过减小矿物粒子与Bt蛋白之间斥力的方式促进了Bt蛋白吸附。在蒙脱石吸附Bt蛋白过程中添加钠、钾离子可使Bt蛋白的水解吸率升高,但解吸后的残留量变化不大;在凹凸棒土吸附Bt蛋白过程中添加钠、钾离子可使Bt蛋白的水解吸率减小,且解吸后的残留量增加。     

秸秆生物碳质吸附剂的制备及其吸附性能

为了开辟一条废弃生物质材料利用的新途径,该研究以小麦秸秆为生物质材料,通过中低温区间限氧升温熔融碳化方法制备生物碳质吸附剂,并以铜离子为例,研究吸附剂对废水中重金属的吸附性能。结果表明：在中低温区间（200～500℃）制备的吸附剂产率高、能耗小、制备工艺简单、吸附速率快、达到平衡时间短,最慢的吸附剂（P200）需要3 h达到吸附平衡,最快的吸附剂（P500）仅需0.5 h就达到吸附平衡。30℃时吸附剂P500对铜离子的饱和吸附量为11.19 mg/g。吸附动力学过程符合Lagergren准二级反应动力学模型,吸附等温线符合Langmuir方程,分离因子RL值在0～1之间,为有利吸附。扫描电镜分析显示,随着碳化温度的升高,秸秆的微孔变形程度加剧,增大了表面粗糙程度,孔道效应更易发挥,从而提高吸附性能,为生物质吸附剂的工程应用提供参考。     

暗棕壤吸附铜离子特征及其影响因素研究

应用平衡吸附法,研究了不同pH、离子强度、温度、Cu~(2 )浓度和接触时间条件下,暗棕壤对Cu~(2 )的吸附作用,并利用热力学和动力学方程对实验结果进行了拟合。结果表明:(1)随pH提高,Cu~(2 )的吸附率增加,pH 8时的吸附率约为91%。(2)随体系离子强度增加,Cu~(2 )的吸附量先下降后增加。(3)随溶液中Cu~(2 )浓度增加,Cu~(2 )在暗棕壤上的吸附量也增加,并且在低浓度时增加比较迅速。吸附等温线可用Frendlich,Langmiur和Temkin方程很好的描述,其中又以Langmiur方程拟合程度最好。根据Langmiur方程中平衡常数(k_L)得到的热力学参数指出,反应是自发的、吸热的,但增温却没有改变Cu~(2 )在暗棕壤表面的混乱度。(4)随接触时间延长,暗棕壤对Cu~(2 )的吸附量也增大,具体表现为吸附开始的快速反应阶段和经过一段时间后的慢速反应阶段。双常数能更好地拟合暗棕壤对Cu~(2 )的吸附动力学曲线,根据一级动力学方程的反应速率常数(k_D),计算出了Cu~(2 )吸附的活化能和活化热力学参数,指出温度升高有利于提高反应的速率。     

放射性核素~(95)Zr在土壤中吸附的研究

应用同位素示踪技术研究了95Zr在小粉土、黄红壤、青紫泥和海泥中的吸附 ,并研究了不同比活度95Zr对土壤吸附比的影响 ,测定了吸附等温线。结果表明 ,95Zr进入淹水土壤后迅速被土壤吸附达到吸附平衡。不同土壤有不同的饱和吸附率 ,海泥 >青紫泥 >小粉土 >黄红壤     

Temperature sensitivity of soil organic matter decomposition varies with biochar application and soil type

Biochar application has the potential to improve soil fertility and increase soil carbon stock, especially in tropical regions. Information on the temperature sensitivity of carbon dioxide(CO_2) evolution from biochar-amended soils at very high temperatures, as observed for tropical surface soils, is limited but urgently needed for the development of region-specific biochar management targeted to optimize biochar effects on soil functions. Here, we investigated the temperature sensitivity of soil respiration to the addition of different rates of Miscanthus biochar(0, 6.25, 12.5, and 25 Mg ha~(-1)) in two types of soils with contrasting textures. Biochar-amended soil treatments and their controls were incubated at constant temperatures of 20, 30, and 40℃. Overall, our results show that: i) considering data from all treatments and temperatures, the addition of biochar decreased soil CO_2 emissions when compared to untreated soils;ii) CO_2 emissions from biochar-amended soils had a higher temperature sensitivity than those from biochar-free soils; iii) the temperature sensitivity of soil respiration in sandy soils was higher than that in clay soils; and iv) for clay soils, relative increases in soil CO_2 emissions from biochar-amended soils were higher when the temperature increased from 30 to 40℃, while for sandy soils, the highest temperature responses of soil respiration were observed when increasing the temperature from 20 to 30℃. Together, these findings suggest a significantly reduced potential to increase soil organic carbon stocks when Miscanthus biochar is applied to tropical soils at high surface temperatures, which could be counteracted by the soil-and weather-specific timing of biochar application.     

土壤调节剂对土壤物理性质的改善

Effects of non-ionic polyacrylamide(PAM),anionic polyacrylamide(PHP),cationic polyacrylamide(PCAM),non-ionic polyvinylalcohol(PVA),anionic hydrolyzed polyacrylonitrile(HPAN)and polyethleneoxide(PEO)on the physical properties of three different soil stpes were studied.content of water-stable aggregates larger than 0.25mm increased to varying extents for different soils and soil conditioners,Among the six kinds of condiftioners,non-ionic polyacrylamide(PAM) was the most effective for red soil while polyethyleneoxide(PEO)the least effective for Chao soil,red soil and yellow-brown soil.Water-stable aggregates with the molecular weight of PEO within a certain range.Only evaporation rate of Chao soil decreased after aplication of PAM and HPAN to Chao soil and red soil.     

Effects of endogeic earthworms on soil processes and plant growth in coniferous forest soil

Summary The effects of the endogeic earthworm, Aporrectodea caliginosa tuberculata (Eisen) on decomposition processes in moist coniferous forest soil were studied in the laboratory. The pH preference of this species and its effects on microbial activity, N and P mineralization, and the growth of birch seedlings were determined in separate pot experiments. Homogenized humus from a spruce stand was shown to be too acid for A. c. tuberculata. After liming, the earthworms thrived in the humus and their biomass increased (at pH above 4.8). In later experiments in which the humus was limed, the earthworms positively influenced the biological activity in humus and also increased the rate of N mineralization. A. c. tuberculata increased the growth of birch seedlings, with increases observed in stems, leaves, and roots. Neither NH ₄ ⁺ -N fertilizer nor mechanical mixing with artificial worms affected seedling growth. No plant-growth-affecting compounds (e.g., hormone-like compounds) due to the earthworms were present in the humus. The shoot: root ratio in the birch seedlings was not affected by either the earthworms or the fertilizer. The experiments revealed the impact of earthworm activity on soil processes and plant growth.     

Effect of mycorrhizal inoculation and soil restoration on the growth of Pinus halepensis seedlings in a semiarid soil

An experiment was carried out to evaluate the growth of mycorrhizal Pinus halepensis seedlings planted in a semiarid soil amended with urban refuse in southeast Spain. Three fungal species were used: Pisolithus tinctorius, Rhizopogon roseolus, and Suillus collinitus. After 8 months, inoculated seedlings grown under controlled conditions did not differ significantly from controls with regard to plant height and nutrient assimilation. Other features such as root development and stem dry weight showed that the plants grew better in the absence of mycorrhizal inoculation. The mycorrhizal seedlings and the controls were planted in three experimental plots treated with urban refuse (0, 6, and 12 Kg m^-2). After 1 year of growth under field conditions the results showed that the type of fungus inoculated significantly influenced P. halepensis development. This effect varied with the dose of urban refuse. Plant growth was encouraged by the application of refuse but only at the lowest dose. Under these conditions P. tinctorius was the most effective fungus and R. roseolus yielded poorer plant development. The highest application of urban refuse led to notably worse results and a significant decrease in seedling growth compared to controls. In the control plot (without refuse) S. collinitus was the most effective fungus in plant growth improvement. The smallest application of urban refuse had a positive effect on the assimilation of N, P, and K in seedlings inoculated with P. tinctorius and S. collinitus.     

土壤含水率与土壤碱度对土壤抗剪强度的影响

土壤含水率和土壤碱度是表征土壤物理化学性质的两个重要参数。通过室内三轴不固结不排水试验,研究了土壤含水率和土壤碱度对土壤抗剪强度的影响。试验处理采用5种土壤碱度(土壤可交换钠百分比ESP=0、5、10、20、40)和4种土壤质量含水率(0.05、0.10、0.20以及饱和含水率0.34)水平。试验结果显示,土壤黏聚力随着土壤含水率的增加基本上呈先增大后减小之趋势;当土壤含水率在0.10附近时黏聚力达到其最大值。土壤内摩擦角随着土壤含水率的增加而线性减小。土壤碱度对土壤黏聚力的影响机理较为复杂,其影响效果随土壤含水率的增加而减小;但土壤碱度对土壤内摩擦角的影响较小。土壤碱度对土壤抗剪强度的影响程度明显地小于土壤含水率对其的影响程度。     

A review of visual soil evaluation techniques for soil structure

Soil structure forms a key component of soil quality, and its assessment by semi‐quantitative visual soil evaluation (VSE) techniques can help scientists, advisors and farmers make decisions regarding sampling and soil management. VSE techniques require inexpensive equipment and generate immediate results that correlate well with quantitative measurements of physical and biochemical properties, highlighting their potential utility. We reviewed published VSE techniques and found that soils of certain textures present problems and a lack of research into the influence of soil moisture content on VSE criteria. Generally, profile methods evaluate process interactions at specific locations within a field, exploring both intrinsic aspects and anthropogenic impacts. Spade methods focus on anthropogenic characteristics, providing rapid synopses of soil structure over wider areas. Despite a focus on structural form, some methods include criteria related to stability and resiliency. Further work is needed to improve existing methods regarding texture influences, on‐farm sampling procedures and more holistic assessments of soil structure.     

Earthworm avoidance test for soil assessments

For ecotoxicological assessments of contaminated or remediated soils pointing to the habitat function of soils for biocenoses, standardized tests with earthworms (acute test, reproduction test) are available among others. Tests used for routine applications should be sensitive and indicate impacts on test organisms after short test periods. The usually applied earthworm tests do not satisfactorily fulfil these criteria. Therefore, in the present work, a behavioural test with earthworms (test criterion: avoidance) was investigated in detail using uncontaminated, artificially contaminated and originally contaminated soils. It was demonstrated that the avoidance behaviour is primarily determined by pollutants, and not by chemical-physical soil properties. The sensitivity of the presented test reaches the sensitivity of established tests. For waste sites, a considerably higher sensitivity was determined. An avoidance behaviour of at least 80% of the worms leaving the soil to be assessed is proposed as a criterion for toxicity.     

过量施用磷肥对红壤发育的水稻土化学性质的影响及其与水稻生长的关系

A filed experiment with an early rice-late rice rotation was carried out on a paddy soil derived from red soil in the southern part of Zhejing Province to elucidate the effect of excess P application on some important characteristics of soil properies and its relation to nutrient status and grain yields of rice crops.The experimental results indicated that adequate fertilizer P(15 kg P hm^-2)could increase the content of soil available P at the tillering stage of early rice,the contents of N,P and K in the shoots of early rice at primary growth stages,and the grain yield of early rice by increasing valid ears per hectare and weight per thousand grains,which,was mainly related to the higher contents of reduced,non-reduced and total sugar in the shoot at the heading stage, And early rice supplied with excessive P could not yield more than that applied with adequate, P de to the reduction in the valid grain percentage and weight per thousead grains. In addition,one-time excess P supply at a rate as high as 90 kg P hm^-2 could not improve the soil P fertility in case the soil available P content was lower than the initial(3.74mg kg^-1 soil) after an early rice-late rice rotaion,and made a decline in the grain yield increased by per kilogram fertilzer P.Thus,one-time excess P supply should not be adopted for soils with a large P fixation capacity like the paddy soils derived from red soils.     

Mechanisms of production of soil protease by proteolytic Bacillus subtilis in wetland rice soil

In sterile soil inoculated with proteolytic Bacillus subtilis, the correlation between variations in protease activity and cell numbers was investigated during incubation, and the results were compared with those obtained in different growth media. In sterile soil inoculated with B. subtilis, the extracted soil z-FLase activity (hydrolytic activity towards benzyloxycarbonyl-L-phenylalanyl-L-leucine extracted with 0.1 M phosphate buffer) was correlated with the extracted soil protein content (r=0.95; P<0.01) and the number of vegetative cells (r=0.88, P<0.05), while the extracted soil caseinase activity was well correlated with the number of spores (r=0.82, P<0.05) and not with the number of vegetative cells. Extracellular z-FLase activity in different growth media, inoculated with the proteolytic B. subtilis, was correlated with the extracellular protein concentration (r=0.73, P<0.01) and the number of cells (r=0.73, P<0.01), but extracellular caseinase activity was not correlated with either of these measurements. From these results, we concluded that soil z-FLase production might relate to vegetative growth of the proteolytic B. subtilis and soil caseinase might relate to B. subtilis sporulation.