水处理絮凝剂研究与应用进展

水处理絮凝剂的发展经历了从最初的传统絮凝剂,到无机高分子絮凝剂,再到有机高分子絮凝剂;从简单的天然有机高分子絮凝剂,到合成的有机高分子絮凝剂,再到基于生态安全性的天然改性有机高分子絮凝剂;从单纯的无机或有机高分子絮凝剂,到有机 无机复合絮凝剂;从化学絮凝剂,再到具有生态安全性能的生物絮凝剂.为了促进水处理絮凝剂的迅速发展和实际应用,本文综述了水处理絮凝剂在国内外的研究进展与应用现状,重点对化学和微生物两大类絮凝剂分别阐述了其特点以及在水处理中的应用情况,并对其发展方向进行了分析和评价;尤其是针对目前我国絮凝剂研究与开发应用中的不足,对今后的研究工作提出了一些建议和设想.     

烤烟缓/控释钾肥研究进展

发展烤烟缓/控释钾肥对于保护生态环境及降低农业生产成本具有重要的意义。总结了国内外有关缓/控释钾肥在烤烟上的相关研究和应用进展,介绍了缓/控释钾肥的基本概念,就缓/控释钾肥对烤烟生长发育、烟叶钾含量及品质性状、经济性状、土壤钾含量的影响作了综述,并且提出了当前研究中的一些问题。缓/控释钾肥能够促进烤烟的生长,提高土壤钾含量,进而提高烟叶钾含量,改善烟叶品质,增加产量产值,但也存在控释钾肥包膜材料和机理研究不足、与普通肥配施研究较少等问题,因此有必要就缓/控释钾肥在国内外的发展现状、前景、存在问题及对策予以讨论,以期为我国缓/控释钾肥产业化提供理论依据。     

抗菌生物材料的研究进展

生物高分子材料(医用缝合线、导尿管等)及人工器官(心瓣膜、人工肾等)的应用日益广泛,使用过程中引发的细菌性感染导致诸多严重后果,不容忽视。基于感染机理,人们通过对生物材料表面进行不同的改性,如通过阻止细菌黏附达到抗菌效果、通过干扰细菌细胞的组成取得杀菌效果等,研究了不同的抗菌机理。本综述了新型有机高分子抗菌剂的发展,提出对生物相容性良好的聚氨酯、聚砜、聚醚砜等材料进行表面改性,使之具有好的抗菌能力,是未来抗菌生物材料的研究与发展方向。     

施用缓/控释尿素对玉米苗期土壤生物学活性的影响

采用盆栽试验,模拟田间生态环境,研究了施用不同种缓/控释氮素底肥对玉米苗期土壤硝酸还原酶、脲酶活性及微生物量碳、氮的影响.结果表明,施用硝化抑制剂(双氰胺)和脲酶抑制剂(n-丁基硫代磷酰三胺)涂层大颗粒尿素肥料的土壤硝酸还原酶活性最高;施用大颗粒尿素,脲酶活性最强,微生物量碳、氮最高.施用醋酸酯淀粉包膜大颗粒尿素、包膜双氰胺涂层大颗粒尿素、丙烯酸树脂包膜双氰胺涂层大颗粒尿素与不施氮肥土壤脲酶活性较高;每种处理微生物量碳与氮变化完全一致.施用醋酸酯淀粉包膜硝化和脲酶抑制剂涂层大颗粒尿素肥料,土壤微生物量碳、氮最低.同种膜材料包膜抑制剂涂层大颗粒尿素制成的缓/控释氮肥,对土壤生物学活性的影响效果好于直接包膜大颗粒尿素;丙烯酸树脂包膜大颗粒尿素制成的缓/控释氮肥,对氮素的控释效果明显好于醋酸酯淀粉包膜.     

有机-无机复合材料胶结包膜肥料的研制及评价

应用水基成膜法制备4种有机-无机复合胶结包膜材料,利用圆盘造粒机制备其胶结包膜肥料(B2、PS、F2、F2F),并对其性质进行了测定.性能测试结果表明：胶结包膜肥料成粒率、抗压强度和成膜性由好至差均为B2＞PS＞F2＞F2F.土柱淋洗试验结果表明：B2氮素累积溶出曲线最平缓;48 d内氮素累积溶出率表现为：54.65%(B2)<56.16%(PS)<59.47%(F2)<63.12%(F2F).玉米田间试验结果表明：与等量NPK化肥配施处理相比,4种有机-无机复合材料胶结包膜肥料处理的玉米产量均有所提高,其中B2处理的增产效果最显著(P<0.05),其玉米产量和肥料利用率分别提高了19.72%和20.30%,F2F处理差异不显著,PS和F2处理效果居中且前者好于后者.     

控释氮钾肥对海棠氮、磷、钾利用率的影响

采用盆栽试验,研究了控释氮钾肥对海棠实生苗生长、磷钾利用率及土壤-作物系统中氮素平衡的影响.结果表明:控释肥的释放与海棠苗对养分的需求一致;控释氮肥显著提高了植株钾素的利用率;控释钾肥显著提高了植株氮素的利用率.施钾量相同情况下,控释氮肥(CN)和控释氮钾肥(NK)的株高、茎粗无显著差异,但均高于普通肥料(SF).植株干物质量、磷的利用率、钾的吸收量和利用率大小顺序均为:NKCNSF.施钾量对株高、茎粗无明显影响,但对NK处理的干物质量有显著影响.磷素利用率随控释钾肥施用量增加而显著提高,而普通钾肥施用量对其无明显影响.钾素利用率随施钾量提高而降低.氮素利用率大小顺序为NKCNSF,损失率顺序则相反,NK和CN的残留率无显著差异,但均高于SF.控释钾肥施用量对氮素利用率、损失率有显著影响,对残留率无明显影响.     

生物炭的稳定性及其对矿物改性的响应机制研究进展

生物炭具有高度的碳素稳定性,是一种能有效缓解温室效应的固碳材料.研发碳素持留率高和稳定性强的生物炭对固碳减排具有重要意义.矿物改性处理能对生物炭的稳定性起调控作用,但目前相关研究并未得到足够重视,相应调控机理尚不十分清楚.本研究首先对生物炭稳定性的评价指标进行了归纳,主要包括H/C原子比、O/C原子比、稳定性系数R₅₀、挥发性物质含量、碳素热失重率、碳素(化学)氧化损失率、微生物矿化量等.其次,在分析生物炭稳定性影响因素(如原料类型、炭化条件、外界环境等)的基础上,综述了矿物改性对生物炭稳定性影响的研究进展,并探讨了稳定性增强和减弱的响应机制,认为生物炭稳定性的增强响应主要是基于矿物本身的物理阻隔作用,以及矿物与生物炭之间通过交互作用形成的有机矿物复合体对生物炭起到的保护作用,在一定程度上抑制生物炭的降解;而生物炭稳定性的减弱响应则主要与特殊矿物组分有关,例如含铁矿物组分在高温下促进生物炭的降解.最后对未来的研究方向进行了展望,以期进一步推动生物炭固碳减排技术的发展,并为获得稳定性更强的生物炭提供技术支撑和理论依据.     

生物医用高分子材料在药物控释系统中的应用

药物控制释放体系是继传统载药体系发展起来的一种新型的疾病治疗体系。生物医用高分子材料作为药物控释载体的研究逐渐成为热点之一。近年来,随着研究的深入,生物医用高分子材料在药物控释系统中的运用得到了广泛的发展。本文简要介绍了常用天然医用高分子材料如胶原、纤维素以及环糊精和合成医用高分子材料如聚乳酸、聚酸酐等在药物控释系统中的应用,并对这类材料的应用进行了展望。     

有机改性粘土去除有害赤潮藻的研究

本研究以阳离子表面活性剂十六烷基三甲基溴化铵为改性材料,通过粘土颗粒的表面吸附及离子交换作用对粘土进行了表面改性,并以常见于我国沿海的有害赤潮生物种-东海原甲藻(Prorocentrum donghaiense)为目标生物,研究了有机粘土对该藻的去除效果．结果表明,改性后的粘土具有极强的去除赤潮生物能力,当有机粘土的用量为0．01g·L-1时,在24h内东海原甲藻的去除率大于95％。而未经改性处理的原土在相同用量下没有表现出对东海原甲藻的有效去除作用,这表明通过有机改性能显著增强粘土的除藻能力．对有机粘土高效去除机理分析表明。有机粘土表面静电作用、季铵盐离子亲脂性长脂肪链的“网捕”作用及粘土颗粒表面局部高浓度季铵盐离子的灭杀作用是有机粘土具有强去除藻细胞能力的主要原因．     

基于功能高分子材料的生物被膜构建及其生物转化应用进展

生物被膜是微生物附着在载体材料表面的高度有组织的微生物群体,主要由菌体和微生物的胞外分泌物构成。与浮游细菌相比,生物被膜内的微生物对抗菌剂、恶劣环境及宿主免疫防御机制的抗性显著增加,还具有自增殖、可重复利用等优点。近年来,生物被膜在污水处理、工业发酵、食品工程和生物制药等领域受到越来越多的关注。载体材料的理化性质对生物被膜的构建具有重要影响。有机高分子材料因价廉、具有较轻的比重和密度、易于表面改性等特点,成为介导生物被膜构建的优选载体材料。本文对水凝胶、高分子分离膜、聚合物纤维膜及移动床生物膜反应器(MBBR)载体等几大类功能高分子材料促进生物被膜构建及其生物转化应用研究进行综述,以期为相关科研工作者提供参考。     

Fixation and release of potassium and ammonium ions in Danish soils

Summary Results of a laboratory investigation showed that among soils in Denmark it are chiefly those rich in clay minerals that will fix and release potassium and ammonium. The two cations were fixed in nearly equivalent proportions, but ammonium was fixed preferentially to potassium when added together to the soil. The maximum fixation reached 20 to 30 per cent of the addition in top soil layer but 50 to 80 in subsoil. Soils from a permanent fertilizer experiment showed the strongest fixation and least release of potassium where no potassic fertilizer had been applied for more than 70 years. In soils from another field experiment on residual effect of various nitrogenous fertilizers there was a small but significant increase in content of inorganically fixed ammonium where urea had been applied.     

Soil beidellite and its relation to problems of potassium fertility and poor response to potassium fertilizers

Summary X-ray diffraction studies were made on soils with and without potassium fertility problems. All soils with clay fractions containing dominant beidellite or vermiculite showed potassium deficiency and lack of response to potassium fertilizer applications. All of the soils containing dominant montmorillonite or other clay minerals contained adequate potassium; on none of these, poor potassium response was reported. Special management practices are needed on the beidellitic and vermiculitic soils to increase potassium and ammonium fertilizer efficiency. Dominance of beidellite in the clay fraction should be reflected in soil classification. Establishment of a ‘beidellite’ family differentiating criterion in the Soil Taxonomy is proposed for this purpose.     

黄壤稻田土壤微生物生物量碳磷对长期不同施肥的响应

本研究以进行了22年的黄壤稻田长期定位试验为依托,分析了不同施肥模式下土壤碳(C)、磷(P)与微生物生物量C(MBC)、P(MBP)的变化及其耦合特征,旨在探讨黄壤地区合理培肥模式以提高土壤磷素有效性.试验包括10个处理,分别为不施肥(CK)、单施氮肥(N)、磷钾配合(PK)、氮钾配合(NK)、氮磷配合(NP)、氮磷钾配合(NPK)、单施有机肥(M)、3种有机无机肥配施(1/4M+3/4NP、0.5MNP、MNPK).结果表明:与不施肥相比,N和NK处理土壤有机碳(TOC)、全磷(TP)、MBC、MBP均有不同程度的降低,施磷处理(PK、NP、NPK)则有不同程度的提升;与不施肥和施用无机肥相比,施用有机肥各处理TOC、MBC、MBP及MBP/TP均显著增加,其中M和MNPK处理增幅最大.MBC/MBP、TOC/MBP、MBC/TP以施用有机肥处理最低,N处理最高.土壤MBC、MBP及其耦合关系与土壤TOC和有效磷均呈极显著相关,TOC是影响MBC、MBP、MBP/TP的直接因素,而有效磷则是影响MBC/MBP、TOC/MBP、MBC/TP的直接因素.土壤MBP及碳、磷耦合关系各指标可以有效区分单施化肥和施用有机肥的不同施肥方式,可作为评价黄壤稻田磷素肥力的生物学指标.配施有机肥是增加黄壤稻田磷有效性、提高土壤供磷潜力和保持土壤生物健康的有效途径.     

Dynamic role of “illite-like” clay minerals in temperate soils: facts and hypotheses

Analysis of new data and reinterpretation of published information for clay minerals found in temperate climate soil profiles indicates that there is often a gradient of “illite-like” clay minerals with depth. We used the term “illite-like” because these observations are based on X-Ray Diffractogram patterns and not on layer charge measurements which allow to define properly illite. It appears that “illite-like” layers are concentrated in the upper, organic - rich portion of the soil profile both under grassland and forest vegetation. “Illite-like” layer quantity seems directly related to soil potassium status. Indeed, intensive agriculture practises without potassium fertilization reduce “illite-like” content in surface soils, whereas several years of potassic fertilization without plant growth can increase “illite-like” content. The potassic soil clay mineral, illite, is particularly important in that it can be the major source of readily available potassium for plants. Spatial and temporal dynamics of clay minerals should be related to the potassium cycle. We propose that the frequently observed general trend of increasing exchangeable potassium in the top soil can be correlated with an increase in “illite-like” in the clays and that the decrease of potassium caused by intensive agricultural practices leads to “illite-like” layer destabilization. This vision of “illite-like” layer as a potassium reservoir refueled by plants and emptied by intensive cropping renews the concept of potassium availability and indicates a need to be discussed as well in natural ecosystems as in cultivated ecosystems.     

Transport of charged macromolecules across a biological charged membrane

The glomerular capillary wall of the kidney behaves as an electronegatively charged structure consisting of three layers, the lamina densa and the two laminae rarae, which are differently charged. Thus, a three layer model is proposed to analyse the transport of charged macromolecules across this wall. A modified Nernst-Planck equation describes the macromolecule flux across the wall and a Donnan equilibrium is assumed at each interface. For a given value of the fixed charge concentration in each layer, the local sieving coefficient of the macromolecule, i.e. the ratio between the concentrations in the filtrate and in the plasma, is calculated. A sieving curve which relates the sieving coefficient to the Einstein-Stokes radius of the macrosolute is obtained. The fixed charge concentrations in each layer are iteratively modified until simultaneous adjustment is achieved between calculated and experimental curves, for positively and negatively charged tracers and their neutral equivalent.     

Potassium solubilising bacteria (KSB) isolated from rice paddy soil: from isolation,identification to K use efficiency

The present study was intended to isolate potassium-solubilizing bacteria (KSB) from paddy rhizosphere soil. The isolates were obtained from 40 rice paddy fields across Mazandaran province in northern Iran and screened for their K-solubilizing ability on modified Aleksandrov agar medium. The three selected isolates which showed the best solubilisation of potassium were identified using molecular marker 16S rDNA sequencing. The isolates were identified as Pantoea agglomerans, Rahnella aquatilis and Pseudomonas orientalis. From the flame photometry results, the amounts of potassium released by the isolates from mica at 21st day of incubation were 35.36, 76.04 and 56.58 μg ml^?1, respectively. The estimated optimal growth temperature (Ts) were 26.38, 29.17 and 26.80 °C based on segmented model analysis. The pH values of the culture medium with ranges from 6.75–7.26, had a more positive effect on the solubilization of potassium-bearing minerals. The pot experiment results showed that the inoculums of all three KSB enhanced the amount of grain yield and K uptake compared to the control treatment (without K fertilizer). Values were higher when KSB inoculums were used with ½ K chemical fertilizer (47.5 Kg/ha). Bacterial inoculums also increased K use efficiency (AE, PE, APE, ARE and UE) in plants. In conclusion, these findings have successfully demonstrated the effectiveness of locally isolated PGPR with multiple beneficial characteristics such as K solubilizing, IAA production and tolerance to different environment stresses. Therefore, they can be used as biofertilizers to enhance the availability of potassium in the soils and to improve the growth and yield of rice.     

主成分分析在指导红薯施肥中的应用--以漂白湿润淋溶土为例

漂白湿润淋溶土表层的有效钾、全磷、有效磷含量显著高于表下层,其它养分上下两层的含量差异尽管没有达到的显著性水平,但都有向表层集中的趋势.主分量分析结果表明,第一主分量是含氮有机质形成过程强度的量度,表层和表下层有机质、全氮、全磷、有效氮、表下层有效磷均对第一主分量有较大的正向负荷量.第二主分量表示含氮有机质形成过程强度大致相同的情况下,各种养分对红薯产量促进作用的量度,其中表层和表下层有效钾、表下层有效磷对第二主分量的负荷量最大,远远超出其它因素的作用.相关分析也表明,三者与红薯产量呈极显著正相关.这间接表明,将钾肥施入表层和表下层均能提高红薯产量,磷肥只有施入表下层才有增产效果,而氮肥目前不表现增产作用.以上结论为肥料三要素组合试验所证实.这意味着在不改变变量属性的前提下,把多个变量按照变量的特性组合成少数新变量用来解决多因素复杂问题的主分量分析方法,能够科学地、合理地指导作物施肥。     

长期不同养分投入对土壤养分和水稻生产持续性的影响

以中国科学院桃源农业生态试验站15a长期田间定位试验为研究对象,分析了不同养分投入对稻田土壤养分和水稻产量可持续性的影响.结果表明,化肥与系统内循环的有机物料循环的肥力效力和产量效应基本一致,有机物料循环更有利于土壤有机质和氮素的积累;在不同养分投入下,土壤耕层有机质和全氮均呈上升趋势,年均增长率分别为1.5%～5.8%和2.5%～9.4%;与试验前相比,不同养分投入耕层磷素变动幅度在-18.3%到30%之间,钾素养分有所亏缺,下降幅度在8.1%～22.6%之间;通过可持续性指数的分析得出,土壤N素养分的可持续性对化肥的依赖性较大,而P、K养分的可持续性则对有机肥的依赖性更高.稻田生态系统具有良好的自维持能力,系统内有机物循环有利于提高稻谷产量的稳定性和可持续性.     

有机无机肥分次配施对嘎啦苹果生长、15N-尿素吸收利用及损失的影响

以15年生嘎啦苹果/平邑甜茶为试材,采用¹⁵N同位素示踪技术,研究有机无机肥分次配施对嘎啦苹果/平邑甜茶生长、¹⁵N-尿素吸收利用及损失的影响.结果表明: 与不施有机肥相比,有机无机肥配施显著提高了植株根冠比、叶绿素含量、单株叶片总氮量和单果质量,且有机无机肥分次配施的效果要优于有机无机肥一次性配施.有机无机肥配施提高了各器官对氮的吸收征调能力(Ndff值),其中有机无机肥分次配施的效果更显著;而不同施肥处理各器官的Ndff值均表现为果实最高,其次是叶片、一年生枝、细根、粗根和多年生枝,中心干最低.有机无机肥分次配施植株总氮量和¹⁵N肥料利用率分别为395.39 g和28.4%,显著高于有机无机肥一次性配施处理(342.77 g和21.1%)和不施有机肥处理(296.41 g和14.6%),而¹⁵N损失率为51.3%,显著低于有机无机肥一次性配施处理(57.5%)和不施有机肥处理(60.6%).     

有机无机肥分次配施对嘎啦苹果生长、15N-尿素吸收利用及损失的影响

以15年生嘎啦苹果/平邑甜茶为试材,采用¹⁵N同位素示踪技术,研究有机无机肥分次配施对嘎啦苹果/平邑甜茶生长、¹⁵N-尿素吸收利用及损失的影响.结果表明: 与不施有机肥相比,有机无机肥配施显著提高了植株根冠比、叶绿素含量、单株叶片总氮量和单果质量,且有机无机肥分次配施的效果要优于有机无机肥一次性配施.有机无机肥配施提高了各器官对氮的吸收征调能力(Ndff值),其中有机无机肥分次配施的效果更显著;而不同施肥处理各器官的Ndff值均表现为果实最高,其次是叶片、一年生枝、细根、粗根和多年生枝,中心干最低.有机无机肥分次配施植株总氮量和¹⁵N肥料利用率分别为395.39 g和28.4%,显著高于有机无机肥一次性配施处理(342.77 g和21.1%)和不施有机肥处理(296.41 g和14.6%),而¹⁵N损失率为51.3%,显著低于有机无机肥一次性配施处理(57.5%)和不施有机肥处理(60.6%).