百菌清在猕猴桃和土壤中残留动态

建立气相色谱法测定猕猴桃和土壤中百菌清残留的方法,方法的检出限为0.005 mg·kg-1,通过对百菌清在猕猴桃和土壤中降解动态研究,表明百菌清在猕猴桃和土壤中的降解半衰期为5.74 d和7.76 d,施药后第35 d,猕猴桃中百菌清未检出,土壤中百菌清残留量为0.012 mg·kg-1,推荐百菌清在猕猴桃上使用的安全间隔期为35 d。     

异菌脲在梨和土壤中的残留降解动态研究

采用乙腈提取、氟罗里硅土层析柱净化、GC-ECD 测定法,研究了异菌脲在梨和土壤中的降解动态和最终残留量.结果表明:异菌脲在梨上的半衰期为12d,施药后45d 的消解率在90豫以上;在土壤中的半衰期为7.8耀7.9d,施药后45d 的消解率在90豫以上.药后7、14、21d 采集的梨中最高残留量为0.37mg/kg,未超过我国国家标准规定5mg/kg 的 MRL值,在梨上的安全间隔期为7d     

桐油包膜材料在土壤中的降解性能研究

以桐油为包膜材料,利用盆栽土壤试验法,并引入土壤降解、失重率测定方法,研究桐油包膜材料在土壤中的降解性能。结果表明:桐油包膜材料随土壤含水量和温度的增加,降解速率加快;土壤pH值增加,降解速率减慢。用动力学方程C=Ce-kt曲线模型进行模拟,土壤含水质量分数20%时,半衰期116 d;土壤含水质量分数30%时,半衰期只有52 d;当土壤温度从15℃上升到35℃时,降解速率常数从0.003 6 g/d上升到0.008 9 g/d。土壤pH值从4.0上升到6.0时,速率常数下降0.009 2 g/d。     

有机磷农药污染土壤的氧化及水解修复技术初步研究

以天津某农药厂有机磷污染土壤为研究对象,采用化学修复技术中的过硫酸盐氧化和碱催化水解(碱解)对污染土壤中的对硫磷和甲拌磷进行了降解修复,探讨了不同氧化剂投加量(1%、3%、5%)和不同碱解条件(pH值10.5、11.5、12.5)在不同养护时间(7d、14d、21d)条件下,土壤中有机磷农药的降解效果。结果表明:化学氧化和碱解技术都能有效降解土壤中的有机磷污染物;化学氧化相比碱解技术,有机磷污染物降解效果更显著、效率更高,对硫磷和甲拌磷的氧化降解最高去除率可分别达到68.5%和78.8%,碱解降解最高去除率分别为48.5%和43.9%;化学氧化的最佳养护时间为7d,碱解的最佳养护时间为14d。     

石油-重金属复合污染土壤的微生物修复研究

以山东省黄河三角洲孤岛油区石油-重金属复合污染盐碱土为研究对象,通过测定土壤在不同时期的脱氢酶活性、微生物生物量碳、石油烃含量,研究了微生物在石油-重金属复合污染盐碱土修复过程中降解石油的作用。研究结果表明:微生物能促进石油烃的降解,60d后,添加降解菌的实验组和未添加降解菌的对照组石油烃平均降解率分别为45.60%和17.57%。加菌的实验组微生物活性高于对照组,15d时土壤脱氢酶活性实验组比对照组高出25.98%,微生物生物量碳实验组比对照组高出43.76%。     

多代连栽桉树人工林林下植被和土壤物理性状的变化

【目的】林下植被抚育是桉树人工林的重要经营措施之一,研究多代连栽桉树人工林林下植被与土壤渗透性能等物理性状的变化为科学管理林下植被提供依据。【方法】通过调查不同连栽代次桉树人工林林下植被多样性和生物量、枯枝落叶现存量、土壤容重、渗透性能等指标,分析了林下植被和土壤物理性状的变化。【结果】1）随着连栽代次的增加,桉树林下植被Margalef丰富度指数呈现先增加后降低的变化趋势,在种植前期对林下植被丰富度有促进作用,而Pielou均匀度指数表现出下降趋势,说明连栽导致林下植被种间的个体差异变大;2）随着连栽代次的增加,桉树林地土壤孔隙度、持水量、渗透性能和土壤蓄水量大致呈现先增加后降低的变化趋势,而土壤容重变化趋势则相反,表明种植前期土壤物理性能不断得到改善,第4代是生产经营者需注重改善土壤物理状况的关键阶段;3）通过相关分析发现林下植被Margalef丰富度指数与毛管持水量和田间持水量呈显著正相关;林下植被生物量与容重呈显著负相关,与最大持水量和部分孔隙度指标呈现显著正相关;枯枝落叶现存量与总孔隙度、渗透性能指标呈显著或极显著正相关;土壤孔隙状况和持水性能受林下植被的影响更大,土壤渗透性...     

生草对山核桃林地土壤养分及土壤酶活性的影响

[目的]采用人工生草和清耕的方法,对比分析了油菜、绵枣儿、野豌豆3种不同生草处理对山核桃林地土壤养分及土壤酶活性的影响,以期为山核桃生态栽培管理中林下生草提供理论依据.[方法]山核桃林下设置3种人工生草及清耕4个处理,4年后对林下各生草处理土壤酶及土壤养分进行方差分析及相关性分析.[结果]山核桃林下不同生草处理后,0～...     

间伐后环境的改变对植物多样性的影响

以河北省围场县境内华北落叶松人工林为研究对象,通过对其间伐林分和未间伐林分林下灌草的调查以及林下光照条件、土壤理化性质的测定,分析其测定指标的相关关系对林下灌草生长的影响。结果表明,间伐后2年,Shannon多样性指数的提高与林冠覆盖度与土壤毛管空隙度存在极显著相关性。林冠覆盖度与土壤总孔隙度、毛管孔隙度及土壤容重存在显著相关性(P<0.05)。而总孔隙度与毛管孔隙度及土壤容重存在极显著相关性(P<0.01),与土壤非毛管孔隙度则存在显著相关(P<0.05)。针对主成分分析而言,光照及其土壤孔隙度与土壤的营养元素共同影响着林下草本的多样性,但是根据之前对各项指标的方差分析中发现,土壤中的营养元素含量之间并不存在显著性差异,因此,对林下草本多样性短期影响的主要因素为光照(林冠覆盖度、林冠均匀度)和水分(土壤毛管含量)。     

梅花鹿林下养殖对林地土壤理化性质的影响

通过测定梅花鹿林下养殖林地土壤的容重、总孔隙度、含水量、全氮、全磷、速效磷和速效钾等物理化学指标,确定梅花鹿养殖对林地土壤理化性质的影响及干扰程度,并探究土壤对梅花鹿林下养殖干扰的响应。研究发现随着梅花鹿林下养殖密度的增大,林地土壤容重随之增加,孔隙度减小,含水量降低,土壤中全氮、全磷、速效磷、速效钾含量呈现先增加后随之减小的现象。梅花鹿养殖区域林下土壤的理化性质的变化受到梅花鹿养殖及其密度影响,适度的放养有利于土壤物理性质的改善,增加土壤营养成分的沉积。养殖密度一但超过承载量,将造成土壤的物理性质下降以及营养成分的流失。     

林分密度对华北落叶松天然次生林林下植被和土壤呼吸的影响

为实现“碳中和”背景下的森林高质量经营,探索林分密度调控对森林生态系统土壤呼吸和林下植被物种多样性的影响具有非常重要的意义。以山西五台山林区华北落叶松（Larix principis-rupprechtii）天然次生林为研究对象,设置不同林分密度样地,调查林下植被物种多样性并测定土壤呼吸速率,分析林分密度对林下植被物种多样性和土壤呼吸速率的影响以及物种多样性和土壤呼吸速率的耦合关系。结果表明,喜光植物的重要值随林分密度增加而逐渐降低,在高密度林分中变成偶见种或消失,耐荫植物的重要值随林分密度增加而升高,在高密度林分中成为代表性种。林下植被物种多样性和土壤呼吸速率均随林分密度增加均呈先上升后下降的趋势;香农-威纳指数、辛普森指数、基于香农-威纳指数的均匀度指数、基于辛普森指数的均匀度指数和物种丰富度指数均在中密度下达到峰值,土壤呼吸速率也在中密度下达到峰值;植被种类、林下植被物种多样性指数与土壤呼吸速率的相关性极强,其中物种丰富度指数对土壤呼吸速率的影响最显著。     

Über den Abbau von Quintozen in Gemüsekulturen und gärtnerisch genutzten Erden (Teil 1)

Studies on the degradation of quintozene in vegetables and soils of gardeners In the Federal Republic of Germany the application of quintozene containing pesticides was allowed at vegetables and flowers with some restrictions until 1973. This is the reason why now, in 1976, soils of gardeners and green-houses are contaminated with quintozene (PCNB), hexachlorobenzene (HCB) and pentachloroaniline (PCA). PCA residues are generally found in higher concentrations than the HCB and PCNB residues. Plants, especially leaves and root vegetables, which are cultivated on those soils can be contaminated with HCB, PCNB and PCA residues originating from the soil. The extent of PCA-residues was unknown until now because PCA residues could not be measured by some known analytical methods. Therefore, PCA-tolerances could not yet be established.     

Use of plastic formulations of chlorpyrifos and sumithion as mosquito larvicides and their delayed effects on the basal follicle numbers developed by female survivors

Tests were conducted to evaluate the larvicidal effectiveness of three controlled-release plastic formulations of both chlorpyrifos and sumithion against mosquito larvae ofCulex pipiens. Excellent control with 90–100% larval mortality was achieved for 85, 77, 73, and 64, 54, 48 days posttreatment by using the non-expanded, expanded and foamed formulations of chlorpyrifos and sumithion, respectively. Apart from lethal action, larval treatments with the above formulations led to an increase in the mean number of basal follicles developed by mosquito females which survived from these treatments. The increase in this mean per female was in respect 23.4, 30.0, 18.7% in case of chlorpyrifos formulations, and 21.8, 17.2, 26.8% in case of sumithion formulations.     

Zur Frage von Chlorfenvinphos-und 2,2′,4′-Trichloracetophenon-Rückständen bei Gemüsekulturen und in gärtnerisch genutzten Erden.Teil 1

The present work illustrates the situation of chlorfenvinphos and supposed trichloroacetophenone residues in vegetables and horticultural soils. For that purpose, samples of radishes, cucumbers, cress and soils were analysed. The received results admit — in connection with residue results that are given in literature — the following statements and conclusions:

1. After applications of chlorfenvinphos containing plant protectives chlorfenvinphos residues can remain in soils for half a year or longer. However, chlorfenvinphos is completely metabolized within a defined period and thereafter it cannot be detected. Therefore, repeated applications of chlorfenvinphos containing plant protectives should not lead to a continued accumulation of chlorfenvinphos in soils.
2. Trichloroacetophenone, the hydrolysis product of chlorfenvinphos with boiling half concentrated sulfuric acid, could not be detected in any sample of soils investigated by us — even after 30 applications of the chlorfenvinphos containing plant protective Birlane Granulat at the same area during the last 10 years.
3. A proof for the purpose that chlorfenvinphos is metabolized in vegetables to trichloroacetophenone cannot be given. Also trichloroacetophenone residues in vegetables resulting from soil can be excluded. From this point of view, it seems not to be necessary to establish a tolerance for trichloroacetophenone.
4. After application of Birlane Granulat the German waiting-time for radishes is 30 days and the waiting-time for cucumbers is 60 days. These waiting-times seem to be practically as shown in this work.
5. When Birlane Granulat is applicated to a certain plant culture, not only this culture but following cultures of plants can be contaminated with chlorfenvinphos over a certain period. The results of experiments with cress as following plant culture give rise to the conclusion that cress can contain higher chlorfenvinphos residues as admitted within a period of three months and more after application of Birlane Granulat.

     

Determination of susceptibility and resistance of some greenhouse populations of Tetranychus urticae Koch to chlorpyrifos (Dursban 4) by the petri dish–Potter tower method

The level of susceptibility of the two-spotted spider mite, Tetranychus urticae Koch, populations collected from greenhouses in Antalya and Isparta regions of Turkey against chlorpyrifos was determined by a petri dish bioassay method. This study consisted of two stages. In the first stage, using a diagnostic dosage (0.026 ml chlorpyrifos in 100 ml distilled water) it was determined whether these populations are resistant or susceptible to chlorpyrifos. Then, different dosages of chlorpyrifos were applied to resistant populations to determine LC₅₀ and LC₉₀ values. Resistant ratios of populations were calculated by dividing the LC₅₀ values of resistant populations by that of a susceptible population of T. urticae strain GSS. The resistance ratio of T. urticae populations collected from greenhouses ranged from 8.00 to 1,774.00. Results show that while three of the populations gathered from the Isparta region, where greenhouse vegetable growing has been increasing since 2000, are susceptible, two of them are only partially resistant to chlorpyrifos. On the other hand, all the two-spotted spider mite populations collected from the Antalya region, the centre of greenhouse vegetable production for many years, were found to be highly resistant to chlorpyrifos.     

Inheritance and detoxification enzyme levels in <Emphasis Type="Italic">Tetranychus urticae</Emphasis> Koch (Acari: Tetranychidae) strain selected with chlorpyrifos

Changes in insecticide susceptibilities and detoxifying enzyme activities were measured in a strain of Tetranychus urticae Koch following repeated exposure to the organophosphate insecticide, chlorpyrifos. Twelve consecutive selection at the LC₆₀ of the parental strain increased resistance from 8.58 to 91.45 fold. The interaction of some synergists [piperonyl butoxide, triphenyl phosphate and S-benzyl-O,O-diisopropyl phosphorothioate (IBP)] with chlorpyrifos was analyzed in the selected strain. Solely IBP showed a low synergistic effect with chlorpyrifos. The selected strain also demonstrated resistance against abamectin, propargite, clofentezine and fenpyroximate. The mode of resistance inheritance to chlorpyrifos was found to be incompletely dominant, and not sex-linked. Non-specific esterase enzyme activity was raised from 19.35 to 33.59 mOD/min/mg proteins during the selection period and it was observed that esterase band intensities visualized by polyacrylamide gel electrophoresis increased. This study has investigated the selection of resistance to chlorpyrifos and documented resistance to abamectin, propargite, clofentezine and fenpyroximate in Turkish T. urticae. Esterase enzymes may be playing a role in chlorpyrifos resistance while glutathione S-transferase (GST) and P450 enzymes do not appear to have any significant involvement.     

Release of mineral nutrients and heavy metals from wood and peat ash fertilizers: Field studies in Finnish forest soils

Two field trials were conducted to study the rate of release of nutrients and heavy metals from wood and peat ash fertilizers in forest soils. In the first experiment, ash particle residues were extracted from peat and mineral soils 3 and 5 years after spreading and analysed for changes in element concentrations. Dissolution of different ash fertilizer products was also estimated by measuring the changes over time in the recovery of added nutrients and heavy metals in the surface of two peat soils. The results showed that potassium (K), sodium (Na), boron and sulfur are easily released from wood ash, whereas heavy metals are highly insoluble in all types of ash fertilizer products. Granulated ash fertilizers were less soluble than powdered fertilizers and the products stabilized by self-hardening. Minor differences occurred in ash fertilizer dissolution between peat and mineral soils and soils of different fertility. The most significant difference between wood and peat ash concerning their dissolution was the low solubility of K and Na in peat ash. Given the very slow dissolution of ash fertilizers, long-term studies are needed to understand fully the effect of ash fertilization on nutrient and heavy metal cycling in forest ecosystems.     

Changes in soil properties and vegetation characteristics along a forest-savanna gradient in southern Venezuela

Vegetation cover in the Gran Sabana highlands (southern Venezuela) appears as a complex mosaic of tall to low forests, bush vegetation and savannas. In this study we described the changes in structure and floristic composition along a forest-savanna gradient consisted of tall forest (TF), medium forest (MF), low forest (LF) and open savanna (S), and analyse the possible reasons for the observed changes. The results showed no obvious differences in the soils properties along the vegetation gradient. All sites presented shallow soils (<50 cm depth) with high percentage of sand and with dominance of quartz, kaolinite and oxides of iron and aluminum. The soil chemical characteristics were unfavorable and similar along the vegetation gradient. The major soil difference was related with the presence of an organic layer on the soil surface of TF and MF and their absence on the soils of LF and S. Abundant residues of large trees were found on the forest floor of TF, MF and LF. These residues presented no signs of burning in TF, while in MF and particularly in LF were charred. This observation joined to the presence of charcoal within the mineral soil of S and the absence of the organic surface layer in LF and S indicated that fire has affected with different intensity or frequency the studied vegetation gradient. Large differences in the structure and floristic composition were found between TF, MF, LF and S. These differences could not be explained by changes in the mineralogical and chemical characteristics of the soil but only by fire which triggers the conversion. We concluded that the studied vegetation gradient represents stages in a temporal change from forest to savanna caused by fire, and this change has implied an impoverishment of tree species, a drastic reduction of biomass in terms of basal area, a drastic change of the floristic composition and the loss of the organic surface layer, which play an important role to maintain the fertility of these soils.     

Environmental influences on nitrogen transformation of different quality tree litter under submerged and aerobic conditions

Trees in farming systems can improve fertility of soils through mineralization of N in their litter. This study was to determine the quality parameters (i.e., chemical composition) of organic residues that are associated with N mineralization in soils under submerged and aerobic conditions, and to demonstrate that aeration conditions should be taken into account in categorization of organic residues as N sources in farming systems. Incubation experiments were conducted in Aeric Paleaquult soil under submerged and Oxic Paleustult soil under aerobic conditions. Treatments included litter and some fresh materials from trees as well as rice straw available in farming systems of Northeast Thailand. S. grandiflora and L. leucocephala (32 g kg⁻¹ N) had the highest net N mineralization in both conditions. Some lower-quality (< 20 g kg⁻¹ N) residues did exhibit low net N mineralization during the 16-week period under submerged conditions, but displayed almost no net N mineralization in aerobic conditions. Under submerged conditions, their net N mineralization was higher and more rapid. The nitrogen content of the residues was the most important factor controlling N mineralization under both conditions. Polyphenols exerted the highest negative influence on N mineralization in aerobic conditions, but exhibited no negative effect in submerged conditions. In categorizing organic residues for their effective use in soil fertility management, soil aeration conditions, as well as other environmental factors, should be taken into consideration in addition to residue quality.     

Pentachlornitrobenzol-, Pentachloranilin- und Methylthiopentachlorbenzol-Rückstände bei Gemüsekulturen und in gärtnerisch genutzten Erden

In horticultural soils, pentachloronitrobenzene (PCNB, common name: quintozene) can be metabolized either by reduction of the nitrogroup to pentachloroaniline (PCA) or — formally regarded — by nucleophilic exchange of the nitro — against the methylthio-group to methylthiopentachlorobenzene (MTPCB). Formation of MTPCB from PCA in horticultural soils can be excluded.The residues of the metabolite MTPCB in horticultural soils in the period immediately following the date of application of PCNB containing pesticides can be in the same range as the residues of the metabolite PCA or they can exceed the PCA-residues. Then, in comparison with the PCA-residues the MTPCB-residues in horticultural soils disappear more rapid than the PCA-residues. The quotient MTPCB/PCA becomes the smaller the longer removes the date of sample-taking from the date of application of PCNB containing pesticides. These results indicate that MTPCB is not so persistent as PCA in horticultural soils. This statement can be proofed furthermore by the PCA-and MTPCB-residues measured in 1975/1976 in horticultural soils originating from areas to which Brassicol^®, a PCNB containing pesticide, was applicated before or up to 1972: the MTPCB-residues are generally 1/10 or less of the PCA-residues.Leaves or root vegetables grown as following cultures of lettuce on fields to which Brassicol^® was immediately applicated before cultivation of lettuce contain during a certain period HCB (hexachlorobenzene)-, PCNB-, PCA-and MTPCB-residues. Usually, in leaves vegetables, the MTPCB-residues are smaller than the PCA-residues of the same samples. However, in root vegetables, the MTPCB-residues of the same samples can be in the same range as the PCA-residues or can exceed the PCA-residues.Leaves or root vegetables grown in different periods in 1974 to 1976 on horticultural soils to which Brassicol^® was applicated before or up to 1972 usually contain no detectable or only small residues (in the range of 0,02 ppm) of MTPCB. Fruit vegetables grown on these soils does not contain either HCB-, nor PCNB- nor PCA, nor MTPCB-residues in detectable quantities.

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Mit 2 Abbildungen     

Properties of humic acids in Mediterranean forest soils (Southern Italy): influence of different plant covering

The chemical and spectroscopic properties of humic acids (HAs) isolated from four litters and their corresponding underlying soils at three depths in a protected forest area in Southern Italy were investigated as a function of four different plant coverings: Quercus ilex L., mixed Carpinus betulus L. and C. orientalis Mill., Pinus halepensis L., and mixed Quercus trojana Webb. and Q. ilex L.. The forested site is a part of a calcareous plateau, characterized by homogeneous soils classified as Eutric Cambisols associated with Calcic Luvisols. The changes in the composition of HAs with soil depth have been evaluated on the basis of chemical (elemental and COOH groups) and spectroscopic analyses (E₄/E₆ ratio and FT IR spectra), and lignin-derived CuO oxidation products. A different distribution of the main elements was found in the various HAs which is apparently related to the type of humic acid-precursor biomolecules in the parent litters. The HAs isolated from soils under Q. ilex and mixed Carpinus species showed a slight increase in the C/H ratio and COOH content downward the soil profile, suggesting increasing aromatic polycondensation and humification degree with depth. On the contrary, no trend was observed for HAs from soils under Pinus halepensis L. and mixed Quercus species, indicating a partial incorporation of residues deriving from litter degradation into these HAs. Further, the content of lignin-derived phenols was higher in Pinus halepensis L. and mixed Quercus species layers, with the same trend measured for the corresponding HAs, thus confirming a lignin contribution related to the lignin type of plant covering.