共查询到20条相似文献，搜索用时 656 毫秒
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桐油包膜材料在土壤中的降解性能研究 总被引：1，自引：0，他引：1
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。 相似文献
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《绿色科技》2020,(14)
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。 相似文献
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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)。 相似文献
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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。 相似文献
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[目的]探讨林下植被不同管理措施对培育杉木大径材林分土壤酶活性及土壤质量的影响。[方法]本研究以培育杉木大径材林分为研究对象,分析了林下植被保留(UP)、林下植被去除(UR)和林下套种(IP)3种林下植被管理措施培育杉木大径材林分土壤酶活性差异,并以土壤酶作为土壤生物活性指标,结合土壤物理和化学性质,利用主成分分析法对土壤质量进行综合定量评价。[结果]IP处理提高了0～20 cm土层蔗糖酶活性,而20～40、40～60 cm土层3种林下植被管理措施间土壤蔗糖酶活性差异较小;相比于UR和IP处理,UP处理提高了土壤过氧化氢酶活性,脲酶活性则相反,UR和IP处理间土壤脲酶和过氧化氢酶活性差异较小;3种林下植被管理措施下,土壤酸性磷酸酶活性高低排序为IPURUP,多酚氧化酶活性高低排序为UPIPUR;林下植被不同管理措施间土壤脲酶、蔗糖酶和多酚氧化酶活性差异较大,其中,多酚氧化酶对于林下植被管理措施的响应更灵敏,且能反映于较深土层;除酸性磷酸酶活性外,其余土壤酶活性均具明显表聚性,且随土层加深而递减。有机质和水解性氮含量与各种土壤酶活性具有极显著或显著正相关;有效磷含量与蔗糖酶、脲酶和酸性磷酸酶活性呈极显著正相关;速效钾含量与蔗糖酶、过氧化氢酶和多酚氧化酶活性呈极显著正相关;土壤物理性质与土壤酶活性相关性较弱。将土壤酶活性作为土壤质量指标之一,结合土壤物理性质和化学性质,通过主成分分析提取出3个主成分,反映了原信息量的75.31%。林下植被不同管理措施的土壤质量指数排序均为:IPUPUR。[结论]培育杉木大径材林分中,林下套种楠木的林下植被管理措施对于保持和提升土壤质量效果最佳,其次为林下植被保留措施,林下植被去除措施的效果较差。 相似文献
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林下种养对油茶林地土壤磷素形态及含量的影响 总被引：1，自引：0，他引：1
为了探究不同种养模式对油茶林地土壤磷素含量的影响,对油茶林下养鸡、林下种草、间种花生和间种大豆4种林下种养模式下林地土壤磷素形态变化和含量进行研究。结果表明:不同模式下油茶林地根际土壤中有效磷含量显著高于非根际土壤,显著提高0~20 cm土层中有效磷含量,其中间种大豆的效果最显著;林下养鸡和林下种草显著提高油茶林地根际土壤和非根际土壤中全磷含量,间种花生和间种大豆对其影响不显著;不同模式下Al-P和Fe-P的含量均显著高于O-P和Ca-P,其中林下种草能显著提高根际Ca-P含量。 相似文献
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M. Häfner 《Journal of pest science》1976,49(12):177-183
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. 相似文献
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Dr. Moustafa S. Saleh 《Journal of pest science》1988,61(1):14-17
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. 相似文献
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M. Häfner 《Journal of pest science》1980,53(7):102-106
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:
- 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.
- 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.
- 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.
- 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.
- 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.
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Recep Ay 《Journal of pest science》2005,78(3):139-143
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. 相似文献
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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. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):146-153
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. 相似文献
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Changes in soil properties and vegetation characteristics along a forest-savanna gradient in southern Venezuela 总被引：5，自引：0，他引：5
Nelda Dezzeo Noemí Chacn Elio Sanoja Gabriel Picn 《Forest Ecology and Management》2004,200(1-3):183-193
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. 相似文献
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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. 相似文献
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Dr. M. Häfner 《Journal of pest science》1978,51(4):49-57
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.
Mit 2 Abbildungen 相似文献
Mit 2 Abbildungen 相似文献
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Andreina Traversa Daniel Said-Pullicino Valeria D’Orazio Giovanni Gigliotti Nicola Senesi 《European Journal of Forest Research》2011,130(6):1045-1054
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. 相似文献