蚯蚓体表液的组成及其减粘脱土机理分析

蚯蚓的体表液利于减粘脱土。本文利用现代测试仪器,结合生物化学分析技术,研究了蚯蚓体表液和泥鳅分泌液的组成;并应用土壤力学和生物化学等方面的理论,初步探讨了蚯蚓体表液减粘脱土的机理。     

The nature of eurytopy in polyploid earthworm species in relation to their use in biological soil amelioration

Summary Many of the most widely distributed species of Lumbricidae are polyploid. So far polyploid forms have been found to be distributed more widely than diploid ones. Taking Eisenia nordenskioldi as an example, it was shown that polyploids are able to occupy new ecological niches within the area of the diploid form. Ecological differences observed in representatives of different chromosomal races provide polyploids with the chance to coexist in one biocurrent, occupying different ecological niches.Dedicated to the late Prof. Dr. M.S. Ghilarov     

Long-term study of growth in the New Zealand flatworm Arthurdendyus triangulatus under laboratory conditions

In a 1-year laboratory study of the New Zealand flatworm Arthurdendyus triangulatus, individual growth, degrowth and regrowth were manipulated via the feeding regime, with the compost worm Eisenia fetida as prey. A mean growth rate of 25 mg live weight wk^—1 was evident, individual rates ranging between 18 and 38 mg wk⁻¹. Degrowth was associated with egg capsule deposition for which the maximum rate was 0.5 capsules wk⁻¹. The more egg capsules produced, the greater the adult weight loss, degrowth rates ranging from 8 to 55 mg wk⁻¹. Change in flatworm body weight (gain/loss) also correlated with the length of the food introduction interval, though weight could be maintained for circa 2 weeks. Weight loss was not simply a function of hunger, voluntary cessation of feeding (possibly related to egg capsule production) being a confounding factor. During the growth phase, individual predation rate ranged from 0.9 to 1.1 earthworms wk⁻¹, rate of tissue consumption ranging from 346 to 485 mg wk⁻¹. Conversion efficiencies of earthworm to flatworm tissue were estimated to range between 3.8% and 10.7%. The impact of this exotic planarian on earthworm populations is discussed.     

Spatial distribution of earthworms [Lumbricidae] in recultivated soils of the Rhenish lignite‐mining area,Germany

The spatial distribution of earthworms was studied by means of combined formalin expulsion and hand sorting in three arable fields of the Rhenish lignite‐mining area that differed in their recultivation age (6, 12, 24 yr). In addition, pH and the spatial distribution of penetration resistances were measured to see if they are corresponding with the distribution of earthworms. Already the 6 yr old field had a rich population of endogeic, anecic, and epigeic earthworms (119 ind. m^–2, 48 g m^–2, 6 species). This quantity was similar to the 24 yr old site. The 12 yr old field was only sparsely populated by earthworms (5 ind. m^–2, 5 g m^–2, 3 species). In the 6 yr old field, the spatial distribution pattern showed a center of maximal earthworm abundances, corresponding to the distributional pattern of penetration resistances. In the old field (24 yr), the species varied in their spatial distribution, and there was no correspondence with the distribution of penetration resistance. In general, the penetration resistance at the youngest site was clearly lower than at the two older sites. The earthworm population in the 6 yr old field can be explained by cocoons contained in the dumped material. A calculation using literature data on earthworm‐population dynamics shows that a founding population of 400–600 reproductive individuals per hectare and a continuity of favorable growth conditions during the time of soil management is necessary for the development of the situation found at the 6 yr old site in this study.     

Mucus excretion and carbon turnover of endogeic earthworms

Summary Mucus excretion of endogeic earthworms, by the body surface to burrow walls and by the intestine to casts, was investigated using uniformly ¹⁴C-labelled adult or subadult specimens of Octolasion lacteum (Örley) in laboratory incubations in soil from a beechwood on limestone. The daily loss of C due to mucus excretion from the body surface and in casts was calculated as 0.2 and 0.5% of total animal C, respectively. The C loss due to mucus excretion by subadult or adult individuals of O. lacteum is assumed to account for 63% of total C losses (including mucus excretion and respiration) of the earthworms. In a second experiment we studied the incorporation of ¹⁴C from labelled soil, again from a beechwood on limestone, into the tissue of the endogeic earthworm species Aporrectodea caliginosa (Savigny). The results of this experiment indicate the existence of two C pools, one more labile and one more stable, in earthworms. It is assumed that the C investment for respiration and mucus excretion is derived from the labile C pool of endogeic earthworms.     

Soil conservation on road embankments using palm‐mat geotextiles: field studies in Lithuania

The application of geotextile mats constructed from the palm leaves of Borassus aethiopum (Borassus) and Mauritia flexuosa (Buriti) was investigated in field experiments. The use of geotextiles caused improved soil moisture storage during dry summer periods on a steep (21–25°) roadside slope in Lithuania. The enhanced soil moisture under the Borassus and Buriti mats encouraged better root development of perennial grasses, increased the number and weight of earthworms and increased the dry biomass of perennial grasses by 50.5 and 18.2%, respectively, compared with a grassland control. The mean rate of water erosion from bare soil during the study period from 17/04/2007 to 11/12/2008 was 33.21 Mg/ha. The cover of palm‐mat geotextiles decreased soil losses from bare fallow soil by 94.8–91.1%. An erosion rate of 0.85 Mg/ha over this 21‐month period was measured on the slope under perennial grasses without geotextile cover. Application of geotextile cover on perennial grasses completely prevented soil erosion by water. Therefore, use of geotextiles has clear soil and water conservation benefits on industrial slopes susceptible to erosion. The use of geotextiles has multiple benefits including soil conservation, the improvement of plant growth conditions and the encouragement of earthworm populations.     

土施纳米氧化锌对蚯蚓生理和黄瓜幼苗生长的影响

纳米氧化锌(ZnO NPs)由于其独特的理化性质,被广泛应用于各行各业,在带来巨大利益的同时也存在着潜在风险,如细胞毒性、基因毒性等。在土壤环境中,ZnO NPs可能会对陆地生态系统中的生物构成严重威胁。本研究采用盆栽试验的方法,评估了ZnO NPs对蚯蚓生理以及黄瓜幼苗生长的影响。结果表明:各处理ZnO NPs对蚯蚓的生长发育影响不显著,但随着浓度的增加,蚯蚓的抗氧化酶活性发生变化,SOD呈现出增加的趋势,CAT和POD先降低再上升,二者表现为协同作用。当ZnO NPs处理为1 000 mg·kg-1时,蚯蚓受到的氧化胁迫最大,MDA含量较对照增加了19.2%。对于黄瓜幼苗而言,ZnO NPs处理能够普遍增强植株氧化应激,除了SOD在1 000 mg·kg-1时受到抑制外,SOD、CAT、POD及MDA均随浓度的增加而增加。蚯蚓的加入能显著促进幼苗生长,增加生物量、提高根系活力,同时也能在一定程度上缓解或抑制ZnO NPs对植株造成的损伤。ZnO NPs处理为500mg·kg-1和1 000 mg·kg-1时,SOD分别较不加蚯蚓处理降低了76.7%、63.5%,MDA分别降低了28.6%、23.7%。在28 d培养周期中,蚯蚓对ZnO NPs响应较低,组织锌含量没有显著变化;黄瓜幼苗地上部和地下部锌含量均随着处理浓度的增加而增加,而添加蚯蚓的处理降低了植株的锌含量,也反映了蚯蚓在系统中对胁迫条件下的黄瓜幼苗生长的调控和缓解作用。     

铬(Ⅵ)和菲单一及复合暴露对赤子爱胜蚓的急性毒性效应研究

采用人工土壤试验方法,研究了重金属铬(Ⅵ)和多环芳烃菲单一及复合暴露对赤子爱胜蚓的急性毒性效应.单一暴露试验结果表明:铬(Ⅵ)对赤子爱胜蚓7 d和14 d的LC₅₀分别为259.98 mg·kg^-1和241.13 mg·kg^-1;菲对赤子爱胜蚓7 d和14 d的LC₅₀分别为88.01 mg·kg^-1和60.96 mg·kg^-1.铬(Ⅵ)和菲对赤子爱胜蚓都表现出明显的时间-浓度-效应关系,而且铬(Ⅵ)和菲对赤子爱胜蚓均具有一定毒性,菲的毒性大于铬(Ⅵ).采用铬(Ⅵ)和菲等毒性单位进行复合暴露试验,结果表明铬(Ⅵ)和菲混合物对蚯蚓7 d-LC₅₀中铬(Ⅵ)和菲所含浓度分别为151.73 mg·kg^-1和37.93 mg·kg^-1;14 d-LC₅₀中铬(Ⅵ)和菲所含浓度分别为 137.69 mg·kg^-1和34.42 mg·kg^-1,根据等效应线图判定其联合作用表现为相加作用.