皖南紫红色砂石岩上发育土壤的系统分类研究

对皖南不同时期紫红色砂石岩上发育的8个土壤剖面,按中国土壤系统分类体系,进行鉴别、检索、分类定名。阐述发生分类紫色土的2个亚类级土壤类型在中国土壤系统分类中归为3个土纲,即均腐土、雏形土和新成土;3个亚纲,即湿润均腐土、湿润雏形土和正常新成土;4个土类和6个亚类。提出按中国土壤系统分类的紫色土分类系统;并与美国土壤系统分类、国际土壤分类参比基础进行了参比。讨论了皖南紫红色砂石岩上发育为均腐土的成土环境条件,同时对发生分类紫色土在中国土壤系统分类类别检索提出修订建议。     

用稀悬液Wien效应测量法来研究重金属离子与水稻土的相互作用

Interactions of three heavy metal ions, Cu²⁺, Cd²⁺, and Pb²⁺, and, for comparison, Na⁺ with electrodialytic clay fractions (less than 2 μm in diameter) of four paddy soils as well as a yellow-brown soil as a control soil were evaluated based on measurements of the Wien effect in dilute suspensions with a clay concentration of 10 g kg^?1 in four nitrate solutions of 2 × 10^?4/z mol L^?1, where z is the cation valence, and a nitric acid solution of 3 × 10^?5 mol L^?1. Field strengths ranging from 15 to 230 kV cm^?1 were applied for measuring the electrical conductivities (ECs) of the suspensions. The mean free binding energies between the various cations and all of the soils determined from exchange equilibrium increased in the order: Na⁺ < Cd²⁺ < Cu²⁺ < Pb²⁺. In general, the ECs of the suspensions in the sodium nitrate solution were smaller than those of the suspensions in the heavy metal solutions because of the lower electrophoretic mobility of sodium compared to the divalent cations. In terms of relative electrical conductivity-field strength relationships, relative electrical conductivity (REC) of suspensions containing various cations at field strengths larger than about 50 kV cm^?1 were in the descending order: Na⁺ > Cu²⁺ > Cd²⁺ > Pb²⁺ for all tested soils. A characteristic parameter of the REC-field strength curves, ΔREC₂₀₀, REC at a field strength of 200 kV cm^?1 minus that at the local minimum of the concave segment of the REC-field strength curves, characterized the strength of adsorption of the cations stripped off by the applied strong electrical field, and for all soils the values of ΔREC₂₀₀ were generally in the order: Na⁺ < Cu²⁺ ≤ Cd²⁺ ≤ Pb²⁺.     

Assessing habitat use of the endangered marine mollusc Patella ferruginea (Gastropoda, Patellidae) in northern Africa: preliminary results and implications for conservation

The limpet Patella ferruginea Gmelin, 1791, endemic to the Mediterranean, is the most endangered marine species on the list of the European Council Directive 92/43/EEC on the Conservation of Natural Habitat of Wild Fauna and Flora (1992). Its Mediterranean range has progressively contracted to a few restricted areas and the species is now threatened with extinction. Seventeen stations were sampled along the littoral zone on the coast of Ceuta, North Africa, for quantifying environmental factors (water movement, siltation and suspended solids), and 70 transects were selected for P. ferruginea sampling. The study revealed the presence of a well-established population of P. ferruginea with values of density and size of 0.67 individuals m⁻¹ ±0.96 and 48.94 mm±11.61 respectively (mean±standard error of mean). The biggest densities of P. ferruginea were found inside the harbour of Ceuta. The limpets were more abundant on artificial harbour stones than on natural rocky shores, and the areas under the highest human pressure were characterised by the lowest densities and the smallest specimens probably due mainly to the predation for food and fishing. Human pressure is probably the main contributing factor to the currently endangered status of P. ferruginea. Programmes of environmental education to avoid its collection for fishing, food or for fun as decorative objects should be conducted, and further experimental studies dealing with the reproductive biology of this species are needed to properly assess the future programmes of conservation.     

不同种植模式下紫色土养分流失影响因子研究

通过建立5个不同种植模式的径流小区，对每个小区径流泥沙中养分的含量进行研究．探讨机械组成、微团聚体含量、粘粒团聚度等因子对养分流失影响的程度，结果发现：15～30cm土层中〈0．01mm的粘粒含量与径流泥沙中全钾含量和速效钾含量有显著的相关性。0～15cm层中的〈0．01mm和〈0．001mm微团聚体含量都与径流泥沙中有机质、速效钾和全氮的含量有显著的相关性。同层中〈0．01mm粘粒团聚度与径流泥沙中全氮含量和速效钾含量有显著的相关性，而同层〈0．001mm粘粒团聚度与径流泥沙中全磷含量、速效钾含量和速效磷含量有显著的正相关。     

Arsenic-contaminated soils phytotoxicity studies with sunflower and sorghum

Background, Aim and Scope  Environmental pollution caused by arsenic (As) is a major ecological problem. There has been intense worldwide effort to find As-hyperaccumulating plants that can be used in phytoremediation—the green-plant-assisted removal of chemical pollutants from soils. For phytoremediation, it is natural to prefer cultivated rather than wild plants, because their agriculture is well known. This study was conducted to evaluate the tolerance of common sunflower(Helianthus annuus L.) and sugar sorghum(Sorghum saccharatum Pers.) for soil-As contents of 10–100 mg As kg^-1 soil, with sodium arsenite as a model contaminant. Methods  Plants were grown in a growth chamber for 30 days. Microfield experiments were conducted on experimental plots. To study the phytoremediation effect of the auxins indole-3-acetic acid (IAA) and 2,4-dichlorophenoxyacetic acid (2,4-D), we treated 1- and 3-day-old plant seedlings with water solutions of the auxins (concentrations 10^-5, 10^-7, and 10^-9 g l^-1). The soil and plant-biomass samples were analyzed for total As by using the color reaction of ammonium molybdate with As. Results and Discussion  Phytotoxicity studies showed that 100 mg As kg^-1 soil poisoned sunflower and sorghum growth by 50%. There was a linear correlation between soil-As content and As accumulation in the plants. Laboratory experiments showed that the soil-As content was reduced two- to threefold after sunflower had been grown with 10–100 mg As kg^-1 soil for 30 days. Treatment of sunflower and sorghum seedlings with IAA and 2,4-D at a concentration of 10^-5 g l^-1 in microfield experiments enhanced the phytoremediation two- to fivefold as compared with untreated control plants. The best results were obtained with 3-day-old seedlings. Conclusion, Recommendation and Outlook  (a) Sunflower and sorghum are good candidates to remediate As-polluted soils. (b) Phytoremediation can be improved with IAA or 2,4-D. (c) Mixed cropping of sorghum and sunflower may be another way of improving phytoremediation.     

Effects of sewage sludge amendment on humic acids and microbiological properties of a semiarid Mediterranean soil

The residual effects of adding 40 t ha^–1 sewage sludge (SL) to a degraded soil cropped with barley were investigated after 9 and 36 months in a field experiment under semiarid conditions. The principal soil properties were apparently still affected by SL amendment 9 months after application but the effects disappeared after 36 months. With respect to control soil humic acids (HAs), the SL-HA was characterized by higher contents of S- and N-containing groups, smaller contents of acidic groups, a prevalent aliphaticity, extended molecular heterogeneity, and smaller degrees of aromatic polycondensation and humification. Amendment with SL caused an increase in N, H, S and aliphaticity contents and a decrease in C/N ratios and O and acidic functional group contents in soil HAs isolated 9 months after SL application. These effects tended to decrease after 36 months, most probably because the slightly humified SL-HA was mineralised over time through extended microbial oxidation, while only the most recalcitrant components such as S-containing and aromatic structures were partially accumulated by incorporation into soil HA. Microbial biomass, basal respiration, metabolic quotient and enzymatic activities increased in soil 9 months after SL application, possibly because of increased soil microbial metabolism and enhanced mineralisation processes. After 36 months these properties returned to values similar to those of the unamended soil, presumably due to the loss of energy sources.     

Fire-vegetation interplay in a mosaic structure of Quercus suber woodlands and Mediterranean maquis under recurrent fires

We examined the effects of fire recurrence on a mosaic structure of Quercus suber and Erica-Cistus shrubland communities of Southeastern France in order to improve the understanding of fire-vegetation interplay. Plant communities that were similar in 1959 (woodlands on shrublands called maquis on acidic soils) were compared along a gradient of fire recurrence, from 0 to 4 fires, with different time intervals between fires. The results showed that understory cover increased roughly with fire recurrence, whereas tree height, cover, density, stand basal area and litter depth decreased. Different fire recurrences along the past decades led to different vegetation types. High fire recurrence corresponded to maquis and sparse cork-oak woodlands while pure oak woodlands established in the absence of fire during the same period. In all, the diversity of tree diameter decreased with fire recurrence. High fire recurrence (3 or 4 fires in 50 years) led to a simple vertical structure of vegetation with a mono-layered shrub cover and few Quercus suber trees. In contrast, spatial connections between plants were maximal at longer time intervals, leading to a multi-layered vegetation. We finally discuss the potential implications of past fires on the behavior of future fires in the perspective of a sustainable management of these Mediterranean ecosystems.     

不同固体微生物菌剂对砒砂岩土壤性质和紫花苜蓿生长的影响

为研制改良砒砂岩土壤、强化植物生长的微生物菌剂,该研究以嗜盐芽孢杆菌Bacillus halotolerans P75、苜蓿中华根瘤菌Sinorhizobium meliloti D10、巨大芽孢杆菌Bacillus megaterium H3和枯草芽孢杆菌Bacillus subtilis HB01为原料,利用生物基材吸附混合,制备4种单一固体微生物菌剂和多种复合固体微生物菌剂。通过分析pH值、有机质含量、有效氮磷钾含量、酶活性和细菌数量等指标来研究添加微生物菌剂对砒砂岩土壤性质和紫花苜蓿幼苗生长的影响。结果表明,与不添加微生物菌剂的对照组相比,微生物菌剂能够使砒砂岩土壤pH值降到中性附近,促使土壤有机质、碱解氮、速效磷、速效钾含量显著增加,提高了土壤蔗糖酶和脲酶活性,增加了土壤细菌数量,同时促进了紫花苜蓿幼苗生长,其中以含菌株P75、D10和H3以及含菌株P75、D10、H3和HB01的复合菌剂的效果最佳。该试验研究可以为微生物菌剂在砒砂岩区土壤改良和植被恢复方面的应用提供试验基础和参考。     

早稻施氮对连作晚稻产量和氮肥利用率及土壤有效氮含量的影响

于20022～005年,在湖南长沙采用连续定位试验,研究了早稻施氮对连作晚稻产量、氮肥利用率、土壤有效氮含量的影响。试验设早稻施氮/晚稻不施氮、早稻施氮/晚稻施氮、早稻不施氮/晚稻不施氮、早稻不施氮/晚稻施氮4个处理。结果表明,在连续4年早季施氮的条件下,连作晚稻施氮处理的平均产量为6.45.t/hm2,地上部干物质重12.13.t/hm2,氮素吸收量183.6.kg/hm2,分别比连作晚稻不施氮处理增加28.4%、35.1%和103.5%,均达到显著水平;在连续4年早季不施氮的条件下,连作晚稻施氮处理的平均产量为6.61.t/hm2,地上部干物质重12.14.t/hm2,氮素吸收量165.6.kg/hm2,分别比不施氮处理增加33.4%、37.6%和95.6%,均亦达到显著水平。连作晚稻在早季不施氮和早季施氮两种情况下氮肥利用率不同,前者的氮肥生理利用率显著高于后者,增幅为37.8%,两者的氮肥农学利用效率、吸收利用率差异不显著,但前者4年氮肥农学利用效率平均值比后者高18.1%,吸收利用率低6.8个百分点。早晚两季均不施氮小区土壤碱解氮含量均明显低于其他施氮小区,但没有出现随试验年度加长而连续下降的趋势;当早稻或晚稻其中有一季施用了氮肥,或者两季均施用了氮肥的小区,土壤碱解氮含量差异不显著。说明连作晚稻产量主要受当季施氮量的影响,而受早季施氮量的影响较小;早季不施氮小区的连作晚稻氮肥的农学利用效率、生理利用率比早季施氮小区高;在一定程度上降低稻田氮肥用量不会导致土壤背景氮含量的下降。     

Biogeomorphological influence of the Hawaiian silversword (Argyroxiphium sandwicense DC.) on soil erosion in Haleakala (Maui,Hawai'i)

Soils were examined at 2505 m elevation in Haleakala's crater (Maui, Hawai?i) beneath 50 adult Hawaiian silversword plants (Argyroxiphium sandwicense DC.); mean canopy diameter was 42.0 cm. Exposed volcanic Inceptisols (Andic Humitropepts) seem significantly eroded beyond the dense rosette crowns, but remain unaffected below plants. Rosettes are perched on isolated basal soil mounds or pedestals 27–121 mm high (mean: 77.5 mm). Geomorphic field response of soils below rosettes and adjacent (∼ 100 cm apart) bare soils differs. Infiltration rates are higher under plants (mean: 158.7 mm/min) than in exposed control soils (60.0 mm/min). Soils below silverswords also show greater shear strength (146.1 g/cm²) and compressibility (2.795 kg/cm²) than unprotected soils (36.1 g/cm², and 0.108 kg/cm², respectively). Soil in the plant mounds contains more organic matter; this has influenced other pedological properties, which also differ substantially between sampling positions. Substrate under plants has a porosity ∼ 53% higher than exposed soil, while bulk density is 62% higher in soil outside the plant crown. The observed microtopographic differences are ascribed to greater soil erosion by rainsplash and runoff outside the silversword canopy. The dense rosette crown effectively intercepts raindrops; soils beneath plants also have a high surface cohesiveness provided by a dense network of fine plant rootlets and partially decomposed organic material. Higher runoff rates occur on the less permeable substrate beyond rosettes, which is affected by soil crusting.