Types of Ectomycorrhiza as Pollution Stress Indicators: Case Studies in Slovenia

Mycorrhiza is the main spatial and temporal linkage between different constituents in a forest ecosystem. The functional compatibility and stress tolerance of ectomycorrhizal types is species specific, and therefore the information on the ectomycorrhizal community structure can add to the understanding of processes in forest ecosystems and can also be applied as tools for bioindication of pollution stress in forest soils. We have studied the effects of pollution (N and S) on trees and forest soils by: (1) quantification of ECM types diversity as in situ indicators in forest stands, (2) determination and quantification of pollution-sensitive or -insensitive ECM types as passive monitors, (3) root growth and development of ECM on nonmycorrhizal spruce seedlings, planted at the studied sites (active monitors), and (4) ECM infection (a bioassay based on mycorrhizal inoculum potential) of seedlings in an experimental set-up as ex situ testers. ECM species richness for Norway spruce trees (Picea abies) showed higher values in unpolluted sites than in polluted ones, while the differences were not significant for European beech trees (Fagus sylvatica). As pollution-sensitive or -insensitive ECM species in spruce forests, we suggest Hydnum rufescens (sensitive) and Paxillus involutus (unsensitive). Mycorrhizal potential in Norway spruce seedlings as a bioassay for soil N and S pollution was effective, and is suggested as an additional, standardized and widely comparable system in bioindication of soil pollution.     

A Variance Estimator for Constrained Estimates of Change in Relative Categorical Frequencies

Consistent estimators of change and state becomes an issue when sample data come from a mix of permanent and temporary observation units. A joint maximum likelihood estimator of state and change creates estimates of state that depend on antecedent viz. posterior survey results and may differ from estimates of state derived from a single-date analysis of the sample data. A constrained estimator of change in relative categorical frequencies that eliminates this potential inconsistency is proposed and a model based estimator of their sampling variance is developed. The performance of the constrained estimator is quantified against six criteria and a joint maximum likelihood estimator in simulated sampling from 15 populations with three combinations of permanent and temporary samples, four to six categorical class attributes, and constant size between sampling dates. Bias of the constrained estimators was negligible but larger than for joint maximum likelihood estimators. Mean absolute deviations and variances of constrained estimators were generally at par with the joint estimators. Constrained estimators of root mean square errors and achieved coverage of nominal confidence intervals of constrained estimators were occasionally better. A generalized variance function for the constrained estimates of change is provided as a computational shortcut.     

泥炭保护紫花苜蓿根系对柴油污染土壤修复的研究

采用盆栽试验,观察了泥炭保护根系移栽和直播2种栽培方式处理的紫花苜蓿在柴油污染土壤中的生长情况及其对土壤中柴油污染物的去除情况,探讨了利用泥炭保护根系措施清除土壤柴油污染物的可行性.结果表明,泥炭保护根系处理有利于紫花营蓿根系形态发育,能促进根系细菌和真菌的繁殖,并显著提高根区土壤柴油降解率.     

应用蚕豆根尖微核技术检测淮河水质的研究

本文报道利用蚕豆很尖激核技术研究淮河水的污染情况及致灾变性。结果表明，多数月份该水能诱导蚕豆很尖做校率的明显增高，对综合评价水质提供生物学指标。     

Competition of the active roots of Cassia siamea Lam. and Zea mays L.(cv.Katumani Composite B) in an alley cropping trial in semi arid Kenya

A study on root competition in alley cropping was carried out in an agroforestry system, involving Cassia siamea Lam. and maize ( Zea mays L. cv. Katumani composite B). The existence and intensity of root competition in the top soil as manifested by the distribution of the active roots of cassia and maize, in space and time, was assessed. The root length density of maize was far greater than that of cassia in the upper 10 cm, implying that cassia was not competing with maize for water and/or nutrients at that depth. However, at maize crop tasselling and grain filling stages there was a marked overlap of roots of the two plants at lower depths (20—50 cm). This varied with distance from the cassia hedge in a way that there was a tendency for highest overlap near middle maize rows. This partly explained observed yield differences. Therefore cassia may not be a suitable choice for alley cropping with maize under semi-arid conditions on non-sloping land, unless most of its active roots can be properly managed to absorb resources below the feeding rhizosphere of the active maize roots.     

植物根系对镉毒害的防御及其代谢

本文采用植物根系生物量、根系内活性氧清除酶活性变化和植物表观中毒症状作指标 ,研究了 Cd毒害对草坪植物的毒性作用、根系应激反应。结果表明 ,当土壤溶液中 Cd浓度达 1.5× 10 - 3mol· dm- 3时 ,植物体内活性氧代谢、生长状况将出现异常 ,甚至出现明显的表观中毒症状。 Cd对植物体内清除酶活性的毒性强度为 CAT>SOD>POD。匍匐翦股颖 (Agrostis stolonifera)根系对 Cd毒害的抵抗作用强于多年生黑麦草 (L olium perernne)。     

硝基芳烃化合物诱发细胞微核的比较研究

利用蚕豆根法细胞和人在淋巴细胞的微核试验对６种硝基芳烃化合物的致突变性进行比较研究，结果表明，邻二硝基苯、间二硝基苯、２，４－二硝基甲苯，２，６－二硝基甲苯，对硝基氯苯和对硝基溴苯均能诱发两咱细胞的微核率增加，除了对硝基溴苯外均具有明显剂量一效应关系。引进标准剂量概念比较５种硝基芳烃人合物的致突变性，结果表明，致突变性强弱依次为２，４－二硝基甲苯〉对硝基氯苯〉间二硝基苯〉２，６－二硝基甲苯〉邻二硝     

Using multivariate regression modeling for sampling and predicting chemical characteristics of mixed waste in old landfills

Municipal solid waste landfills pose a threat on environment and human health, especially old landfills which lack facilities for collection and treatment of landfill gas and leachate. Consequently, missing information about emission flows prevent site-specific environmental risk assessments. To overcome this gap, the combination of waste sampling and analysis with statistical modeling is one option for estimating present and future emission potentials. Optimizing the tradeoff between investigation costs and reliable results requires knowledge about both: the number of samples to be taken and variables to be analyzed.This article aims to identify the optimized number of waste samples and variables in order to predict a larger set of variables. Therefore, we introduce a multivariate linear regression model and tested the applicability by usage of two case studies. Landfill A was used to set up and calibrate the model based on 50 waste samples and twelve variables. The calibrated model was applied to Landfill B including 36 waste samples and twelve variables with four predictor variables.The case study results are twofold: first, the reliable and accurate prediction of the twelve variables can be achieved with the knowledge of four predictor variables (Loi, EC, pH and Cl). For the second Landfill B, only ten full measurements would be needed for a reliable prediction of most response variables. The four predictor variables would exhibit comparably low analytical costs in comparison to the full set of measurements. This cost reduction could be used to increase the number of samples yielding an improved understanding of the spatial waste heterogeneity in landfills.Concluding, the future application of the developed model potentially improves the reliability of predicted emission potentials. The model could become a standard screening tool for old landfills if its applicability and reliability would be tested in additional case studies.     

环草隆与重金属复合污染对黄瓜及小麦的毒性效应评估

为探究草坪除草剂与重金属复合污染对高等植物的生态毒性效应,以小麦与黄瓜为敏感受试植物,采用滤纸发芽试验法,研究了典型草坪除草剂环草隆与4种重金属(Cu/Zn/Pb/Cd)单一及复合污染条件下,对2种植物种子萌发与幼苗生长的毒性效应并进行评估。在此基础上采用评估因子法外推环草隆在土壤中的预测无效应浓度(PNECsoil)。结果表明,2种植物的根长及小麦的芽长对环草隆与重金属非常敏感(P<0.01),且存在明显的剂量-效应关系。黄瓜根长对环草隆最敏感,根长半抑制浓度(RI50)为0.281 mg·L-1。小麦根长对Cu、Pb、Cd比黄瓜根长更敏感。环草隆与重金属复合污染时,黄瓜根长表现得最为敏感,可作为敏感生物标记物。环草隆与重金属复合污染对小麦及黄瓜根长抑制具有协同作用,并且随着重金属浓度的增大,黄瓜和小麦根生长对环草隆的敏感性增加。环草隆与重金属复合污染对小麦芽长的联合效应主要与重金属种类及其暴露浓度有关。以黄瓜的根伸长抑制率为急性毒性终点,利用外推法计算得环草隆在土壤中的PNECsoil为1.90μg·kg~(-1),远远低于环草隆田间推荐使用量1.5~9 mg·kg~(-1)。与重金属复合污染时,环草隆的PNECsoil明显降低,导致其生态风险提高。上述研究结果能够为草坪除草剂环草隆与重金属复合污染的生态风险评价提供数据支持。