Phospholipid fatty acid (PLFA) analysis has gained great importance in the study of soil microbial community structure. This structure can give indication of the soil status. Purpose of the present paper is to analyse PLFA patterns in altered agricultural soils in order to develop a soil status alteration index. Soils subjected either to intensive agricultural exploitation, or to overflow by municipal and industrial wastes, or to irrigation with saline waters were analysed for PLFA content and compared to adjacent untreated soils by means of different statistical techniques.
Principal component analysis separated PLFAs in three groups: unsaturated PLFAs (first axis, 48% of total variance), monounsaturated and cyclopropane PLFAs (second axis, 28% of total variance) and polyunsaturated PLFAs (third axis, 24% of total variance).
By means of canonical discriminant analysis, a soil alteration index (SAI) was produced from 15 PLFAs using two data sets. A third data set was used to test the SAI general validity together with other data sets reported in literature. The index validity was confirmed in most cases: SAI gave higher scores for control soils and was generally able to classify soils according to their reported degree of alteration. 相似文献
The concentrations of semi-volatile polycyclic aromatic hydrocarbons (PAHs), hydrocarbons (HCs), particulate matter (PM 1, 2.5 and 10 μm) and total suspended particles (TSPs) were measured in a traffic tunnel in Gothenburg, Sweden. Emission factors (EFs) were also calculated. These variables are assumed to provide good estimates of average vehicle emissions, since all types of vehicle, using all types of fuel, pass through this tunnel. It was shown that the majority of particle-associated PAHs were found on particles with an aerodynamic diameter of <1 μm. The concentrations of PAHs were one order higher in magnitude in air samples from the tunnel than in air samples at two urban locations. However, the PAH profiles of air samples from the tunnel and the urban sites were similar. This was demonstrated using principal component analysis (PCA). Finally, and notably, there was no significant change in the total emissions when the proportion of heavy-duty vehicles (HDVs) increased from 8% to 24%. Previously, diesel vehicles had been found to release larger quantities of PAHs and related substances. Advances in fuel quality, and HDV motor and exhaust system design during the last decade may have contributed to this promising result. However, it was shown, using partial least squares regression to latent structures (PLS), that some of the parameters measured displayed correlations with the proportions of HDVs and light-duty vehicles (LDVs). Concentrations of total HCs, TSPs, dibenzothiopene, phenantrene, anthracene and monomethyl-derivatives of phenantrene and anthracene were all correlated to the proportion of HDVs. The concentrations of naphthalene, some mono- and dimethylnaphthalenes and most large PAHs (with 5–7 fused rings) were correlated to the proportion of LDVs. 相似文献