Monitoring the environmental impact of anthropogenic disturbance on soil ecosystem is of great importance for optimizing strategiesfor soil use, conservation and remediation. The aim of this study was to assess whether and to what extent a long-term, human-induceddisturbance could have affected main chemical and biological properties in an agricultural soil. The study site was a hazel (Corylusavellana L.) orchard located in the area surrounding the volcanic apparatus of Somma-Vesuvius (Southern Italy). For the last twodecades, the site has been repeatedly subjected to floodings by wastewaters containing not only alluvial sediments but also potentiallyhazardous compounds from illegally disposed wastes. Soil disturbance was assessed by a multitechnique approach, which combinedchemical, biochemical and physiological (Biologs) methods together with community fingerprinting by denaturing gradient gelelectrophoresis (DGGE) and amplified ribosomal DNA restriction analysis (ARDRA). A hazel site never subjected to flooding providedthe control soil. Soil sampling was repeated three times over a 1-year period. The effect of flooding by wastewaters, sampling time andtheir interaction were statistically evaluated. Under wastewater flooding, soil pH and most organic matter-related pools, i.e. total organicC, total N, and active soil C-resources such as basal (SBR) and substrate-induced respiration (SIR) and microbial biomass C (MBC)were all increased; whereas sampling time mostly affected two active-N pools, namely K2SO4-extractable N (Extr-N) and potentiallymineralizable N that varied unconcurrently in tested soils. Also the electrical conductivity varied across samplings. Parameters related tomicrobial maintenance energy (ATP and qCO2) were higher in the flooded soil, even though they were not statistically affected bywastewater flooding or by sampling time. The Biologs method evidenced that under recurrent flooding, soil microbial populationsbecame functionally more uniform when compared to the control soil. Molecular fingerprinting of PCR-amplified 16S rDNA targetsrevealed that, along with seasonal shifts, a marked change in the genetic structure of total bacterial community occurred in the floodedsoil. Furthermore, compositional shifts in the actinomycete community were less marked and mostly influenced by seasonal effects. Yet,a decreased genetic diversity in the ammonia-oxidizing bacteria community was evidenced in the flooded soil by ARDRA. Thus both thegenetic and the functional structure of native soil bacterial populations were changed under repeated flooding by wastewaters. Repeatedsampling over a 1-year period allowed us to reveal soil disturbance effects beyond seasonal variations.
|Numero di pagine||12|
|Rivista||SOIL BIOLOGY & BIOCHEMISTRY|
|Stato di pubblicazione||Published - 2006|
All Science Journal Classification (ASJC) codes
- Soil Science