Bruno Boz

Vegetation, soil and hydrology management influence denitrification activity and the composition of nirK-type denitrifier communities in a newly afforested riparian buffer

Soil microbial community composition and activity could be affected by suitable manipulation of the environment they live in. If correctly applied such an approach could become a very effective way to remediate excess of chemicals. The concentration of nitrogen, especially nitrate deriving from agricultural managements, is generally found to increase in water flow. Therefore, by forcing the water flow through a buffer strip specifically designed and possibly afforested with suitable plant species, may result effective in reducing high nitrogen contents. The management of a riparian buffer may definitely affect the soil microbial activities, including denitrification, as well as the composition of the community. The present study reports on the changes occurred in terms of denitrifying microbial community composition, as compared to that of a neighbouring agricultural area, as a consequence of hydraulic management coupled to the suspension of farming practices and to the development of the woody and herbaceous vegetation. With this aim, denitrification was repeatedly measured and the data obtained were related to those deriving from a specific analysis of bacterial groups involved in denitrification. nirK, encoding for nitrite reductase, an enzyme essential for the conversion of nitrite to nitric oxide and considered the key step in the denitrification process, was chosen as the target gene. The main results obtained indicated that denitrification activity changes in riparian buffer as compared to agricultural soil and it is strongly influenced by carbon availability and soil depth. Although no significant differences on the community composition between superficial (0-15 cm) and medium (40-55 cm) layers were observed, the nirK-type denitrifier community was shown to significantly differ between riparian and agricultural soils in both surface and medium layers.

Bacterial diversity of a wooded riparian strip soil specifically designed for enhancing the denitrification process

This research is part of a project aimed at verifying the potential of a specifically assessed wooded riparian zone in removing the excess of combined nitrogen from the Zero River so as to reduce nutrient inputs into the Venice Lagoon. Among the specific objectives of the project, there was the determination of change in the composition of the microbial populations of soil of the wooded riparian strip. The composition of the bacterial communities collected at different depths inside and outside the riparian strip was determined by combined approaches involving cultivation (CFU), microscopic approaches (CTC test), and DNA-based techniques (ARDRA and DGGE). The size of the living population was the same inside and outside the experimental strip, with a minor percentage of culturable bacteria. Higher numbers of metabolically active bacteria and higher bacterial diversity were detected in the internal soil, with deeper soil layers showing reduced diversity, thus indicating that soil management within the riparian strip effectively supports the viability of bacterial communities. Total operational taxonomic units (OTUs) and percentage of single OTUs were also found to be always higher in the internal soil samples for all soil layers, with the percentage of Firmicutes increasing and Actinobacteria decreasing with depth. The increasing soil organic carbon inputs due to the contribution of the growing plants were found to support bacterial diversity in all soil layers. DNA-based analysis also indicated a clear effect of the applied treatments on soil bacterial diversity and a well-defined separation of the bacterial communities related to the different soil layers of the riparian strip.

The Italian Rivers

Few Italian rivers today can be considered to be in a natural state. Since humans have colonized this region, they have strongly interacted with the rivers and their natural dynamics by shaping their morphology and using the landscape. Exploitation of natural resources has been so extensive that today only small areas of the landscape and of the rivers that flow through it can be considered natural. Italian rivers comprise a diversity of fluvial ecosystems, ranging from Alpine glacier-fed streams to ephemeral Mediterranean streams and from large rivers, such as the Po, to spring-fed brooks and artificial canals. They all flow through densely populated areas. Although Italy is rich in water resources, the distribution is uneven, with the majority occurring in the north (65%), 15% in the centre, 12% in the south, and 8% in the main islands. Because of this variability, this chapter focuses on the Po River, which forms the largest Italian plain and covers ∼24% of Italy. Other Alpine rivers described in the chapter include the Adige, the second longest Italian river, the Tagliamento because of its relatively pristine condition, and the Brenta River because of its historical role in the region and as an example of a river with a mix of natural and regulated reaches.

Monitoring and Modeling Digestate Fate and Transport in Infiltrating Afforested Areas Versus Maize/Ray-Grass Rotation Plots

Managed aquifer recharge systems must account for the expected long-run performance from a water quality viewpoint to be considered sustainable in ameliorating not only the groundwater quantity but also its quality. Gravity-driven infiltration ditches in newly afforested areas are one of many managed aquifer recharge systems that could enhance the availability of groundwater resources in medium and short runs. Although, in highly anthropized landscapes such as in Northern Italy, the need of large areas for managed recharge systems is often controversial with respect to the classical land use, which is prevalently agricultural. For this reason, a large scale field experiment has been conducted recently to assess the potential of combining managed aquifer recharge systems with the need of maintain productive the land (Mastrocicco et al. in Ecohydrology, 9(1):167–178, 2016).

Preliminary assessment on flood mitigation potential via managed aquifer recharge in the Brenta megafan (Italy)

Managed aquifer recharge (MAR) design and operation must incorporate the expected long-term performance from a water quantity perspective to sustainably mitigate hydrologic impacts of groundwater overexploitation. Gravity driven infiltration ditches are one of many MAR schemes that could augment the available water resources. In the present study, an infiltration system (IS) consisting of 8 ditches was monitored to determine its hydrologic performance over time and its possible export to similar areas of the Brenta Megafan (Northern Italy). The IS displayed an almost constant capacity to infiltrate the diverted water with a total amount of 0.8 Mm3/ha/y. The good results suggest to promote this technique in other areas that suffer from groundwater resources depletion