Vincenzo Tamburino

Relating caesium-137 and soil loss from cultivated land

Abstract Because of the limitations associated with traditional methods of measuring rates of soil erosion, such as erosion plots, the fallout radionuclide caesium-137 (137Cs) has been increasingly used in recent years as an alternative approach to estimating rates of soil redistribution on both cultivated and noncultivated areas. The successful application of the 137Cs approach depends heavily on the availability of reliable conversion models for converting measurements of 137Cs redistribution, relative to the local reference inventory, to estimates of soil redistribution rates. In the absence of empirical conversion models, most studies have made use of theoretical conversion models. The assumptions made by such theoretical models are frequently untested and they thus remain largely unvalidated. This contribution describes the results of a measurement programme involving nine experimental plots located in southern Italy, aimed at validating several of the basic assumptions commonly associated with the use of mass balance models for estimating rates of soil redistribution on cultivated land from 137Cs measurements. Overall, the results confirm the general validity of these assumptions. However, several other assumptions and process representations incorporated into such models still require testing and elucidation.

Evaluation and modeling of scouring and sedimentation around check dams in a Mediterranean torrent in Calabria, Italy

The effectiveness of check dams on channel morphology of managed torrents is rarely assessed. Therefore, there is a need for studies that focus on the impacts of existing engineering check dams on the planoaltimetric characteristics of the torrent, particularly in Mediterranean areas, where the hydrological regime of ephemeral channels is dynamically unsteady. The quantitative evaluation of the effects of the check dams on channel morphology after many years (i.e., at least four or five decades) helps introduce innovations to the usual analysis of check dam efficacy which have often been limited to qualitative observations for only a few years after installation. As a contribution to make up these shortcomings, this paper investigates the geomorphologic asset of a torrent in southern Italy containing 10 check dams (installed in the 1950s to 1960s) and analyzes the dynamics of the scouring and sedimentation processes upstream and downstream of selected check dams after 8 rainfall events; moreover, the capability of the model by Castillo (2007) to predict scouring/sedimentation in proximity to these check dams is assessed. Sediment stored upstream of each check dam (where lower channel gradients and wider channel sections formed very long and wide sedimentary wedges) is more than one order of magnitude higher compared to scouring downstream. The morphological analysis revealed that the check dams installed in the headwater reach play a function of bed stabilization (due to the longitudinal slope reduction) and flood lamination (because of the wider channel section) rather than a role of sediment collectors as their sediment storage capacity has already been completed. Scouring/sedimentation dynamics depend mainly on the channel slope and width in proximity to the check dams rather than on structure height. Finally, Castillos model showed an acceptable performance in predicting scouring/sedimentation in the channel bed close to check dams after the monitored rainfall events, the model efficiency being satisfactory and the differences between the mean observed and simulated values low. This investigation improves the understanding about morphological effects of check dams in Mediterranean torrents based on field observations and quantitative analysis.

Storage and Land Application of Olive Oil Mill Wastewater: experiences in Calabria

In the Mediterranean basin about 3x107 m3 of olive oil mill wastewater is produced each season. The high organic matter content of the wastewater, the presence of inhibiting substances, the seasonality of the oil extraction process and the wide geographical dispersion of mills pose considerable technical-economic difficulties for effluent disposal, also in relation to the ever-growing concern over the prevention of water pollution. The experience with current technology for olive oil mill effluent treatment and disposal induces to look for alternative systems for wastewater management. Especially in particular situations (such as those of small oil mills located in rural areas), wastewater application to soil by means of storage-irrigation systems could represent the most efficient disposal solution from the economic and environmental point of view, because it is able to valorize the natural effect of degradation performed by the soil avoiding the pollution of water bodies due to the uncontrolled discharge of untreated effluents. The results of tests in Mediterranean conditions have highlighted that the storage of oil mill wastewater, besides providing the spreading system with an useful flexibility, can also play, in the medium term, a function of effluent pretreatment. The preliminary results of the analysis of soil characteristics, after the application of wastewater volumes much higher than Italian legislation standards, have not highlighted significant problems of degradation.

Depuration in aerated ponds of citrus processing wastewater with a high concentration of essential oils

Citrus processing wastewater was treated in aerated pilot plants in order to evaluate the following: (a) energy efficiency under different air flow rates and times; and (b) limits of spontaneous microflora in adapting to essential oils. In comparison to permanent air flow, night aeration for 12 hours determined an increase of up to 12% of the monthly removal rate of chemical oxygen demand (COD) and a consequent reduction by 10% of energy consumptions per unit of COD removed from 0.63 to 0.57 kWh/kgCOD. Lowering night aeration from 14 to 7 l/m3/h reduced by only 10% the removal rate of COD; the energy consumption per unit of COD removed (0.32 kWh/kgCOD) was consequently reduced by more than 40%. Dissolved oxygen was maintained at very low level, rarely exceeding 0.2 ppm, with no bad smell. The consequent high oxygen deficit of 98–99% of saturation induced high oxygen transfer efficiency. The microbial population was characterized mainly by aerobic bacteria; only 5–8% of bacteria were strictly anaerobic. In the deep tank layer under the air diffuser a small amount of sludge settled (0.03–0.04 kg of dry matter per kg of COD removed), containing only 3% of total organic matter detected at the end of the depuration process. The fact that the concentration of essential oils could be progressively increased up to 1400 ppm without noticeably slowing down the biological processes demonstrated the remarkable microbial adaptation.

Adjustments in channel morphology due to land‐use changes and check dam installation in mountain torrents of Calabria (southern Italy)

In Mediterranean semi-arid conditions, the availability of studies monitoring channel adjustments as a response to reforestation and check dams over representative observation periods, could help develop new management strategies. This investigation is an integrated approach assessing the adjustments of channel morphology in a typical torrent of southern Italy after land-use changes and check dam construction across a period of about 60 years. A statistical analysis of historical rainfall records, an analysis of land-use changes in the catchment area and a geomorphological mapping of channel adjustments were carried out and combined with field surveys of bed surface grain-size over a 5-km reach including 14 check dams. The analysis of the historical rainfall records showed a slight decrease in the amount and erosivity of precipitation. Mapping of land-use changes highlighted a general increase of vegetal coverage on the slopes adjacent to the monitored reaches. Together with the check dam network installation, this increase could have induced a reduction in water and sediment supply. The different erosional and depositional forms and adjustments showed a general narrowing between consecutive check dams together with local modifications detected upstream (bed aggradation and cross-section expansion together with low-flow realignments) and downstream (local incision) of the installed check dams. Changes in the torrent bends were also detected as a response to erosional and depositional processes with different intensities. The study highlighted: the efficiency of check dams against the disrupting power of intense floods by stabilizing the active channel and the influence of reforestation in increasing hillslope protection from erosion and disconnectivity of water and sediment flows towards the active channel. Only slight management interventions (for instance, the conversion of the existing check dams into open structures) are suggested, in order to mobilize the residual sediment avoiding further generalized incision of the active channel and coast line erosion. Copyright

Hydrological Effects of Different Soil Management Practices in Mediterranean Areas

In Mediterranean environment intensive agricultural activities are often practiced in steep slopes, where sometimes climatic, geomorphologic and land use factors (e.g. the high rainfall intensity, the scarce vegetal coverage, especially on the occasion of the early rainfalls, the low organic matter content of soils, etc.) worsen the impacts of soil erosion. In such contexts agriculture may play an important role both in terms of economic and social spin-offs (e.g. peopling of hilly marginal lands) as well as under the environmental aspect (e.g. control of erosion phenomena). This is the case of olive growing practiced in hilly lands with a low tree density (e.g. in Southern Italy), often subjected to torrential rainstorms. Therefore, soil degradation problems in such agricultural steep lands under semi-arid conditions must be accounted for through proper soil management systems with low environmental impacts (mainly on soil hydrology). Until recently, the most common practice for soil conservation in many Mediterranean regions, as Andalusia (Spain, Gomez et al., 2003) and Sicily or Calabria (Italy) has been tillage: however, the tradition of frequent tillage, aimed at preventing competition from natural vegetation for water and nutrients with the olive tree and at facilitating olive harvesting, has exacerbated the problems of erosion and soil degradation (Gomez et al., 2009a). Alternative practices to tillage include: no-tillage with herbicides to maintain a bare and weed-free soil (which sometimes results in accelerated soil erosion due to an increase in water runoff) or the use of a cover crop to protect the soil during autumn and winter, either sown in early autumn or from the regeneration of the natural vegetation after the onset of rains (Gomez et al., 2009a, 2009c). The cover crop is controlled by mowing or by herbicide in spring to reduce the risk of competition for water with the trees, which represents the main limiting factor for plant growth in semi-arid lands, where the evapo-transpiration rate is very high and water resource is scarce. Studies on soil erosion in orchards in Mediterranean environment have analyzed the hydrological effects of the traditional different managements systems (e.g. Dastgheib & Frampton, 2000; Gago et al., 2007; Gomez et al., 2003, 2009b, 2009c; Monteiro & Moreira, 2004); the important role for soil conservation played by the crop cover has been also

Land spreading of solar-dried citrus peel to control runoff and soil erosion.

Marginal areas of southern Italy are often characterised by steep slopes and scarce vegetal coverage, which induce relevant runoff and soil erosion phenomena. On the other hand, the agricultural system of some Italian regions is characterized by the presence of many citrus industries, producing high amounts of by-products and wastewater. The possibility of spreading orange peel over land could represent an alternative solution for a more sustainable biomass disposal and, at the same time, protect against the risks soil erosion in Mediterranean areas. This paper reports the results of an experimental research activity aimed at evaluating the hydrological effects of land spreading of solar-dried citrus peel over steep plots (remodelled at 100%-slope), containing bare soil or covered by vegetation and exposed to natural rainfalls. The comparison of hydrological observations to those performed on untreated soils (“control”) highlighted that the addition of citrus peel to soil induced an appreciable reduction of runoff and particularly of sediment yield, due to the improvement of the soil properties, which encourages the establishment and development of vegetation.

Crop and management factor estimate for applying RUSLE in rangeland areas

The Revised Universal Soil Loss Equation (RUSLE) is a relatively simple model for estimating soil losses in agricultural lands and its use is attracting increasing attention around the world. Although all the factors in this model are receiving close attention and research is continuing to refine and improve the knowledge of how each factor affects erosion, much of research focus on the crop and management factor (C). Studies on the C-factor are continuing, not just for cropland where much of the research is occurring, but also for other agricultural land uses such as pasture, rangeland and forestland. In this paper, the results of a research involving 9 experimental plots located in Southern Italy aimed at validating some of the assumptions associated with the estimate of C-factor for rangeland conditions, are reported. The experiment involved rainfall, runoff and soil loss measurements for a three-year period which were used to evaluate the crop and management factor for perennial plants. Then, a simple procedure involving biomass seasonal measurements for evaluating the C-factor is proposed. The RUSLE model coupled with this empirical procedure showed good agreement between measured and calculated soil losses. Finally, in order to represent the model limitations and uncertainties, the effect of parameter uncertainty was studied by Monte Carlo method.

Wastewater irrigation. lysimeter investigation on water quality aspects.

Abstract A lysimeter investigation has been carried out with the aim of quantifying the removal of some contaminants during wastewater percolation through the soil. The lysimeters were irrigated with untreated municipal wastewater. In general volcanic sand showed higher treatment ability than sedimentary soil. Percolation through sandy volcanic soil columns resulted in removal of 84 to 98% of applied COD and of 90 to 96% of applied suspended solids.

Valorisation of citrus processing waste: A review

This study analyses the quantitative and qualitative characteristics of citrus peel waste and discusses the systems for its valorisation. Citrus peel waste (CPW) is the main residue of the citrus processing industries and is characterised by a seasonal production (which often requires biomass storage) as well as high water content and concentration of essential oils. The disposal of CPW has considerable constraints due to both economic and environmental factors. Currently this residue is mainly used as food for animals, thanks to its nutritional capacity. If enough agricultural land is available close to the processing industries, the use of CPW as organic soil conditioner or as substrate for compost production is also possible, thus improving the organic matter content of the soil. Recently, the possibility of its valorisation for biomethane or bioethanol production has been evaluated by several studies, but currently more research is needed to overcome the toxic effects of the essential oils on the microbial community. Considering the high added value of the compounds that can be recovered from CPW, it has promising potential uses: in the food industry (for production of pectin, dietary fibres, etc.), and in the cosmetic and pharmaceutic industries (extraction of flavonoids, flavouring agents and citric acid). However, in many cases, these uses are still not economically sustainable.