Latest Trends in Engineering Mechanics, Structures, Engineering Geology Using Artificial DNA as tracer in a bedrock river of the Middle Bussento Karst System (Cilento, Vallo Diano and Alburni European&Global Geopark, southern Italy) VITTORIO BOVOLIN, ALBINA CUOMO, DOMENICO GUIDA Department of Civil Engineering University of Salerno Via Giovanni Paolo II ITALY [email protected] JAN WILLEM FOPPEN Institute of Water Education Unesco-IHE Delft THE NETHERLAND Abstract: The paper deals with strengths and shortcomings of the use of artificial DNA as tracer in environments as such the fast flowing water in bedrock and step-and-pool streams. The use of synthetic DNA as tracer has been tested in rivers and brooks, and in carbonate rocks, but no attempt has been made, so far, to use this technique in torrents and ground water. One of the main strength is the low environmental impact which makes its use very appealing in protected areas. Taking into account these considerations an artificial DNA test was carried out in a fast flowing reach of the Middle Bussento Karst System. The artificial DNA technique was performed together with a traditional salt injection test. Results obtained from the experiment confirm the overall effectiveness of the use of artificial DNA in fast flowing environment, particularly excellent is the DNA mass conservation compared to the salt test. The main shortcoming of the artificial DNA test resides in the elaborate sampling procedure which requires the approximate knowledge of the transit time of the water into the system. Key-Words: Karst, artificial DNA, tracer, Bussento river, National Park of the Cilento, Vallo Diano and Alburni-European&Global Geopark, southern Italy. 1 Introduction The level of complexity of such systems is dictated Environment protection and proper water resource by the geological litho-structures and hydro- assessment and management require a good geomorphic processes which have shaped both the knowledge of catchment basin structure and surface and the underground portion of the karst functioning [9]. This knowledge have to be acquired landscape. Understanding relationships existing by interdisciplinary studies regarding hydro- between these two “worlds” is paramount. This is geological setting, hydrological recharge-discharge particularly true for Mediterranean protected areas, monitoring and hydraulic modelling [3]. This is as such the Cilento, Vallo Diano and Alburni particularly important in the case of complex National Park (in the following National Park), situations, such as aquifers-rivers interaction in located in the southern of Italy, where the water mature karst-influenced hydro-systems [3]. Water quality must be kept at the highest standard in order resources from karst systems not only are one of the to ensure healthy populations of fishes and aquatic primary sources of drinking water in many areas, fauna (native trout, otter, fresh water crayfish, and but there is an increasingly recognition of the others). Monitoring and modeling of the riverine importance of assuring their quality as they eco-system has been carried in the past by the represents the basic abiotic support for all riverine University of Salerno and CUGRI [11] in habitats and fluvial ecosystems. cooperation with the Basin Authority and the ISBN: 978-960-474-376-6 105 Latest Trends in Engineering Mechanics, Structures, Engineering Geology National Park, whose are in charge of water The aim of the test was to explore potentials and planning and management in the protected area [9]. shortcomings of the use of artificial DNA tracer in environments as such fast flowing water in bedrock Recently, the inclusion of the National Park into the and step-and-pool streams. European and European & Global Geopark Network, under the auspices of the UNESCO, has fostered further research agreements focused on 2 Hydro-geomorphological setting water research with international organizations [9]. One of the aim of these collaborations is to develop The Bussento river basin, located in the Campania new monitoring techniques that may overcome Region, is one of the more complex drainage river limitations of traditional ones and allow monitoring systems in Italy (Fig. 1). activities in sensitive environments [5]. In the National Park, the Bussento river basin has been identified as an appropriate playground for testing new techniques. Monitoring activity in this area is a challenging task both for the complexity of the system and for the strict regulation which set tight constrains to the use of traditional monitoring techniques. Tracer testing is an efficient and useful method to characterize hydrological processes both in surface and subsurface waters [10]. The use of synthetic DNA (deoxyribonucleic acid) as tracer is a relatively new technique [4], whose use can be performed with a, theoretically, unlimited number of tracers. Tracer testing with synthetic DNA experiments has been tested in rivers and brooks, [5] e [6], and in calcareous rock [2]. So far no attempt has been Fig. 1: Location of the Bussento river basin in the Cilento, Vallo made to use such technique in torrents and ground Diano and Alburni National Park – European and Global water included in protected areas. One of the main Geopark. interests in this technique, beside the reduced environmental impact [5], resides into the The complexity is due to the highly hydro- possibility of using, in the future, different multiple, geomorphological conditioning induced by karst synthetic DNA tracers at the same time [5]. This landforms and processes as such as: karst highlands would be particularly useful in cases, as such the with dolines and poljes, lowlands with blind valleys, Bussento karst-influenced river, where it is known streams disappearing into sinks, cave systems, karst- that many stream sinks converge in the same outlet induced groundwater aquifers with resurgences. [9] and bed stream seepage induces discharge losses The Bussento river originates from the upland along the river reach. In these cases, traditional springs of Mt. Cervati (1,888 m asl), one of the techniques do not allow to distinguish contribution highest mountain in the southern Apennines. coming from each stream sink as well as investigate the gaining-losing processes along the river reach. The Upper Bussento flows partly in wide alluvial The artificial DNA technique may, at least in valleys (i.e. Sanza valley) and partly along steep principle, mark each inlet or loss with a different gorges and rapids. Along this path, abundant artificial DNA signature and allow to identify its springs, emerging from karst aquifers, deliver fresh individual and distinctive contribution. Therefore, in water into the streambed, increasing progressively order to test the feasibility of this technique in a the river discharge. Near Caselle in Pittari the main karst environment, an artificial DNA tracer test was river and some adjacent minor creeks flow into three carried out in the Middle Bussento Karst System active stream sink, named La Rupe, Orsivacca and (MBSKS). Bacuta-Caravo, respectively. ISBN: 978-960-474-376-6 106 Latest Trends in Engineering Mechanics, Structures, Engineering Geology These geosites are recognized as “principal reach represent one of more relevant ecological geosites” in [1]. The cumulative river discharge is habitats in the National Park, hosting many conveyed into a converging hypo-karst cave system populations of fishes and aquatic fauna (native trout, and, after a path of few kilometers, re-emerges in otter, fresh water crayfish, river lamprey). For this the “Bussento Resurgence”, which is a “focal ecological relevance the site is currently a WWF geosite” in [1]. The underground karst system is Oasis. largely unknown since only few hundred meters downstream the sinkholes and upstream the resurgence (Fig. 2) have been explored. 3 Experiment layout and procedure On April the 10th 2012, a coupled salt and artificial DNA tracer test was carried out in the MBSKS: the activities were carried out by the IHE-Unesco researchers (Delft, the Nederlands) in collaboration with researchers of CUGRI-Salerno University, supported financially and professionally by the National Park and the Southern Campania Regional Basin Authority. The experiment was conceived according to a two- step procedure: in the first step a known, little amount of salt was injected at the upstream section of the test site (Fig. 3), then the hydro-chemograph behavior of the flowing water at the downstream section was monitored. This step was aimed to detect the salt transit times in to the system so to provide useful information for the implementation of the second step which involved the injection of the artificial DNA. Fig. 2: Hydro-geomorphological map of the MBSKS. The location chosen for the test was the torrent Legend: gsl. gravelly sandy silty complex; dt. debris reach (Fig. 3) from the Old Mill spring outlet (Fig. complex; Ar: Sandstone Complex, corresponding to the 4) to a section located immediately upstream the Internal Units; Am: Marly-clayey complex, comprising junction between the Old Mill reach and the BfFrm and PgFrm; Cm: Marly limestone complex, Resurgence reach (Fig. 5). corresponding to above TFrm; C. Limestone complex, comprising CclL, RqL and RdL formations. Stars: Active sinkholes and stream sinks; Double circle: Arrows: Middle Pleistocene Bussento river path; Buried and fossil stream sink; Double dashed line: Middle Pleistocene Bussento river path ; White portal: Middle Pleistocene Bussento; Black circle: explored underground karst cave system; White dotted circle: un-explored underground karst cave system; Portal: Resourgence; Drop: karst spring; dot-dashed double line: “Le Valli” Sakung; blue arrows: more probable direction of groundwater flow. Upstream and downstream the Bussento Resurgence, the Bussento river flows partly as bedrock and partly as a boulder step-and-pool stream type [11]. This river reach, which is known as the “Morigerati gorge”, is a typical epigenetic valley, where groundwater outflows from epikarst Fig. 3 Hydro-geomorfological sketch of the river reach DNA test site. For legend, see Fig. 2. springs, conduit springs and cave springs supply a perennial stream flow (Fig.