Cristina Muschitiello*, Pasquale Campi, Alejandra Navarro, Marcello Mastrorilli, Rossana M. Ferrara, Gianfranco Rana
Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria (CRA) – Research Unit for Cropping Systems in Dry Environments (SCA), via C. Ulpiani 5, 70125, Bari, Italy
Abstract
Groundwater quality indicators for irrigation of Mediterranean plant species was identified within the project called MONITI (Continuous MONIToring of hydrological trends of groundwater quality parameters for agro-environmental
purposes) afferent to the FESR Apulia Operative Program 2007-2013.
A bibliographic research on national and international journals, integrated with Italian and European laws and regulations, was conducted and both classical water quality indicators (temperature, pH, conductivity and dissolved oxygen) and newer ones (chlorides, nitrates and ammonium) were identified, the latter to be automated on innovative probes. Thresholds for any indicator were defined, differentiated for three different types of crops: food, no-food and urban green. Finally an algorithm was implemented and tested able to indicate the types of crop that can be irrigated with the groundwater as function of the water thresholds previously defined.
Parole chiave
Nitrati, ammonio, cloruri, colture food e no-food, verde urbano
Keywords
Nitrate, Ammonium, Chlorides, food and no-food crops, urban green
Introduction
Groundwater represents the primary source of drinking water in Italian regions and in some cases reaches the 90% of consumes, entailing the need for the implementation of measures of quality control.
Actually, the in situ groundwater monitoring systems detect on-line “classical” parameters such as temperature, dissolved oxygen, pH and electrical conductivity, using multiparametric and thermal-conductometric probes. Other “innovative” parameters, useful to assess the state of water pollution, are already measured in laboratory, but there are not probes for continuosly moniotirng them in the field. For a thorough understanding of the type of pollution that may be present in groundwater, within the project called MONITI (Continuous MONIToring of hydrological trends
of groundwater quality parameters for agro-environmental purposes) afferent to the FESR Apulia Operative Program
2007-2013, chemical and physical measures of quality control were identified that should be monitored continuously together with the parameter traditionally measured. A new monitoring system was assembled that can continuously measure both traditional and new parameters and an algorithm was constructed for on-time identification of the types of crop that can be irrigated with the analysed groundwater.
Materials and Methods
The research and analysis of quality parameters was made on a set of representative Mediterranean common crops, divided into three different quality types: food, no-food and
urban green, including arable crops, vegetable crops, tree crops, cut flowers, flowering plant, shrubbery and trees. Three parameters were chosen to integrate the classical ones used in groundwater quality assessment: chlorides, nitrates and ammonium. Indeed, a high content of chloride would cause an arrest in crops’ development for the phenomena of iron chlorosis, but high content of nitrates and ammonium is good for some crops because it represents a nutrient supply (Giardini, 2012). Anyhow, for some food crops, the administration of nitric and ammoniacal nitrogen above a certain threshold could reduce the quality of the product (Caliandro et al., 2001). Specific thresholds for the seven parameters were identified via a detailed research on national and international books and journal, one for any crop of every group inside each quality type. National and European laws and regulation were, also, consulted, on the one hand in order to ensure that the thresholds found complied with those laws and regulation, on the other hand in order to fill some gaps in the thresholds definition. The first law concerning groundwater quality is the Ministerial Decree 471/1996, replaced in 2006 by Part IV of Title V of Legislative Decree no. 152/2006, known as the Consolidated
environmental script. It establishes the concentrations of
some pollutants in groundwater over which the site is considered potentially contaminated. Unfortunately none of the two Decrees is exhaustive in terms of both pollutant elements and definition of thresholds for specific plant species. For this reason also the Legislative Decree 185/2003 concerning wastewater reuse in agriculture was
consulted and considered for filling the thresholds of parameters for all the selected crops.
Finally, an algorithm was created and implemented with R (http://www.R-project.org) that on-time identifies the types of crop that can be irrigated with the analysed groundwater at a given time. The algorithm was trained with the groundwater thresholds previously defined and it was tested via the simulation of groundwater data based on ranges of plausible values for each parameter found in literature and on random dates of years from 2004 to 2010.
Results and Discussion
A general table containing thresholds for each parameter and for any crop’s quality type was created. This table also contains the reference indicating where the specific threshold was found and contains the indication “Different threshold for different crops” in all those cases in which thresholds were defined for each crop selected in the pattern of Meriterranean plant species. The general table is reported in Tab.1, while as example the detailed table for Conductivity thresholds in Urban green colture’s quality type is reported in Tab.2.
Tab.1 – General table of thresholds and references for parameters and colture’s quality type.
Tab.1 – Tabella generale delle soglie e riferimenti bibliografici per ciascun parametro diviso per tipo di qualità delle colture.
Parameter Unit Severity
thresh. Limitatio n thresh. Attention thresh. Severity thresh. Limitatio n thresh. Attention thresh. Severity thresh. Limitatio n thresh. Attention thresh. Temperature °C < 4,5 > 8,5 < 5,5 < 6,5 < 4,5 > 8,5 < 5,5 < 6,5 < 4,5 > 8,5 < 5,5 < 6,5 Conductivity dS/m Dissolved Oxygen (BOD5)mg/l-1 Chlorides ppm Nitrates mg/l Ammonium mg/l 2 (D.Lgs. 152/2006) 3 (Caliandro et al., 2001) 250 (D.Lgs 185/2003) 20 (D.Lgs 185/2003) Different thresholds for
different crops 250 (D.Lgs 185/2003) 250 (D.Lgs 185/2003) pH pH (Giardini, 2002)
<50 Class I: water use with no limitation >50 Class II: water use with agronomic limitations
(Caliandro et al., 2001) Different thresholds for
different crops
Different thresholds for different crops
Different thresholds for different crops >= 2/3 Air temperature (Giardini, 2002) Parameters (importance order) Thresholds for Food crops Thresholds for No-Food crops Thresholds for urban green crops
Tab.2 – Thresholds for conductivity (dS/m) for the "urban green" colture’s quality type.
Tab.2 – Soglie di conducibilità elettrica (dS/m) per colture di tipo “verde urbano”.
Group Plant Species dS/m Ref.
Fraxinus pennsylvanica var. lanceolata 2,1 Quist et al., 1999 Rosmarinus ojjicinalis 5,4 Niu et al., 2007 Nerium oleander 8 Miyamoteo, 2008 Pinus halepensis 1,87 Jordan et al., 2001 Pinus pinea 1,87 Jordan et al., 2001 Robinia xambigua 1,87 Jordan et al., 2001 Ulmus parvijolia 1,87 Jordan et al., 2001 Pistacia chinensis 1,87 Jordan et al., 2001 Shrubbery
Trees
In the general table the seven parameters are included in their importance order, meaning that when a groundwater sample is analyzed these parameters have to be tested in the
order they are reported and if the sample does not pass one of the test it will considered unsuitable for irrigation. This logic was used in the algorithm implementation. Indeed, it tests any parameter in succession and stops when one parameter’s value is over its thresholds, also returning an error message. For testing the groundwater temperature, time series of air temperature for the target area of the MONITI Program were used. Figure 1 reports the algorithm’s output for a case of a sample with a pH value under the limitation threshold of use.
Fig.1 – Sample Output of the Algorithm for groundwater quality definition for irrigation use.
Fig.1- Output di esempio dell’algoritmo di definizione di qualità delle acque sotterranee per fini irrigui.
Conclusions
Groundwater quality parameter’s set defined within the MONITI program aims to be a new set of parameters whose sensors might be installed on a new generation of multiparameter probes together with an on-time software based on algorithms of the kind created and presented in this paper. Prototype creation and some test sessions have already been conducted within the cited program and, even if conspicuous data sets still have to be obtained and validated, the analysis made can be considered as a starting point for the construction of a new valid instrument for data gathering and administration. Indeed it can make possible a timely control of groundwater highlighting contamination phenomena and quickly allowing any immediate actions.
Bibliography
Caliandro A., Molinari G., Luca Fornara L., Mecella G., 2001. Qualità delle acque per uso irriguo. Metodi di di analisi delle acque per uso agricolo e zotecnico: pag.11-31. Giardini L., 2012. L’Agronomia. Per conservare il futuro. Patron Editore, Bologna, pp. 704.
Jordan L.A., Devitt D.A., Morris R.L. and Neuman, D.S., 2001. Foliar damage to ornamental trees sprinkler-irrigated with reuse water, Irrigation Science 21: pag.17-25.
Miyamoto S., 2008. Salt Tolerance of Landscape Plants Common to the Southwest. Texas Water Resource Institute and El Paso Water Utilities, El Paso (TX), pp 37.
Niu G., Rodriguez D.S. and Aguiniga L., 2007. Growth and landscape performance of ten herbaceous species in response to saline water irrigation. ]ournal oj Environmental Horticulture 25: pag 204-210.
Quist T.M., Williams C.F. and Robinson, M.L.,1999. Effects of varying water quality on growth and appearance of landscape plants. Journal of Environmental Horticulture 17: pag. 88-91.