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Volume 6, Issue 6 (Suppl)
J Geol Geophys, an open access journal
ISSN: 2381-8719
Soil Science 2017
December 04-05 2017
Page 32
conference
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December 04-05, 2017 | Madrid, Spain
Annual Congress on
SOIL SCIENCES
Bodoque J M, J Geol Geophys 2017, 6:6(Suppl)
DOI: 10.4172/2381-8719-C1-013
Restoring hydromorphological functionality to improve natural purification capacity of a heavily
modified water body
W
e determined the natural purification ability of a floodplain where irrigated agriculture is a dominant and hydraulic
connectionwith theassociatedriver is limited.Denitrificationactivitywas characterizedbyusingdifferentmethodological
approaches based on i) End-Members Mixing Analysis; ii) characterization of macroinvertebrates of the hyporheic zone;
iii) analysis of the denitrification potential; iv) analysis of the bacterial community structure; and v) hydrologic modeling.
All the approaches, except EMMA analysis, lead to the same conclusion. Denitrification is almost non-existent because the
study site does not have the hydric soil and oxygen-limited conditions needed to enable denitrification. Invertebrates did not
show statistically significant differences (P-value higher than 0.05) between the diversity indices corresponding to each of the
sampling campaigns. However, significant differences (P-value less than 0.01) were found between the piezometers closest to
the river banks and the rest; this may be interpreted because of low hydraulic connectivity. Denitrification potential did not
show significant statistical differences (P-value less than 0.01) between the sampling campaigns conducted. This shows that
besides the absence of connectivity, irrigation is not able to significantly activate denitrification. Additionally, results from the
characterization of the bacterial community structure are consistent with floodplains where denitrification is not effective since
most bacterial communities are not linked with NO3. Hydrologic modeling showed that decay change is very low, on the order
of 0.01 mgN/L.day, although it would improve around 10% if ordinary floods occur. During the summer months theoretical
concentrations of nitrates were lower than expected (e.g. ΔNO3 = - 41 in August 2013), according to the EMMA analysis,
which might be due to the intensity of irrigation is spatiotemporally variable in the study site. Our results show that floodplain
denitrification has been drastically reduced due to the suppression of flood-pulses. In this context, the creation of riverine
wetlands where the hydrological regime is restored would lead to a decay of nitrates whose dynamic evolution increases with
flooding, as scenarios tested by hydrological modeling have demonstrated.
Bodoque J M
University of Castilla-La Mancha, Spain