*3.2.3 Analysis by land use*

To assess the variability of nitrate atmospheric deposition fluxes by land use, sampling sites were grouped according to the prevailing land use as follows:

**53**

**Figure 7.**

*Mapping and Estimation of Nitrogen and Sulfur Atmospheric Deposition Fluxes…*

year<sup>−</sup><sup>1</sup>

year<sup>−</sup><sup>1</sup>

year<sup>−</sup><sup>1</sup>

In the case of sites grouped with an urban land use, it was obtained a mean value

, with a maximum of 3.26 Kg Ha<sup>−</sup><sup>1</sup>

with a maximum value of 15.78 Kg Ha<sup>−</sup><sup>1</sup>

with a maximum of 6.07 Kg Ha<sup>−</sup><sup>1</sup>

values, the highest nitrate deposition fluxes were found in site X (**Figure 7**). On the other hand, in the case of sites grouped with an industrial land use, the mean value

highest flux was registered in site I, corresponding to monitoring station located at

From **Figure 8**, it can be observed that the mean ammonium deposition flux was higher during the cold dry season. During the cold dry season, the mean value

which corresponds to sites I and IV (CICEG Bomberos and Instituto Tecnológico de León, located at SE). On the other hand, during the other two seasons, nitrate deposition fluxes were significantly lower. The mean value obtained during warm

VI (Zoológico located at NE), whereas the mean value registered for rainy season

The marked seasonality found in ammonium levels suggests two important aspects: first, the dilution effect is important since ammonium levels during the rainy season were considerably lower as a result of frequent and intense rains

with a maximum value of 1.06 Kg Ha<sup>−</sup><sup>1</sup>

in sites with an urban land use; this agrees with the origin of nitrate, whose main source is mobile sources, which are uniformly distributed along metropolitan area of León. This hypothesis was confirmed by applying Friedman tests which demonstrated

that there were not significant differences between sampling sites or land use.

According to **Figure 7**, it can be observed that nitrate deposition was slightly higher

year<sup>−</sup><sup>1</sup>

. Regarding extreme

. The

year<sup>−</sup><sup>1</sup>

in site

year<sup>−</sup><sup>1</sup>

in site III

year<sup>−</sup><sup>1</sup>

year<sup>−</sup><sup>1</sup>

with a maximum of 3.93 Kg Ha<sup>−</sup><sup>1</sup>

*DOI: http://dx.doi.org/10.5772/intechopen.90878*

year<sup>−</sup><sup>1</sup>

obtained was 1.50 Kg Ha<sup>−</sup><sup>1</sup>

CICEG Bomberos (**Figure 7**).

of 1.62 Kg Ha<sup>−</sup><sup>1</sup>

**3.3 Ammonium**

*3.3.1 Seasonal variability*

obtained was 11.29 Kg Ha<sup>−</sup><sup>1</sup>

dry season was 1.08 Kg Ha<sup>−</sup><sup>1</sup>

year<sup>−</sup><sup>1</sup>

*Nitrate atmospheric deposition fluxes by land use.*

(IMSS-T21, at the downtown of the city) (**Figure 8**).

was 0.25 Kg Ha<sup>−</sup><sup>1</sup>

Industrial land use: Sites I, II, III, IV, V. Urban land use: Sites VI, VII, VIII, IX, X. *Mapping and Estimation of Nitrogen and Sulfur Atmospheric Deposition Fluxes… DOI: http://dx.doi.org/10.5772/intechopen.90878*

Industrial land use: Sites I, II, III, IV, V.

Urban land use: Sites VI, VII, VIII, IX, X.

In the case of sites grouped with an urban land use, it was obtained a mean value of 1.62 Kg Ha<sup>−</sup><sup>1</sup> year<sup>−</sup><sup>1</sup> with a maximum of 3.93 Kg Ha<sup>−</sup><sup>1</sup> year<sup>−</sup><sup>1</sup> . Regarding extreme values, the highest nitrate deposition fluxes were found in site X (**Figure 7**). On the other hand, in the case of sites grouped with an industrial land use, the mean value obtained was 1.50 Kg Ha<sup>−</sup><sup>1</sup> year<sup>−</sup><sup>1</sup> , with a maximum of 3.26 Kg Ha<sup>−</sup><sup>1</sup> year<sup>−</sup><sup>1</sup> . The highest flux was registered in site I, corresponding to monitoring station located at CICEG Bomberos (**Figure 7**).

According to **Figure 7**, it can be observed that nitrate deposition was slightly higher in sites with an urban land use; this agrees with the origin of nitrate, whose main source is mobile sources, which are uniformly distributed along metropolitan area of León. This hypothesis was confirmed by applying Friedman tests which demonstrated that there were not significant differences between sampling sites or land use.
