TITLE:
Differences in arsenic, molybdenum, barium, and other physicochemical relationships in groundwater between sites with and without mining activities
AUTHORS:
Lia Méndez-Rodríguez, Tania Zenteno-Savín, Baudilio Acosta-Vargas, Jobst Wurl, Miguel Imaz-Lamadrid
KEYWORDS:
Arsenic; Barium; Molybdenum; Water Quality; Ore Deposits
JOURNAL NAME:
Natural Science,
Vol.5 No.2A,
February
27,
2013
ABSTRACT:
The characteristic
relationships of trace metals and other water quality parameters in a specific
region can be affected by anthropogenic activeties. Since the mid-18th century
in the southwestern part of the Baja California Peninsula, intermittent gold
mining activities have been developed. We analyzed 36 water quality parameters
in accordance with the procedures suggested by international agencies to
evaluate the impact of this activity and the time of year on the mobilization
of trace element levels and their relationships in groundwater. Quantifiable
levels of molybdenum help to establish the area influenced by ore deposits
because it is one of the three elements in the paragenesis associated to gold.
Arsenic in sites closer to ore burning areas was associated with cobalt,
indicating the potential presence of a by-product generated from arsenolite;
whereas in the non-mineralized area, it was associated with barium, forming a
compound that tends to precipitate, thereby maintaining a natural geochemical
control in this region. From the sites sampled, 45% exceeded the limit for
arsenic (10 μg/l) established by international agencies. During area monitoring
with annual precipitation of 207
mm, only seven of 36 parameters analyzed showed significant differences
in relation to time of year.