Leaching and transport of Zn through soil profiles in a seasonal river of a mining area in SE Spain

Metal pollution can have adverse effects on human health but also on environment. Usually,
risk is assessed on the basis of the total concentration of a trace metal in soils and sediments.
Nevertheless, for checking the short and long-term true environmental impact of a trace
element, one of the most crucial factors to consider is its mobility. Leachability of metals from
soils and sediments and, thus, their mobility, depends on several factors such as the soil type
on the basis of the parameters that affect metal interaction, the nature of the pollution in terms
of the deposition and composition, and finally the environmental conditions that may lead to
weathering. This study has been focused on the metal behaviour in some soil and sediment
profiles placed in the river-bed of a seasonal river from a semiarid mining Mediterranean area,
in SE Spain. Data from these analyses showed that a change of the environment conditions
could remobilise great amounts of Zn. In this sense, a change of acidic conditions could affect
mainly to the lower drill. Meanwhile a change of reducing or oxidizing conditions can affect to
middle and upper drills zinc remobilization. Middle stretch of the seasonal river shows a very
different behaviour in relation to zinc mobility, leachibility and distribution in soil profiles. For
this river stretch, metal accumulation in the soil profile is higher, and leachibility risks for
groundwater could be higher. Besides, the lower stretch of the seasonal river show a special
metal distribution because of the underlying materials are placed in the saturated zone
(marine aquifer), what can determinate a horizontal, more than a vertical, metal flux.