B. Carro

Impact of millennial mining activities on sediments and microfauna of the Tinto River estuary (SW Spain).

In this paper, we analyze two short cores collected in the Tinto estuary (SW Spain), and describe the palaeoenvironmental evolution of this area during the last two millennia, along with the influence of historical mining activities and recent industrial pollution on sediments and microfauna (foraminifera and ostracoda). Although there were no significant changes in the distribution of microorganisms, a first pollution period (0-150 AD) was recorded in high sediment pollution by Cu in the shallow palaeochannels of the middle estuary. During this period and the following 1700 years, tolerant pioneer species of both foraminifera and ostracoda were found predominantly in the inner, protected areas of the estuary, while the bottom sediments were subjected to high hydrodynamic gradients, and consequently showed lower density and diversity of organisms. In the last 150 years, acid mine drainage processes, introduction of a new mining period, and the polluted inputs derived from two industrial processes resulted in increased heavy metal contamination of the bottom sediments, and corresponding extirpation of ostracodes and restriction of foraminifers to the inner zones of the estuary.

Effect of acid mine drainage on dissolved rare earth elements geochemistry along a fluvial-estuarine system: the Tinto-Odiel Estuary (S.W. Spain)

Hydropower is a potential large source of electricity supply in Wales. The Upper River Severn in Mid Wales is a typical stream where a high head hydropower scheme could be developed and the river system at Plynlimon has some of the longest records for weather and flow in Wales. A microhydropower potential of 99 kW is demonstrated at Plynlimon and the potential impacts of climate change are simulated to assess the effects on flows and power outputs of such schemes under climate uncertainty. Based on UK Climate Projections 2009 (UKCP09) projections, the impacts of climate change are to significantly decrease both the stream flows and energy production during summer months but to increase flows and power production in the winter, with a net tendency to cancel out over the course of a full year. A methodology for assessing impacts of climate change on hydropower is established, which could be applied more widely to other potential hydropower sites such as lowland rivers or high base flow rivers in other parts of the UK. This will be useful for developers, water companies and environmental agencies to assess hydropower potential, economic viability and environmental impacts of micro-hydropower, under future climate change. doi: 10.2166/nh.2012.012 s://iwaponline.com/hr/article-pdf/44/3/495/370465/495.pdf D. Carless (corresponding author) Southern Hydropower, King William House, London Road, Blewbury, Oxfordshire OX11 9PD, UK E-mail: dave@southernhydropower.co.uk P. G. Whitehead School of Geography and the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, UK

Hydrogeochemical variables regionalization – applying cluster analysis for a seasonal evolution model from an estuarine system affected by AMD

This study describes the spatial evolution of the hydrogeochemical parameters which characterise a strongly affected estuary by Acid Mine Drainage (AMD). The studied estuarine system receives AMD from the Iberian Pyrite Belt (SW Spain) and, simultaneously, is affected by the presence of an industrial chemical complex. Water sampling was performed in the year of 2008, comprising four sampling campaigns, in order to represent seasonality. The results show how the estuary can be divided into three areas of different behaviour in response to hydrogeochemical variables concentrations that define each sampling stations: on one hand, an area dominated by tidal influence; in the opposite end there is a second area including the points located in the two rivers headwaters that are not influenced by seawater; finally there is the area that can be defined as mixing zone. These areas are moved along the hydrological year due to seasonal chemical variations.

Estuaries of the Huelva Coast: Odiel and Tinto Estuaries (SW Spain)

The estuary of the Odiel and Tinto rivers is located in the southwest of the Iberian Peninsula on the western Gulf of Cadiz (Atlantic Ocean). The Huelva estuary is constituted by the common mouth of the Odiel and Tinto Rivers in a “Y” shape oriented in a N-S direction across 35 km long incised valley. This estuary was generated after the Flandrian Transgression (Holocene), which signified the marine inundation of the main fluvial valleys incised by the rivers during the last Pleistocene lowstand. It extends along the south-western coastal margin of the Guadalquivir sedimentary basin that was incised on Cenozoic non-consolidated sediments during the late Pleistocene and early Holocene when sea level was located up to 100 m below the present position. This estuary is presently completely filled with sediments and has started to prograde to build a delta. The fluvial basin of both rivers is seriously affected by acid mine drainage, so this estuary have a induces important changes in the chemical characteristics of the water, suspended particulate matter (SPM) and sediments.