Multiparameter Probe Research Articles

VARIATION OF WATER QUALITY ALONG A RIVER IN AGRICULTURAL WATERSHED WITH SUPPORT OF GEOGRAPHIC INFORMATION SYSTEMS AND MULTIVARIATE ANALYSIS

In this work we present the application of multivariate statistical analysis and Geographic Information Systems for the conduct of studies the variation of water quality in catchment predominantly agricultural. We conducted the study in the watershed of the Rio das Lontras river/Parana; being carried out with the aid of a multi-parameter probe, in ten spots defined upstream and downstream of the watershed, in four distinct seasons. For mapping land use and occupation, we used mosaicked images dating from the year 2014, from Google Earth. The definition of the areas of influence by the Thiessen polygons technique and multivariate statistical techniques, particularly the Redundancy Analysis (RDA), were used for the correlation research between the explanatory and explanatory variables. In the area of spring, located upstream of the watershed, the contribution to the variation in water quality became smaller, compared to the other monitoring spots. In spots located downstream, we found that the interference in water quality has become greater, due to the effects of diffuse pollution along the watercourse.

Reproductive dynamics of Lycengraulis grossidens (Clupeiformes: Engraulidae) and Platanichthys platana (Clupeiformes: Clupeidae) in a subtropical coastal lagoon.

We evaluated the reproductive dynamics of two fish species, Lycengraulis grossidens and Platanichthys platana, in a subtropical freshwater coastal lagoon (Peri Lagoon) in Brazil. Samples were collected from nine sites every two months from June 2008 to April 2012. Different fishing methods were used to capture larvae, juveniles, and adults. Limnological variables were obtained using multiparameter probe. More females than males were collected of both fish species and the chi-square test (χ2) was used to confirm that the sex ratio was female-biased. Large numbers of maturing and mature fishes were observed in almost every sampling month. The gonadosomatic index (GSI) of L. grossidens was the highest in August, October, and December for females and in October for males, and no significant difference was found across years. The GSI of P. platana showed no significant difference across months for either sex; however, significant differences were recorded in year three (June 2010-April 2011) and year four (June 2011-April 2012) for females and in year three (June 2010-April 2011) for males. For both species, GSI was negatively correlated with temperature and water level. L. grossidens larvae were more abundant in October 2010, showing a positive correlation with water transparency, whereas P. platana larvae were more abundant in June 2011, showing a positive correlation with water transparency and negative correlation with temperature and precipitation. Both species were represented by different stages, including larvae, which confirm that these species reproduce in Peri Lagoon. Reproduction was more pronounced in autumn and winter; however, reproductive activity was evident throughout the sampling period. In conclusion, our results show that abiotic factors strongly influence the temporal pattern of reproductive activity and larval assemblages of both L. grossidens and P. platana in Peri Lagoon, Brazil.

Effects of water physico-chemical parameters on tilapia (Oreochromis niloticus) growth in earthen ponds in Teso North Sub-County, Busia County

Small-scale fish farmers in developing countries are faced with challenges owing to their limited information on aquaculture management. Nile tilapia farmers in Teso North Sub-County recorded lower yields than expected in 2009 despite having been provided with required inputs. Water quality was suspected to be the key factor responsible for the low yields. This study sought to assess the effects of earthen pond water physico-chemical parameters on the growth of Nile tilapia in six earthen fish ponds under semi-intensive culture system in Teso North Sub-County. The study was longitudinal in nature with pond water and fish being the units of analysis. Systematic sampling was used to select five ponds while a control pond was purposively selected based on its previously high harvest. Four ponds were fed by surface flow and two by underground water. Each pond was fertilized and stocked with 900 fry of averagely 1.4 g and 4.4 cm. Physico-chemical parameters were measured in-situ using a multi-parameter probe. Sixty fish samples were randomly obtained from each pond fortnightly for four months using a 10 mm mesh size and measured, weighed and returned into the pond. Mean range of physico-chemical parameters were: dissolved oxygen (DO) 4.86–10.53 mg/l, temperature 24-26 °C, pH 6.1–8.3, conductivity 35–87 μS/cm and ammonia 0.01–0.3 mg/l. Temperature (p = 0.012) and conductivity (p = 0.0001) levels varied significantly between ponds. Overall Specific Growth Rate ranged between 1.8% (0.1692 g/day) and 3.8% (1.9 g/day). Ammonia, DO and pH in the ponds were within the optimal levels for growth of tilapia, while temperature and conductivity were below optimal levels. As temperature and DO increased, growth rate of tilapia increased. However, increase in conductivity, pH and ammonia decreased fish growth rate. Temperature and DO ranging between 27 and 30 °C and 5–23 mg/l, respectively, and SGR of 3.8%/day and above are recommended for higher productivity.

A Multi-Parametric Device with Innovative Solid Electrodes for Long-Term Monitoring of pH, Redox-Potential and Conductivity in a Nuclear Waste Repository.

We present an innovative electrochemical probe for the monitoring of pH, redox potential and conductivity in near-field rocks of deep geological radioactive waste repositories. The probe is composed of a monocrystalline antimony electrode for pH sensing, four AgCl/Ag-based reference or Cl− selective electrodes, one Ag2S/Ag-based reference or S2− selective electrode, as well as four platinum electrodes, a gold electrode and a glassy-carbon electrode for redox potential measurements. Galvanostatic electrochemistry impedance spectroscopy using AgCl/Ag-based and platinum electrodes measure conductivity. The use of such a multi-parameter probe provides redundant information, based as it is on the simultaneous behaviour under identical conditions of different electrodes of the same material, as well as on that of electrodes made of different materials. This identifies the changes in physical and chemical parameters in a solution, as well as the redox reactions controlling the measured potential, both in the solution and/or at the electrode/solution interface. Understanding the electrochemical behaviour of selected materials thus is a key point of our research, as provides the basis for constructing the abacuses needed for developing robust and reliable field sensors.

The consequences of small-scale variations in habitat conditions driven by a floating marina on reef fish assemblages of SE Brazil

Marine constructions modify physical conditions by interfering with water circulation and increasing sedimentation and pollution, leading to biological homogenization. However, they also increase the availability of hard substrata for larval recruitment, resulting in the development of a diverse sessile community and associated fish fauna. To describe how the modifications caused by a floating marina affect reef fish assemblages at São Sebastião Channel, SW Atlantic, a multiparameter probe and a visual census methodology were used to compare the abiotic conditions and the diversity and abundance of fishes between two areas: the area inside the marina where boats are moored and the breakwater, an area more similar to nearby natural rocky shores. The area inside the marina presented more turbid and productive waters, while the breakwater was more turbulent. The abundance of fishes inside the marina was greater than at the breakwater throughout the study, but species richness was higher inside the marina only during the hot and wet period (Austral Summer and Spring). Fish assemblages were strictly different between areas. Species dominance for each area and at nearby natural rocky reefs was also different. This study shows that artificial habitat causes micro-spatial modifications to local fish assemblages. As spatial variations were related to the behavioural and ecological aspects of fishes, marine facilities should be carefully planned, and engineering principles should be combined with ecological processes to better resemble natural habitats, thereby reducing environmental impacts.

Ecology of the spider crab Libinia ferreirae (Brachyura: Majoidea): ontogenetic shifts in habitat use

We described the ecology of the spider crab Libinia ferreirae testing the habitat segregation during the ontogenetic shifts. Collections were performed monthly by trawling along the coastal area of Cananeia, Sao Paulo State (southeastern Brazil). Medusae were examined for the presence of any symbionts, and crabs were classified as juveniles (abdomen sealed to the sternite), adults (unsealed abdomen), and ovigerous females (embryos adhered to the pleopods). The environmental factors related to the water column were obtained using a multiparameter probe. In total, 564 adults and 357 juveniles were collected. However, all juveniles were obtained in association with Lychnorhiza lucerna medusae. An increase in the abundance of ovigerous females was observed as chlorophyll levels (phytoplanktonic production) increased, which is consistent with the patterns proposed for crustaceans with planktotrophic larval stages, i.e., the association of larval hatching with oceanic productivity could explain the success in juvenile recruitment approximately two months after the peak in the abundance of ovigerous females (cross-correlation: r = 0.96). This spider crab shows an ecological strategy of habitat segregation among juvenile and adult individuals, thus avoiding competition for resources among different life cycle stages.

Multiparametric Kelvin Probe Force Microscopy for the Simultaneous Mapping of Surface Potential and Nanomechanical Properties.

We report high-resolution multiparametric kelvin probe force microscopy (MP-KPFM) measurements for the simultaneous quantitative mapping of the contact potential difference (CPD) and nanomechanical properties of the sample in single-pass mode. This method combines functionalities of the force-distance-based atomic force microscopy and amplitude-modulation (AM) KPFM to perform measurements in single-pass mode. During the tip-sample approach-and-retract cycle, nanomechanical measurements are performed for the retract part of nanoindentation, and the CPD is measured by the lifted probe with a constant tip-sample distance. We compare the performance of the proposed method with the conventional KPFMs by mapping the CPD of multilayer graphene deposited on n-doped silicon, and the results demonstrate that MP-KPFM has comparable performance to AM-KPFM. In addition, the experimental results of a custom-fabricated polymer grating with heterogeneous surfaces validate the multiparametric imaging capability of the MP-KPFM. This method can have potential applications in finding the inherent link between nanomechanical properties and the surface potential of the materials, such as the quantification of the electromechanical response of the deformed piezoelectric materials.

How Does Environmental Variation Affect the Distribution of Dragonfly Larvae (Odonata) in the Amazon-Cerrado Transition Zone in Central Brazil?

This study investigated the effects of environmental variation on assemblages of dragonfly larvae (Odonata). We hypothesize that there is a significant correlation between species richness, species composition, and abundance of Odonata individuals, and habitat integrity and abiotic variables. To test this hypothesis, we sampled odonate larvae at 12 streams in the Suiá-Miçú River basin in Mato Grosso, Brazil, during three different periods of the year. Local physical and chemical variables (temperature, pH, turbidity, electrical conductivity (EC), dissolved oxygen (DO), total dissolved solids (TDS), and oxidation reduction potential (ORP)) were measured at each site using a multi-parameter probe, and integrity was assessed using the Habitat Integrity Index (HII). The variation in richness, abundance, and composition of Odonata species was related to the environmental variables analyzed, primarily by the abiotic factors pH, electrical conductivity, dissolved oxygen, total dissolved solids, and oxidation reduction potential. Our hypothesis was corroborated for the suborder Anisoptera, which showed a significant relationship with these variables, whereas Zygoptera was only related to pH. Our results show the importance of physical and chemical conditions in ecological studies using Odonata larvae as tools for the management and conservation of freshwater ecosystems.

Mechanical undulating towed vehicle for collection of oceanographic data

The need to associate the collection of oceanographic data with the use of opportunity vessels, particularly the fishing fleet, has attracted growing interest in the development of underwater equipment or vehicles fitted with multi-parameter seawater probes. Thus, four digital models of undulating tow vehicles were developed, called U-Tow, using the software program SolidWorks, to be made from fiberglass and fitted with an electronic probe that continuously gathers oceanographic data on the ship’s course, and details of the water column. The undulating system was conceived to be fully mechanical and adjustable, according to the requirements for collections performed under a wide variety of conditions stipulated by different opportunity vessels, without the need for specific training of the crew, or unnecessary occupation of space on the deck. The aim is to improve the different models presented (U-tow I to U-tow IV) in terms of their hydrodynamic, accessories for equipment protection, and ease of operation in terms of installing the probe inside the equipment.

Groundwater Heat Pump System: behavior and relationships between the groundwater temperature and electrical conductivity

The use of groundwater abstracted via open loop systems is increasingly being considered as a means to provide heating and cooling for buildings in urban contest. Physical processes affecting heat transport within an aquifer include advection (or convection) and hydrodynamic thermodispersion (diffusion and mechanical dispersion). The advective components tend to dominate the heat transfer process within the aquifer and the diffusion can be considered negligible. This study illustrates the experimental results derived from the groundwater monitoring in the surrounding area of an injection well connected to an open-loop GWHP plant which has been installed in the Politecnico di Torino (NW Italy) for cooling some of the university buildings. Groundwater pumping and injection interfere only with the upper unconfined aquifer. The data deriving from multiparameter probes installed inside the pumping well (P2), the injection well (P4) and a downgradient piezometer (S2), refers to the summer 2015. Monitoring of hydraulic levels, electrical conductivity EC and temperature T in P2, P4 and S2. The experimental results demonstrated the propagation of the subsurface thermal plume during the injection of warm water and the progressive disappearance of the temperature anomaly with time. Another important aspect that we will investigate is the unusual trend of EC values during the year and the possibility cross-correlation between EC values and T values. In particular we intend to continue this analysis to verify the reason of this data anomaly.

Water quality change of rivers during rainy events in a watershed with different land uses in Southern Brazil

ABSTRACT High frequency monitoring in environmental studies is increasingly being used due to the availability of equipment and quick response. With high frequency time series, it is possible to extract short-term responses during and after a rain event, which is not captured by conventional monitoring. The aim of this study is to evaluate the superficial water quality change of a stream in a preserved area in Atlantic Forest by short-term data (hour interval). The Cubatão do Sul watershed is located in the Central Coast region of the state of Santa Catarina in Brazil. Rain height and water quality parameters were monitored using rain gauge and multiparameter probes. Two fluviometric sections were also monitored — one in Vargem do Braço stream (FS1), which is mainly native forest (dense ombrophilous forest), and the other in Cubatão do Sul River (FS2), which is influenced by urban, agricultural and sand extraction uses. The temperature and nitrate ion permanency curve in FS1 showed slightly lower values during rainy events, but an opposite behavior was observed for turbidity. On the other hand, the permanency curves during rainy periods of FS2 presented lower conductivity and ammonium ion. When the dry and rainy periods were statistically compared, there was a significant difference for temperature, conductivity, pH, nitrate ion, turbidity and dissolved oxygen for FS1, and temperature, conductivity and turbidity for FS2. The water quality of the Cubatão do Sul watershed is influenced by stream flow and has a short-term time response considering the rain events. The oscillation of the monitored parameters between two periods, dry and rainy, is smaller in native forest than urban and rural land use.

Fish assemblages in a coastal bay adjacent to a network of marine protected areas in southern Brazil

Abstract Baía Norte (North Bay) in Santa Catarina State is considered a typical coastal bay and is surrounded by a network of Marine Protected Areas. The objectives of this study were to describe the composition of the demersal fish assemblage, identify seasonal and spatial structures on a fine scale and evaluate the role of habitat descriptors and abiotic variables affecting the fish assemblage structure. Seasonal samplings were conducted in 2005, using bottom trawls in six pre-established areas in Baía Norte in summer, fall, winter and spring. Simultaneously with each trawl, environmental data were collected with a multiparameter probe. Temporal and spatial differences in fish abundance were tested by a PERMANOVA. To illustratethe differences detected graphically we ran a canonical analysis of principal coordinates (CAP). The influence of environmental variables on the fish fauna was evaluated using a Distant Based Linear Model (DistLM) with Akaike's information criterion (AIC). A total of 9,888 specimens, distributed in 27 families and 62 species, were collected. Citharichthys spilopterus was the most abundant species. PERMANOVA detected differences for abundance between seasons, areas and interaction among all the factors. The DISTLM selected temperature and pH. The results highlight seasonality as an important factor in the structuring of fish fauna of the study place.

The Proyecto Costa Escondida: Recent interdisciplinary research in search of freshwater along the North Coast of Quintana Roo, Mexico

Access to potable water has always been a major concern for human settlement, and this is particularly acute in coastal areas where freshwater can be compromised by saline marine waters. The northeast portion of Mexico's Yucatan Peninsula has a massive freshwater aquifer that today supports the international tourist destinations of Cancun and the Riviera Maya. However, access to this aquifer in pre‐Columbian times was restricted to natural features, such as cenotes (limestone sinkholes), aguadas (freshwater ponds), and coastal springs, or cultural features like wells, the viability of which is directly linked to sea level, which has risen over 2 m in the past 3000 years. In addition, ancient Maya inhabitants of the Yucatan collected rainwater in reservoirs, smaller‐scale cisterns called chultunes, or in ceramic pots. At the coastal site of Vista Alegre, located on the north coast of the Peninsula, there is limited evidence of potable water collection strategies, which has led members of the Proyecto Costa Escondida to critically examine how the freshwater access at the site changed over the past three millennia. To do this, the interdisciplinary research team has conducted (1) a physico‐chemical characterization of accessible surface and groundwater using a calibrated multiparameter probe, (2) a multiproxy study (i.e., micropaleontology, oxygen isotopic analysis) from 12 manual push cores taken in the waters surrounding Vista Alegre, and (3) an archaeological investigation. We hope our project serves as a model for future projects that strive to understand the complex and dynamic relationships between past peoples and their coastlines. WIREs Water 2016, 3:749–761. doi: 10.1002/wat2.1161This article is categorized under: Engineering Water > Planning Water Science of Water > Water and Environmental Change Human Water > Water Governance

Benthic vegetation, chlorophyllα and physical-chemical variables in a protected zone of a Mediterranean coastal lagoon (Lesina, Italy)

Phytoplankton and benthic vegetation biomass undergoes spatial-temporal changes in relation to their life cycle, but also to meteorological conditions, physical-chemical variables, organic input and internal dynamism. The main aim of this work was to observe the effect of all environmental variables on the vegetative dynamic process in a protected zone of a Mediterranean costal lagoon (Lesina lagoon, SE Italy). Seven samplings were performed from 2010 to 2012 at 30 sites for nutrient and chlorophyll analyses, while TOC measurements and wet biomass evaluation were performed at 10 sites. Temperature, salinity and oxygen saturation were also measured by multiparametric probe and a visual census for vegetation was performed. Sites close to freshwater inflow were characterized by lower temperature and salinity, and high nitrate, with maxima of 191.05 μM in May 2010 and more than 250 μM in October 2010. Silicates drastically decreased from May 2010 (87.57 μM) to July 2010 (6.15 μM) and increased again in October (74.99 μM). Chl a concentrations were not on average higher than 6 mg m−3, but peaks of 20 mg m−3 were observed during May 2011 and May 2012. Benthic vegetation wet biomass collected in 2010 was approximately twice that collected in 2012, with a maximum of 27,554 g m−2 and a dominance of macroalgae (70 % in May 2010 and 40 % in August 2010). During period 2010, a simultaneous and drastic decreasing of both mean values of wet biomass and chl a was observed from May to October 2010. During period 2012 a shift of vegetation biomass was shown from May (phytoplankton prevalence) to August 2012, with angiosperm prevalence (more than 30 %).

Estimativa de parâmetros hidrodinâmicos do Aquífero Emborê em Farol de São Tomé - RJ Com as oscilações do nível piezométrico e maré oceânica

A obtenção e interpretação dos parâmetros físicos e químicos dos aquíferos é uma necessidade e um passo importante para o seu entendimento, pois o conhecimento sobre tais parâmetros é ainda, na maioria dos casos, incipiente. O aquífero Emborê, localizado na região Norte Fluminense, é um importante reservatório hídrico no estado do Rio de Janeiro e a população local utiliza-o para seu abastecimento. Deste modo, o conhecimento deste aquífero é de grande importância no contexto regional. O presente trabalho teve como base a instalação de um sensor multiparamétrico no poço UFRJ 05, que operou ao longo de oito meses, obtendo-se dados de temperatura, condutividade elétrica e variação da coluna de água (carga hidráulica). O poço capta o aquífero Emborê, de caráter confinado. Desta forma, o resultado das medidas de temperatura e condutividade do sensor multiparamétrico não sofreram oscilações significativas de salinidade e temperatura ao longo do período. Quanto à variação na carga hidráulica no poço, verificou-se que esta estava diretamente ligada à variação das marés oceânicas, oscilando conforme os ciclos de maré. Assim, aplicou-se metodologia de estimativa de cálculo que permitiu obter a difusividade hidráulica do aquífero em relação à maré e a comparação deste dado com os de um teste de bombeamento feito no próprio poço, avaliando-se as vantagens e desvantagens de obtenção de parâmetros do aquífero por cada método.

Spatial and temporal mangrove litter production in Barra de Navidad lagoon, Jalisco, México

Barra de Navidad lagoon is a coastal wetland of international importance (Ramsar site) and it is included among the 81 Mexican mangrove priority sites. One of the most valued characteristics of this lagoon is the presence of mangrove forest in a good conservation state. The goal of our research was the measurement of mangrove litter production and environmental factors influencing its dynamics. The mangrove area was divided into seven zones and litterfall was monthly sampled from November 2011 to October 2012 using 0.25 m(2) square collectors made with mosquito mesh (1 mm) and positioned at 1.3 m above the ground. Abiotic variables of the interstitial water were measured simultaneously at each zone in permanent plots using a multi-parameter probe, YSI-556-M. Total mean value of litterfall production, weighted by zone surface, was 19.12 ± 1.23 gPS/m(2).mo (2.29 t/ha.year). This low productivity is a consequence of the region’s dry climate and low tide range. The species Avicennia germinans and Laguncularia racemosa produced more than 80 % of total litterfall, while Rhizophora mangle contributed only 16 % and Conocarpus erectus < 4 %. A significant correlation between litterfall production and abiotic variables was found (e.g. salinity and interstitial water depth). We concluded that there are significant spatial variations in soil abiotic variables which are correlated with differences in mangrove species composition, and produce, together with the life cycles stages of those species, significant variations in the quantity and composition of litterfall. Future research will be focused on quantifying spatial variations in forest structure and their relationship with litterfall production.

Water Quality and Chlorophyll Measurement Through Vegetation Indices Generated from Orbital and Suborbital Images

The study was developed at the Municipality of Sao Gabriel do Oeste, State of Mato Grosso do Sul, Brazil, where were performed analyses of water samples, including physical and chemical aspects, obtained through Hanna multi-parameter probe into four different parts of the study area. Landsat satellite 8 (L8) and unmanned aerial vehicle (UAV) was also used to generate vegetation indices, using the visible spectral range for both types of images and normalized difference vegetation index (NDVI) just for L8. Later, these ratios were correlated to chlorophyll a that has a key role in photosynthesis. Regarding the physical and chemical parameters, the collection point 2 was the most differed to the others; this may have happened to be a dam with little flow in an eutrophication process. Through the water absorbance curve in the visible wavelengths, it is possible to estimate comparatively water body that has larger amounts of dissolved materials in the water. There was a high correlation between vegetation indices generated from aerial photographs and L8 image, with chlorophyll a extracted from water in the laboratory. In this sense, they are likely to use to forecast future scenarios. It is suggested the use of aerial photographs of UAVs for monitoring the environmental quality of small water bodies, considering its high spatial and temporal resolution.

Salinity variation in the macrotidal mixing zone: the Paracauari River estuary, Marajó Island (Northern Brazil)

ABSTRACT Monteiro, S.M. and Robrini, M., 2016. Salinity variation in the macrotidal mixing zone: the Paracauari River estuary, Marajo Island (Northern Brazil). In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 93–97. Coconut Creek (Florida), ISSN 0749-0208. The objective of this study is to delineate the estuarine zones (Riverine Zone – RZ, under river influence; Mixing Zone – MZ, under marine influence) across different seasonal periods in the macrotidal Paracauari River estuary – Marajo Island (Northern Brazil). We measured salinity (S) and electric conductivity (EC) in the water column using a multi-parameter probe. We also collected data on suspended particulate matter (SPM – gravimetric estimation) along 40 km of the estuary during higher rainfall (660 mm), transitional (260 mm), and lower rainfall (10 mm) periods in 2008. The first sampling st...

Multi-dimensional water quality assessment of an urban drinking water source elucidated by high resolution underwater towed vehicle mapping

Spatial surveys of Ramsey Lake, Sudbury, Ontario water quality were conducted using an innovative underwater towed vehicle (UTV) equipped with a multi-parameter probe providing real-time water quality data. The UTV revealed underwater vent sites through high resolution monitoring of different spatial chemical characteristics using common sensors (turbidity, chloride, dissolved oxygen, and oxidation/reduction sensors) that would not be feasible with traditional water sampling methods. Multi-parameter probe vent site identification is supported by elevated alkalinity and silica concentrations at these sites. The identified groundwater vent sites appear to be controlled by bedrock fractures that transport water from different sources with different contaminants of concern. Elevated contaminants, such as, arsenic and nickel and/or nutrient concentrations are evident at the vent sites, illustrating the potential of these sources to degrade water quality.

A Statistical Determination of the Transit Speed of Pollutants in a Water Reservoir Affected by Acid Mine Drainage from the Iberian Pyrite Belt

The El Sancho reservoir is located in the Odiel River basin, which crosses the Iberian Pyrite Belt. The reservoir receives acid mine drainage (AMD) from the Meca River, a tributary of the Odiel River. Two multi-parameter probes, one placed at the tail (up-gradient) end of the reservoir, where the contaminants enter, and another close to the reservoir dam were used to characterize acidity migration through the Sancho reservoir. The probes both measured pH and conductivity every 30 min. Two different levels of contamination were found, due to dilution that takes place within the reservoir and changes in the AMD composition. The cross-correlation function allowed quantification of the migration process from tail to dam. For both pH and conductivity, the maximum correlation occurred 17 days after sampling, indicating a mean transit time of 17 days. Since the distance between the two sampling points was 14,500 m, the contaminant transit speed was 0.0098 m/s.