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The monitoring effort of Lissos River, located in Rhodope County, Thrace, North Greece, is presented. The river springs from Rhodope mountains and discharges into the Thracean Sea in the North Aegean, in an area protected by the Ramsar Convention. There are point and non-point pollutant sources in Lissos watershed resulting from human activities. Monitoring of Lissos River is essential for two reasons: first its water is used for irrigation of cultivated fields, and second it is included into the EU "Natura 2000" network. For the purposes of this study, a data collection program was established, aiming to collect data useful for the evaluation of the water quality of the river and its trophic state. The data include the following: (a) hydrologic (i.e., precipitation, air temperature, etc.) in a total of 2 stations over the watershed; (b) streamflow and sediment transport (i.e., cross-sectioning, velocity, suspended sediment, etc.) in a total of 7 stations in various torrents and in the main river course, at a frequency of ten days; (c) Electrical Conductivity (EC), pH, Dissolved Oxygen (DO) and Temperature (T) measured in situ simultaneously with discharge measurements; and (d) water samples collected and analyzed for the determination of Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), nitrates, nitrites, ammonium, total phosphorus (TP), ortho-phosphates (OP), alkalinity and various anions (i.e., SO42, CF) and cations (i.e., Na+, K+, Mg+2, Ca+2). Monitoring results showed influence on the EC values and nitrogen and phosphorus concentrations in the tributary of Lissos where a wastewater treatment plant discharges its effluent. The one-way between groups ANOVA showed that there were statistically significant differences of mean values of measured parameters (i.e., BOD, COD, TP, CF, SO4-2 etc.) between various stations of the river, indicating pollutant sources. The trophic state of Lissos was found eutrophic due to increased concentrations of nutrients, indicating the need for management measures in order to improve river water quality. The water quality of Lissos River, for irrigation use, was found satisfactory and suitable for almost all crops. [ABSTRACT FROM AUTHOR]

The role and importance of evapotranspiration (ET) on constructed wetland (CW) operation is examined through controlled experiments. For this, ten pilot-scale, cylindrical, thermally insulated metal tanks, of diameter 1.5 m and height 1.0 m, operated as lysimeters to evaluate CW ET. Four different substrate materials were used, i.e., river sand, medium gravel, cobbles and clay soil, with a total thickness of 0.5 m. The plant types used were Phragmites australis (reeds) in two CW units, Arundo Donax (giant reeds) in two units and Typha latifolia (cattails) in four units, while two units were unplanted. Six units simulated horizontal subsurface flow (HSF) CWs and four units free-water surface (FWS) systems. Under this configuration, interesting conclusions were drawn about the effect of substrate material, plant and CW type on ET rates. All units operated for nine months (April to December 2009), during which daily measurements of ET were made based on the water budget method. Results show a seasonal variation of ET values (higher values in summer, lower in winter) for all planted units, while the unplanted units had significantly lower variations. Overall, higher ET values were observed for the units planted with reeds, while cattails were more active during the summer months. Pearson correlation coefficients were computed to identify meteorological and other parameters affecting CW ET. The measured data were also used to produce simple empirical relations to predict daily ET rates based on meteorological and other parameters. [ABSTRACT FROM AUTHOR]

The contribution of bottom sediments to the trophic status of two adjacent lagoons located in Northern Greece is investigated. The limited water depths (about 1 m) and the depletion of oxygen occurring in the summer suggest that there may be a nutrient release from the bottom sediments to the water column. Temperature, salinity, pH and dissolved oxygen concentration in the water column were measured onsite using suitable portable equipment. Nitrites, nitrates, total phosphorus and chlorophyll-a were determined in water samples, whereas total Kjeldahl nitrogen and total phosphorus in sediment samples. Nutrient concentrations in the water column of Eratino Lagoon increased during the winter (nitrate: from 69 to 76 µg l-1; total phosphorus: from 93 to 116 µg l-1). Nutrient concentrations also increased in Vassova Lagoon. Chlorophyll-a concentration appeared to be nearly stable in both lagoons. Total Kjeldahl nitrogen in the sediment showed increased winter values, especially near the agricultural drainage canal of Eratino Lagoon (10.7 mg l-1). On the contrary, total phosphorus in the bottom sediments decreased by almost one order of magnitude in Eratino Lagoon (from 468 to 26 µg g-1 d.w.), and less in Vassova Lagoon, revealing a phosphorus release from bottom sediments into the water column. Both lagoons were characterized as mesotrophic to hypertrophic. Best management practices have to be implemented in order to improve the water and sediment quality of these two lagoons. [ABSTRACT FROM AUTHOR]