Water quality time series for Big Melen stream (Turkey): its decomposition analysis and comparison to upstream

Big Melen stream is one of the major water resources providing 268 km³ year^???1 of drinking and municipal water for Istanbul. Monthly time series data between 1991 and 2004 for 25 chemical, biological, and physical water properties of Big Melen stream were separated into linear trend, seasonality, and error components using additive decomposition models. Water quality index (WQI) derived from 17 water quality variables were used to compare Aksu upstream and Big Melen downstream water quality. Twenty-six additive decomposition models of water quality time series data including WQI had R ² values ranging from 88% for log(water temperature) (P?≤?0.001) to 3% for log(total dissolved solids) (P?≤?0.026). Linear trend models revealed that total hardness, calcium concentration, and log(nitrite concentration) had the highest rate of increase over time. Tukey’s multiple comparison pointed to significant decreases in 17 water quality variables including WQI of Big Melen downstream relative to those of Aksu upstream (P?≤?0.001). Monitoring changes in water quality on the basis of watersheds through WQI and decomposition analysis of time series data paves the way for an adaptive management process of water resources that can be tailored in response to effectiveness and dynamics of management practices.     

Quantifying long-term changes in water quality and quantity of Euphrates and Tigris rivers, Turkey

The Euphrates and Tigris watersheds originating from Turkey and passing through Syria and Iraq are one of the most important transboundary watersheds in the Middle East. Long-term data (1971 to 2002) from 14 stations over the Euphrates river and seven stations over the Tigris river were analyzed and compared using the nonparametric Kruskal–Wallis and Mann–Kendall trend tests, and box-and-whisker plots. The upper Euphrates river had significantly lower values of flow rate (FR), water temperature (WT), electrical conductivity (EC), Cl, and SO₄ than did the lower Euphrates river. The middle Euphrates river had significantly higher Na, K, HCO₃, Cl, sodium adsorption ratio (SAR), and boron (B) and lower EC and SO₄ than the lower Euphrates river. The upper west Tigris river had higher EC, Ca + Mg, and SO₄ and lower FR, Na, and SAR than the lower Tigris river. The upper east Tigris river had higher HCO₃ and B and lower FR and WT than the lower Tigris river.     

Nickel accumulation and its effect on biomass, protein content and antioxidative enzymes in roots and leaves of watercress （Nasturtium officinale R. Br.）

In order to understand its response towards nickel stress, watercress (Nasturtium o cinale R. Br.) was exposed to nickel (1–25 mg/L) for 1, 3, 5 and 7 days. The accumulation and translocation of nickel were determined and the influence of nickel on biomass, protein content and enzymatic antioxidants was examined for both roots and leaves. It was determined that N. o cinale could accumulate appreciable amounts of Ni in both roots and leaves. Nickel accumulated particularly in the roots of plants. Biomass increased at low nickel concentrations but certain measurable change was not found at high concentrations. Under stress conditions the antioxidant enzymes were up-regulated compared to control. An increase in protein content and enzyme activities was observed at moderate exposure conditions followed by a decline at both roots and leaves. The maximum enzyme activities were observed at di erent exposure conditions. Our results showed that N. o cinale had the capacity to overcome nickel-induced stress especially at moderate nickel exposure. Therefore, N. o cinale may be used as a phytoremediator in moderately polluted aquatic ecosystems.     

Comparative thermodynamic performance analysis of a cascade system for cooling and heating applications

In this study, a comparative thermodynamic performance analysis of cascade system (CCS) for cooling and heating applications is presented and compared for different refrigerant couples. The CCS consists of the low-temperature cycle (LTC) and high-temperature cycle (HTC). The CO₂ was used as working fluid in LTC, whereas the HFE 7000, R134a, R152a, R32, R1234yf, and R365mfc refrigerants were used in HTC. The heating and cooling coefficients of performance (COP_ht, COP_cl) and exergy efficiency of CCS are investigated parametrically according to various factors such as the evaporator, condenser, and reference temperatures. After thermodynamic analyses are completed, the COP_cl of CCS is obtained as 1.802, 1.806, 1.826, 1.769, 1.777, and 1.835 for CO₂-HFE7000, CO₂-R134a, CO₂-R152a, CO₂-R32, CO₂-R1234yf, and CO₂-365mfc refrigerant couples, respectively. Furthermore, the heat exchanger has the highest exergy destruction rate, whereas the expansion valves have the lowest of exergy destruction rate.     

Morin protects against acrylamide-induced neurotoxicity in rats: an investigation into different signal pathways

Environmental Science and Pollution Research - The presented study investigates the effects of morin against toxicity induced by acrylamide (ACR) in the brains of Sprague Dawley rats. In this...     

Monitoring and validating spatio-temporal dynamics of biogeochemical properties in Mersin Bay (Turkey) using Landsat ETM+

The objective of this study was to devise and validate simple models for estimating spatio-temporal dynamics of seven optically (in)active biogeochemical properties in Mersin Bay using Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data and GIS. Spatio-temporal dynamics of Secchi depth (S (depth)), dissolved oxygen (DO), nitrite nitrogen (NO(2)-N), nitrate nitrogen (NO?-N), silicate (SiO?), 5-day biological oxygen demand (BOD5), and chlorophyll-a (Chl-a) were estimated using best-fit multiple linear regression (MLR) models as a function of Landsat 7 ETM+ and ground data in 2007 and 2008, latitude, longitude, and day of year. Validation of the MLR models against Landsat and ground data in 2005 led to r values ranging from 0.39 for NO?-N (P?=?0.008) to 0.79 for S (depth) (P?相似文献   

Long-term spatiotemporal patterns of CH4 and N2O emissions from livestock and poultry production in Turkey

This study quantified spatiotemporal patterns of CH₄ and N₂O emissions from livestock and poultry production in Turkey between 1961 and 2007. CH_4(enteric) (from enteric fermentation), CH_4(manure) (from manure management), and N₂O_(AWM) (from animal waste management) emissions in Turkey were estimated at 1,164, 216, and 55 Gg in 1961 and decreased to 844, 187, and 39 Gg in 2007, contributing a share of roughly 2% to the global livestock-related CH₄ emissions and %1.5 to the global N₂O_(AWM) emissions, respectively. Total CO₂-eq emissions were estimated at 50.7 Tg in 1961 and declined from a maximum value of 60.7 Tg in 1982 to a minimum value of 34.5 Tg in 2003, with a mean emission rate of 48 Tg year^???1 due to a significant reduction in the number of ruminant livestock. The highest mean share of emissions belonged to West Black Sea (14% and 16%) for CH_4(enteric) and CH_4(manure) and to North East Anatolia (12% and %13) for N₂O_(AWM) and total CO₂-eq emissions, respectively. The highest emission density was 1.7 Mg km^???2 year^???1 for CH_4(enteric), 0.3 Mg km^???2 year^???1 for CH_4(manure), and 0.07 Mg km^???2 year^???1 for the total CO₂-eq emissions in the West and North East Anatolia regions and 0.09 Mg km^???2 year^???1 for N₂O_(AWM) in the East Marmara region. Temporal and spatial variations in CH_4(enteric), CH_4(manure), and N₂O_(AWM) emissions in Turkey were estimated using regression models and ordinary kriging at a 500-m resolution, respectively.     

Analyzing riparian forest cover changes along the Firniz River in the Mediterranean City of Kahramanmaras in Turkey

Riparian forests adjacent to surface water are important transitional zones which maintain and enrich biodiversity and ensure the sustainability in a forest ecosystem. Also, riparian forests maintain water quality, reduce sediment delivery, enhance habitat areas for aquatic life and wildlife, and provide ecological corridors between the upland and the downstream. However, the riparian ecosystems have been degraded mainly due to human development, forest operations, and agricultural activities. In order to evaluate the impacts of these factors on riparian forests, it is necessary to estimate trends in forest cover changes. This study aims to analyze riparian forest cover changes along the Firniz River located in Mediterranean city of Kahramanmaras in Turkey. Changes in riparian forest cover from 1989 to 2010 have been determined by implementing supervised classification method on a series of Landsat TM imagery of the study area. The results indicated that the classification process applied on 1989 and 2010 images provided overall accuracy of 80.08 and 75 %, respectively. It was found that the most common land use class within the riparian zone was productive forest, followed by degraded forest, agricultural areas, and other land use classes. The results also indicated that the areas of degraded forest and forest openings increased, while productive forest and agricultural areas decreased between the years of 1989 and 2010. The amount of agricultural areas decreased due to the reduction in the population of rural people. According to these results, it can be concluded that special forest management and operation techniques should be implemented to restore the forest ecosystem in riparian areas.     

Spatial Distribution and Temporal Change of Carbon Storage in Timber Biomass of Two Different Forest Management Units

Forests make up large ecosystems and can play an important role in mitigating the emissions of CO₂, the most important greenhouse gas. However, they are sources of atmospheric carbon when they are disturbed by human or natural causes. Storage of carbon through expansion and adaptive management of forest ecosystems can assist in reducing carbon concentrations in atmosphere. This study proposes a methodology to produce spatially explicit estimates of the carbon storages (aboveground plus belowground) depending on land use/cover changes in two different forest ecosystems during various periods. Carbon storages for each forest ecosystem were projected according to inventory data, and carbon storages were mapped in a geographic information system (GIS). Results showed that total carbon stored in above and belowground of both forest ecosystems increased from one period to other because of especially increase of productive forest areas and decline of degraded forest areas as well as protection of spruce forests subject to insect attacks.     

Seasonal Variability of Heavy Metals in Surface Sediment of Lake Sapanca, Turkey

Lake Sapanca is exposed to heavy urbanization and industrialization because of its natural beauty and its proximity to the metropolitan İstanbul, Turkey. In this study, it was aimed to investigate seasonal changes of some heavy metals (Pb, Cr, Cu, Mn, Ni, Zn and Cd) concentration of surface sediment. Nine different stations were chosen as sampling points. Samples were taken every three months and the seasonal and annual average concentration of the elements were determined. Seasonal highest values of heavy metals were observed as follows; Cr, Cu, Mn, Ni and Zn in Summer, Cd in Autumn. There was no seasonal difference for Pb, Cr and Cd. It seems that Lake Sapanca has not been polluted yet. However, it was found that Cu and Ni concentrations in surface sediment exceed lowest effect level.