Volume 45, Nº 6 (2018)

Methods for the analysis of the formation of river water chemistry based on mixing models are discussed. An analytical solution for a mixing model of four recharge sources is given along with the results of its adaptation based on the materials of hydrochemical and hydrological observations over 2013 and 2014 in drainage basins in Primorski Krai. The analysis and calculations revealed four components of river recharge in these years: rainwater, two types of subsoil water, and groundwater, the latter forming the base runoff. The estimates of the mixing model with four sources and its tests showed a high quality of modeling.

The hydroclimatic conditions of water runoff formation and the hydrography of Parana and Uruguay river basins in the South America are considered. A survey of the recent studies of the hydrological regime of these rivers is given. Observation data are used to evaluate the long-term average values of water runoff and suspended sediment yield in the Parana and Uruguay and their variations along the rivers. Characteristics of many-year runoff variations in the rivers were evaluated. A climate-induced increase was identified in the Parana and Uruguay water runoff, and the corresponding present-day trends in river runoff variations in both rivers were evaluated. The total water runoff and suspended sediment yield of the Parana and Uruguay into La Plata estuary were calculated. Water balance of the drainage basin of La Plata estuary was characterized.

The natural and anthropogenic sources of iron, copper, and zinc in water streams in the Republic of Bashkortostan are considered. Statistical analysis of long-term hydrochemical monitoring data was used to establish the spatial year-to-year and annual regularities in metal concentrations in water streams. The acceptability of river water quality for different types of water use was estimated. The exceedance probabilities of metal MAC values in streams were evaluated.

Long-term dynamics of water level in Lake Nero (1930–2011) has been analyzed. Pronounced trends, determined by the climate and anthropogenic components have been identified. Up to the 1970s, at a drop in lake water level, the ecosystem still showed the main features of a shallow water body overgrown with macrophytes. Water level rise caused a more intense development of phytoplankton, an increase in biogenic element concentrations, a decrease in water transparency and the contribution of cyanobacteria of S₁ codon; pondweed disappeared almost completely. Step-by-step regression analysis of phytoplankton development indices and hydrological characteristics showed that water transparency in Lake Nero depends by 80% directly on water exchange and inversely on the concentration of chlorophyll a in seston. The main hypothesis of the study was confirmed: the key trigger in phytoplankton–macrophytes competition is water level rise.

Hydrochemical data collected in field studies in the near-mouth area and delta of the Don R. (Aksay T.—the mouths of Don delta branches) in 2006–2015 are analyzed. The seasonal dynamics is demonstrated, and the average annual concentrations were evaluated for mineral, total dissolved, and total forms of nitrogen, phosphorus, silica; dissolved and particulate organic carbon; and total suspended solids in river water. The export of dissolved and particulate organic carbon and nutrients by the Don River into the Sea of Azov in the low-water period of 2007–2015 is evaluated. Retrospective analysis of nutrient export into the Sea of Azov with river runoff in the XX–early XXI century is given.

Identification of contaminants, determination of their biological hazard and content in water are important practical tasks while assessing water quality in sources of drinking water supply of large cities. Presented herein is a review regarding pharmaceutical pollution of waters in various countries. Given are original data concerning contamination of water objects—sources of water supply of Moscow with components of pharmaceuticals and metabolites of therapeutic agents. Worked out is a retrieval and calculation technology of assessing hazards of substances. Proposed is the use of “structure-activity” calculation technologies for prediction of side effects of pharmaceuticals and pharmacological activity of other organic xenobiotics not used in medicine. Certain ways of decreasing pharmaceutical pollution are recommended.

The aim of this study was to display distribution and relationships of heavy elements in the unconfined, shallow alluvial aquifers of the lower Jia Bharali catchment and adjoining areas in central part of North Brahmaputra Plain (NBP), India using hydrochemical as well as multivariate statistical techniques such as principal component analysis (PCA) and cluster analysis. The original matrix was made up of 10 trace elements (As, Cd, Cu, Co, Cr, Fe, Mn, Pb, Ni and Zn) estimated from 50 shallow alluvial dug wells in both the wet and the dry season for a duration of 3 hydrological years (2008–2011). Except As, Cu and Zn all the other toxic metals in the shallow aquifers were found exceeding the WHO maximum permissible limits for drinking water. PCA extracted five varimax factors as geogenic, agricultural and anthropogenic explaining about 71.2% of the total variance in the wet season and 69.3% total variance in the dry season. Hierarchical cluster analysis classified the dug wells into two groups in the wet season and three groups in the dry season with respect to the heavy elements. The results emphasized the need for routine monitoring and management in order to avoid contamination of groundwater sources in the NBP with respect to the dissolved trace elements.

The ponds are natural water resources used for drinking, bathing, washing and aqua culture. In this work, the contamination of ponds lied in central India with F^– and heavy metals (As, Sb, Cr, Mn, Fe, Cu, Zn, Cd, Pb, Th and U) is described. The F^– concentration in the pond water and sediment (n = 24) was ranged from 1.6–5.5 mg/L and 210–1430 mg/kg with mean value of 2.3 ± 0.4 mg/L and 599 ± 137 mg/kg, respectively. The concentration variation and sources of the elements in the pond water and sediment are discussed. The health hazards of F^– in the domestic animals are described.