Valery Rodinov

Heavy metals in rivers of Latvia

Total heavy metal concentrations in waters and sediments (HNO3 digestible Pb, Cu, Co, Ni, Mn, Zn) and their speciation forms in sediments (exchangeable, carbonate bound, iron-manganese oxide bound, organic matter bound and residual) in major and common small watercourses (31 sampling stations) along their flow in Latvia were determined. The metal loads entering the Baltic Sea from Latvia were calculated. Increased metal concentrations were found only in lower reaches of the largest rivers and locally around known industrial pollution sources. Differences in metal concentrations and loads in rivers from different regions of Latvia were related to natural geochemical processes. Metal speciation analysis showed that the dominant metal species are residual metals and those bound to organic matter. Residual and carbonate-bound metal dominated only in rhitral regions of rivers. The concentrations of exchangeable metals increased below pollution sources.

Metal accumulation in sediments and benthic invertebrates in lakes of Latvia

The concentrations of cadmium, lead, nickel and copper in waters, sediments (total metal concentrations and their speciation forms) and benthic macroinvertebrates in 11 lakes of Latvia were determined using atomic absorption spectroscopy. Metal concentrations in lake waters, sediments and biota were compared with water chemistry. Compared to total concentrations, metal speciation forms in sediments were better correlated with respective metal concentrations in invertebrates. Therefore, the evaluation of potential metal bioaccumulation should consider metal speciation. The mean concentrations of trace metals in benthic invertebrates in Latvia were much lower than in other countries, which can be explained by comparatively lower anthropogenic loads. However, local areas of anthropogenic impacts were evident.

Metals in sediments of lakes in Latvia

Abstract The concentrations and speciation forms of Pb, Cu, Ni, Cd, Zn, and Mn have been determined in sediments from 49 lakes thoroughout Latvia to study the impact of different pollutant sources and to estimate the background pollution level. Regional variation in pollutant distributions of Pb, Cu, and Cd concentrations is due to anthropogenic load. The enrichment of metals in the top layer of sediments is an estimate of the environmental pollution level. In regions with no known pollution sources, this enrichment was not typical. Another factor that determines metal concentrations in sediments is the organic matter production and sedimentation in eutrophic water bodies.

Trends of natural organic matter concentrations in river waters of Latvia

This study revealed significant (P < 0.1and P < 0.05) increasing trends of total organic carbon (TOC) and water colour in most of the studied Latvian rivers during the last decade. However, over longer time periods, there were pronounced oscillations of TOC concentrations, similar to patterns of long-term changes of river discharge regime. On a yearly basis, there was a positive correlation between parameters of organic matter concentration and discharge in all selected rivers (rS = 0.540–0.803; P < 0.01). The impact of discharge on concentrations of organic matter could be masked by other factors, such as changes in precipitation, biological processes, soil types or land use.

Long-term and seasonal changes in chemical composition of surface waters in Latvia.

The changes of the chemical composition in Latvianinland waters over the last twenty years weredetermined, based on data of the National MonitoringProgramme. Relationships between the water compositionwere studied. The chemical composition and seasonalchange pattern depend a lot on hydrological factorswhich differed between eastern and western Latvia.Different pattern of long-term changes is found forsubstances which have different sources andsinks, at first for nutrients (decrease only in the lastfew years) and inorganic ingredients (commonlyincreasing trend). An attempt was made to identify themain sources of the major water ingredients and linkchanges of their concentrations with changes inloading to waters.

Ice regime of rivers in Latvia in relation to climatic variability

lee freeze-up and break-up reeords for rivers allow assessment of long-term and seasonal elimate variability, espeeially in relation to elimate ehange (LivINGSTONE 1997, SINGH & KUMAR 1997, MAGNUSON et al. 2000). lee regime studies are important beeause: (l) ealendar dates o f freezing and thawing o f lakes and rivers were reeorded for many rivers well before seientifie observations began, therefore the data eover a longer period than hydrologieal faetors; (2) iee regimes model the hydrologieal regime during the period o f maximal diseharge o f aeeumulated atmospherie preeipitation; and (3) iee eonditions are sensitive and reliable indieators of elimate. River diseharge and iee regime is influeneed by the global warming proeess (SINGH et al. 2000). lee dates for the last two eenturies on rivers in the Northem Hemisphere provide eonsistent evidenee of later freezing and earlier break-up (MAGNUSON et al. 2000). Several studies have analyzed iee regime trends for inland waters using easily identifiable parameters deseribing iee break-up reeorded for a long period of time (BENSON et al. 2000, LIKENS 2000, ARAI 2000). The iee regime ofthe Baltie Sea was previously analyzed using a historieal time series of iee break-up at the port o f Ri ga (JEVREJEVA 200 l) to reeonstruet the elimate (TARAND & NORDLI 2001). The aim ofthe present study is to assess long-term iee regime ehanges of Latvian rivers in relation to long-term elimate ehange and river diseharge.

Well water quality in Latvia

A total of 2500 water samples from drinking water shallow wells and boreholes in rural areas of Latvia were collected. The samples were analyzed for 20 parameters. Well waters in Latvia can be characterized by a high content of organic (humic) substances. Mean values for analyzed water parameters are: 0.17 mg/1 NH4, 0.016 mg/1 NO2, 2.90 mg/1 NO3, 0.028 mg/1 PO4, 25.53 mg/1 Cl, 0.12 mg/1 Fe, 7.4 pH, 784 μ/cm conductivity, 24 degrees in PtCo scale color, 7.5 mgequiv/1 total hardness. Comparison with water quality criteria adopted in the USA and European Communiy indicate that water quality is often unsatisfactory. For example, nitrate concentrations exceed standards in nearly 20% of the surveyed wells. The main problems of drinking water quality in Latvia are associated with increased concentrations of nitrogen and organic matter, and increased mineralisation. Concentrations of most water substances are dependent on local factors, and some vary substantially between different regions of Latvia. However, con...