Vladimir Majer

Trends in Surface Water Chemistry in Acidified Areas in Europe and North America from 1990 to 2008

Acidification of lakes and rivers is still an environmental concern despite reduced emissions of acidifying compounds. We analysed trends in surface water chemistry of 173 acid-sensitive sites from 12 regions in Europe and North America. In 11 of 12 regions, non-marine sulphate (SO4*) declined significantly between 1990 and 2008 (−15 to −59xa0%). In contrast, regional and temporal trends in nitrate were smaller and less uniform. In 11 of 12 regions, chemical recovery was demonstrated in the form of positive trends in pH and/or alkalinity and/or acid neutralising capacity (ANC). The positive trends in these indicators of chemical recovery were regionally and temporally less distinct than the decline in SO4* and tended to flatten after 1999. From an ecological perspective, the chemical quality of surface waters in acid-sensitive areas in these regions has clearly improved as a consequence of emission abatement strategies, paving the way for some biological recovery.

The effect of pH and atmospheric deposition on concentrations of trace elements in acidified freshwaters: A statistical approach

A statistical evaluation of 5 338 analysis of freshwaters from little polluted stream basins in the Czech Republic indicated a relationship between the Pb, Cu, Zn, Cd, Be, As, Mn, Sr, F− and Fe concentrations and the pH, over a range of pH 3.6 to 9.6. Except for Sr, the median concentrations of all the trace metals increase with decreasing pH, but the increase never extends over the whole studied acidic range (pH 3.6 to 7.0). Acid deposition related mobilization of Mn and Be into freshwaters explains the sharp increase in their concentrations with decreasing pH. Cadmium and Zn are also mobilized n strongly acidic environment. The concentrations of Be, As, F− and Mn in strongly acidic waters and those of Zn and Cd in weakly acidic ones are considerably higher in areas receiving a higher atmospheric loading. For Be and Mn, the higher concentrations are caused by higher acid deposition rates, while for As and F−, the concentrations are probably greater due to higher atmospheric deposition of these elements over more intensely acontaminated areas of the Czech Republic.In extremely acidic waters (pH < 4.2), the concentrations of Mn, Be, Cd, Zn and Al no longer increase with decreasing pH; on the contrary, those of Mn and Be actually decrease. This seems to be primarily caused by a decrease in their concentrations within the surface horizons of soils and vegetation induced by prolonged leaching. The Cd and Zn concentrations are independent of pH over an interval of pH 5.4 to 6.0 and thus the increase in the mean concentrations of Cd and Zn with decreasing pH involves two separate stages, at pH > 6.0 and at pH < 5.4.The concentrations of Cu in acid freshwaters are controlled by both the presence of high molecular weight organics plus biota uptake and by their atmospheric deposition levels; the concentrations of As and Pb are in addition controlled by sorption on Fe - oxyhydroxides. These elements accumulate in the topsoil, even under conditions of severe acidification. The surprisingly lower concentrations of Pb and Cu were found in acidic waters of more contaminated areas.

Chemical recovery of acidified Bohemian lakes between 1984 and 2012: the role of acid deposition and bark beetle induced forest disturbance

Assessment of temporal trends and rates of change in hydrochemical parameters and forest cover has been conducted to elucidate key drivers of surface water acidification in glacial lakes in the Czech Republic. Since 1984, the key driver in acidification reversal was sulphate (SO4) concentration (median decrease of −3.58xa0μeqxa0L−1xa0yr−1) which fell in line with reductions in sulphur (S) deposition. Reduction of nitrogen (N) deposition was followed by proportional reduction in nitrate (NO3) leaching although decline in NO3 concentrations was more pronounced at two sites, the Čertovo Lake (CT) and Prášilské Lake (PR) until 2006; only Žďárské pond showed effective catchment N immobilization. Coherent decline of chloride concentration was detected across all sites. The decrease of strong mineral acids was partly compensated by decrease of inorganic aluminium (Alin), especially at sites most acidified in the beginning of observations (ANC1984–1986 between −160 and −90 μeq L−1 at CT, Černé Lake—CN and Plešné lake—PL) and by reductions of base cations and increases of pH. All lakes (CN, CT, PL, PR and LK) moved to the ANC range between −29 and 30 μeq L−1 (2010–2012) where sensitivity of pH to further reductions in acid anions may be expected. Concurrently, charge of weak organic acids (OAs) increased and partly balanced the strong mineral acid decrease as a consequence of (i) significant DOC (dissolved organic carbon) increase (median change of 0.13xa0mgCxa0L−1xa0yr−1 since 1993) and (ii) deprotonation of weak OAs caused by pH rise. Since 2000s, bark beetle induced forest decline accelerated NO3 leaching at most of the catchments (by 200xa0% at LK, PL and PR). However, elevated N leaching was effectively neutralized by base cations (K, Mg, Ca) originating from decaying fresh litter, thus acidification recovery was not reversed, but slowed down. After cessation of NO3 leaching we hypothesise that collapsed tree canopy across catchments (from 12 to 87xa0% compared to 1984) will cause lower total acid input in precipitation (Sxa0+xa0N) and regrowth of vegetation may stimulate higher N immobilization (in biomass and soil); processes which could lead to further increase of ANC and pH, key indicators for biological recovery.

Metal and proton toxicity to lake zooplankton: A chemical speciation based modelling approach

The WHAM-FTOX model quantifies the combined toxic effects of protons and metal cations towards aquatic organisms through the toxicity function (FTOX), a linear combination of the products of organism-bound cation and a toxic potency coefficient for each cation. We describe the application of the model to predict an observable ecological field variable, species richness of pelagic lake crustacean zooplankton, studied with respect to either acidification or the impacts of metals from smelters. The fitted results give toxic potencies increasing in the order H(+) < Al < Cu < Zn < Ni. In general, observed species richness is lower than predicted, but in some instances agreement is close, and is rarely higher than predictions. The model predicts recovery in agreement with observations for three regions, namely Sudbury (Canada), Bohemian Forest (Czech Republic) and a subset of lakes across Norway, but fails to predict observed recovery from acidification in Adirondack lakes (USA).

Assessing recovery from acidification of European surface waters in the year 2010: Evaluation of projections made with the MAGIC Model in 1995

In 1999 we used the MAGIC (Model of Acidification of Groundwater In Catchments) model to project acidification of acid-sensitive European surface waters in the year 2010, given implementation of the Gothenburg Protocol to the Convention on Long-Range Transboundary Air Pollution (LRTAP). A total of 202 sites in 10 regions in Europe were studied. These forecasts can now be compared with measurements for the year 2010, to give a ground truth evaluation of the model. The prerequisite for this test is that the actual sulfur and nitrogen deposition decreased from 1995 to 2010 by the same amount as that used to drive the model forecasts; this was largely the case for sulfur, but less so for nitrogen, and the simulated surface water [NO3(-)] reflected this difference. For most of the sites, predicted surface water recovery from acidification for the year 2010 is very close to the actual recovery observed from measured data, as recovery is predominantly driven by reductions in sulfur deposition. Overall these results show that MAGIC successfully predicts future water chemistry given known changes in acid deposition.

Does stream water chemistry reflect watershedcharacteristics

In this study, we investigated the relationships between stream water chemistry and watershed characteristics (topography—mean altitude and slope; climate—mean annual temperature and precipitation; geology—geochemical reactivity; land cover; inhabitation—population density, road density and number of municipalities). We analyzed the concentrations of the major anions (Cl, F, NO3, SO4, SiO2), cations (Ca, Mg, Na, K, Mn, Fe, Al), trace elements (Li, Sr, Cu), ABS245, TDP (total dissolved phosphorus), pH, and conductivity at 3,220 diverse watersheds covering a wide variety of watershed characteristics in the Czech Republic. We used marginal and partial multivariate analyses to reveal the most important variables. The partial analysis showed that only 14xa0% of the variance could be assigned to a specific factor and that 41xa0% of the variance is shared among the factors, which indicated complex interactions between the watershed characteristics.