Mobilization of heavy metals from river sediments of Northern Greece by complexing agents

The influence of NTA, EDTA, STPP, Triton X100, PO _inf4 ^sup3 and NO _inf3 ^sup? on the mobilization of Pb, Cd, Cu, Cr and Mn from sediments of two rivers located in Northern Greece was studied. The release caused by all examined complexing agents was higher in deionized water than either Axios or Aliakmon river water due to the lack of competition of Ca and Mg cations with the heavy metals for the studied complexing agents, and the decrease of ionic strength. From all examined agents NTA and EDTA showed the greater mobilization ability. Copper showed the greater tendency for remobilization by all examined agents, (according to the order: EDTA?NTA, Triton X1004 PO _inf4 ^sup3? > NO _inf3 ^sup3? ?STPP) while Cr and Mn the smallest following the orders: NTA, PO _inf4 ^sup3? >> NO _inf3 ^sup? , Triton X1004 EDTA, STPP and STPP > EDTA > NTA > Triton X 100 ? PO _inf4 ^sup3? NO₃, respectively. An increase in mobilization was noticed with an increase of agent concentration and time of shaking.     

Interaction between nitrogen fertilization,rainfall and groundwater pollution in sandy soil

A 2 yr field study on the influence of N fertilization and rainfall on groundwater pollution was carried out in the sandy area of Belgium. The NO _inf3 ^sup? -N and Cl^? content of the groundwater at 0.5, 1.0, 1.5, and 2.0 m depths was monitored every two weeks on a field, grown with barley in 1980 and with maize in 1981. Turnips for cattle feed were grown in between the two crops. The total annual rainfall during the period under study was about 800 mm. The NO _inf3 ^sup? -N content at all depths was at all times above 11.3 mg NO _inf3 ^sup? -N dm^?3, the WHO safe limit. Fluctuation of the NO _inf3 ^sup? -N content occurred mainly at 0.5 and 1.0 m. The concentration at 1.5 and 2.0 m depths was higher most of the time than at 0.5 and 1.0 m. Leaching of NO _inf3 ^sup? -N into deeper layers occurred when there was heavy rainfall. There was no important loss of NO _inf3 ^sup? -N through denitrification at 1.5 and 2.0 m depths.     

The geographical distribution and temporal variations of acidic deposition in Eastern North America

Data from two national precipitation chemistry monitoring networks, and several regional air and precipitation chemistry networks are used to describe some broad-scale features of acidic deposition in eastern North America. In northeastern North America, the coefficient of variation is shown to increase from 10–16% for annual averages to nearly 100% for daily values. There is a strong annual cycle in H⁺, SO _inf4 ^sup= and NH _inf4 ^sup+ deposition and some of the other ions although these cycles are not all in phase. The wet NO _inf3 ^sup? deposition contributes relatively more than SO _inf4 ^sup= to the acidity of snow as compared to rain. Wet deposition is highly “episodic” with about 50% to 70% of the total annual deposition of SO _inf4 ^sup= and NO _inf3 ^sup? accumulating in the highest 20% of the days. Estimates made in various ways indicate that, over eastern North America as a whole, dry deposition is approximately equal to wet for both SO _inf4 ^sup= and NO _inf3 ^sup? . Dry may exceed wet in the high emissions zone but drops to about 20% of the total deposition in more remote areas. Deposition via fog or low cloud impaction is an important input to high elevation forests, but more data are required to quantify the magnitude and regional extent of this.     

Mercury antagonists: Effects of sodium chloride and sulfur group (VIa) compounds on excystment of the brine shrimp artemia

Brine shrimp excystment, although highly resistant, is severely inhibited by mmolar mercuric chloride. The presence of 100 mmolar NaCl largely prevents the toxic response. The chloride effect can be explained if the toxic Hg species, neutral HgCl₂, is converted into HgCl _inf3 ^sup2? and HgCl _inf4 ^sup2? since charged species not likely to penetrate cyst walls. Other Hg antagonists include SO _in3 ^su2? , SeO _inf3 ^sup2? , TeO _inf3 ^sup2? and TeO _inf4 ^sup2? , but not SO _inf4 ^sup2? and SeO _inf4 ^sup2? . The activity of both Te species can be explained by ready reduction of Te(VI) to Te(IV). Significant anti-mercurial effects were seen in mmolar thiols, ethionine and organoselenium compounds. Thiamine and methionine were both active Hg antagonists at 10 to 30 mmolar levels. The activities of S, Se and Cl^? compounds show that both geochemical and physiological modes of defense against and adaptation to high Hg levels exist.     

A method for evaluation of acidic sulfate and nitrate in precipitation

A simple method is presented and used to estimate the portions of SO _inf4 ^sup2? and NO _inf? ^sup3 that contribute to the strong acidity in weekly precipitation samples collected at three NADP sites in the eastern United States. The method assumes that, in general, the difference between SO _inf4 ^sup2? and NH _inf+ ^sup4 represents acidic sulfate and the difference between NO _inf? ^sup3 and soil-derived materials (the sum of Ca²⁺, Mg²⁺, and K⁺) represents acidic nitrate. Acidic sulfate and nitrate are considered to be the predominant source of H⁺ (determined from laboratory pH) in the weekly precipitation samples. Most of the acidity for all three sites was attributed to acidic sulfate. The highest fraction of acidic SO _inf4 ^sup2? to H⁺ wet deposition values was for the east-central Tennessee site (0.95) and the northeastern Illinois site (0.90), and the lowest fraction occurred at the central Pennsylvania site (0.75). The Tennessee site had the greatest acidic fraction of sulfate (0.84) and the Pennsylvania site had the greatest acidic fraction of nitrate (0.59).     

Effects of nitrogen dioxide on selected soil processes

Nitrogen dioxide gas was rapidly absorbed by soil. After a 15 min incubation at 25°C, soil at a moisture content of 16% absorbed 99% of the NO₂ introduced into the gas-phase volume of a closed system. The presence of microorganisms hatl no influence on the rate of absorption of the gas by soil. The absorption of NO₂ by sandy clay loam soil was not an oxygen- or temperature-dependent process nor did it depend upon the moisture content of the soil. These physical factors acquired significance only in determining the initial rate of absorption of the gas and the rate at which NO₂ diffused through the soil. Exposure of soil to NO₂ resulted in substantial increases in the levels of NO _inf2 ^sup? N in the soil. Chemical oxidation of the NO _inf2 ^sup? N resulted in an increase in NO _inf3 ^sup? N levels. During a 14-day incubation, NO _inf2 ^sup? N concentrations in sterile soil exposed to an atmosphere containing 100 μg ml^?1 of NO₂ decreased from 190 μg g^?1 of soil to 105 μg g^?1 with an accompanying increase in NO _inf3 ^sup? N from 2 μg g^? ₁ to 63 μg g^?1 of soil. Nitrogen dioxide severely inhibited the growth of both aerobic and anaerobic asymbiotic N₂-fixing bacteria in soil. After a 48 h incubation at 25°C, soil aggregates exposed to an atmosphere containing 100 μg ml^?1 of NO₂ contained 88% and 98% fewer aerobic and anaerobic N₂-fixing bacteria, respectively. C₂H₂-reduction measurements showed that nitrogenase synthesis and activity in artificial soil aggregates amended with 2% glucose were inhibited by 20% and 48%, respectively, when exposed to atmospheric concentrations of 35 and 3.5 μg ml^?1 of NO₂, respectively.     

Temporal variation in aluminum speciation and concentration during snowmelt

Precipitation samples in Alberta were collected and analyzed monthly from six Alberta Environment stations. Samples were collected with Sangamo samplers and analyzed for the major ions, pH and acidity. The data were tabulated and analyzed for spatial distribution, seasonal variation, temporal trends, ionic character and wet sulphate deposition. The major ionic species in Alberta precipitation are Ca²⁺, SO _inf4 ^sup2? , NH _inf4 ^sup+ and N0 _inf3 ^sup? . The spatial distribution shows a slight decrease in pH from southern Alberta (pH 6.0) to northern Alberta (pH 5.4). The seasonal variation shows higher hydrogen ion content in the summer months (pH 5.4 in summer and pH 5.8 in winter). Temporal trends are not apparent over the five year period investigated. The five year average wet sulphate deposition rate in Alberta is 9.1 kg ha^?1 yr^?1.     

Analysis of airborne particles sampled in the southern Appalachian mountains

Over 3 yr of particulate measurements were made at two high elevation sites in the southern Appalachian Mountains of Tennessee and Virginia. Both dichotomous samplers and filter packs were used to obtain day and night, week-long samples for subsequent elemental and ionic analysis. Total No _inf3 ^sup? (HNO₃ + No _in3 ^sup? ) and SO _inf4 ^sup2? averaged, respectively, 1.1 and 5.0 µg m^?3 at Look Rock, Tennessee and 2.0 and 6.4 µg m^?3 at Whitetop Mountain, Virginia. At Whitetop Mountain, the spring and summer seasons had the highest average SO _inf4 ^sup2? concentrations. Seasonally, total N03 varied little. The diurnal variation of elements and SO _inf4 ^sup2? was small. Only total NO _inf3 ^sup? varied substantially with highest values during the day. The fine fraction (particle diameter < 2.5 µm) accounted for about 67% of the total mass. Fine mass and elemental concentrations were generally higher at Look Rock. The elements comprising the principal mass fraction of the coarse samples (2.5 gm < particle diameter < 10 to 15 µm) were of crustal origin (e.g., Al, Si, Ca, Fe) while the element comprising the principal mass fraction of the fine samples (i.e., S) was of manmade origin. Cluster analysis identified two groups of elements at Whitetop Mountain. These groups, in both the coarse and fine fraction, were associate with a soil and an automobile emission component. At Look Rock, only a soil component was obvious.     

Mesoscale spatial variability of sulfate in air and rainwater at St. Louis

Sulfate concentrations in rainwater and in air measured on four summer days at St. Louis were highly variable, both spatially or temporally. Maximum/minimum ratios of aerosol SO _inf4 ^sup? varied by up to a factor of 9, and those in rainwater by a factor of 3 on the average. Generally, SO _inf4 ^sup? concentration patterns in air and rainwater were similar, and consistent with wind direction and the location of sources. Direct relationships between SO _inf4 ^sup? in air and in water were evident on two of the individual days, but not for all days together. The non-uniformity of the SO _inf4 ^sup? pattern plus consideration of possible sources of SO _inf4 ^sup? suggests that nucleation of SO _inf4 ^sup? particles must be a major cause of S scavenging, with some possible influence from sub-cloud impaction.     

Nitrate reduction coupled with microbial oxidation of sulfide in river sediment

Purpose

Nitrate (NO ₃ ^? ) is often considered to be removed mainly through microbial respiratory denitrification coupled with carbon oxidation. Alternatively, NO ₃ ^? may be reduced by chemolithoautotrophic bacteria using sulfide as an electron donor. The aim of this study was to quantify the NO ₃ ^? reduction process with sulfide oxidation under different NO ₃ ^? input concentrations in river sediment.

Materials and methods

Under NO ₃ ^? input concentrations of 0.2 to 30?mM, flow-through reactors filled with river sediment from the Pearl River, China, were used to measure the processes of potential NO ₃ ^? reduction and sulfate (SO ₄ ^2? ) production. Molecular biology analyses were conducted to study the microbial mechanisms involved.

Results and discussion

Simultaneous NO₃ ^? removal and SO₄ ^2? production were observed with the different NO ₃ ^? concentrations in the sediment samples collected at different depths. Potentially, NO ₃ ^? removal reached 72 to 91?% and SO ₄ ^2? production rates ranged from 0.196 to 0.903?mM?h^?1. The potential NO ₃ ^? removal rates were linearly correlated to the NO ₃ ^? input concentrations. While the SO ₄ ^2? production process became stable, the NO ₃ ^? reduction process was still a first-order reaction within the range of NO ₃ ^? input concentrations. With low NO ₃ ^? input concentrations, the NO ₃ ^? removal was mainly through the pathway of dissimilatory NO ₃ ^? reduction to NH ₄ ⁺ , while with higher NO ₃ ^? concentrations the NO ₃ ^? removal was through the denitrification pathway.

Conclusions

While most of NO ₃ ^? in the sediment was reduced by denitrifying heterotrophs, sulfide-driven NO ₃ ^? reduction accounted for up to 26?% of the total NO ₃ ^? removal under lower NO ₃ ^? concentrations. The vertical distributions of NO ₃ ^? reduction and SO ₄ ^2? production processes were different because of the variable bacterial communities with depth.     

Resistance of the caribou lichen Cladina stellaris (Opiz.) brodo to growth reduction by simulated acidic rain

Natural mats of C. stellaris growing in the subarctic lichen woodlands of northern Québec were treated in a randomized complete block design with solutions of simulated rain at pH 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 and 5.6. These solutions were acidified by addition of mixtures of sulfuric and nitric acids to give both 2 : 1 and 6 : 1 μequivalent ratios of SO _inf4 ^sup= : NO _inf3 ^sup? . After two years of acidification there was no significant effect of either pH or SO _inf4 ^sup= : NO _inf3 ^sup? ratio on the growth of C. stellaris, but thallus discoloration was evident below pH 3.5. After three years of acidification marginally significant (p = 0.05) but erratic depression of growth occurred under the 6 : 1 but not the 2 : 1 acidification regime, especially at pH 4.5 or less. Acid precipitation therefore only very gradually impairs the growth of C. stellaris, and the deleterious effects of acidification may be partially offset by nitrogen enrichment when precipitation is relatively rich in nitrate compared to sulfate ions.     

An estimation of atmospheric deposition input of sulphur and nitrogen oxides to the Kejimkujik watershed : 1979–1987

Daily measurements of the concentrations of major ions in ambient air and in precipitation at Kejimkujik National Park, Nova Scotia, Canada over the period May 1979 to December 1987 are used to estimate the wet, dry and total deposition to the watershed. Variations on three time-scales are apparent. The strongest variation, of up to two orders of magnitude occurs on a day to day basis resulting in a coefficient of variation in the range of 110 to 140%. Deposition is highly episodic with the highest 20% of the daily events accounting for 55 to 60% of the long-term deposition. The most systematic variation is the annual cycle observed for many of the species. The air concentration of SO₂ has the most pronounced cycle with a winter maximum and a summer minimum. The SO _inf4 ^sup= air concentrations show a smaller amplitude and are out-of-phase with SO₂, showing a summer maximum. Air concentrations of HNO₃ and particulate N0 _inf3 ^sup- also have an out-of-phase annual cycle, with a summer maximum and summer minimum respectively. Wet deposition of SO _inf4 ^sup= shows a broad maximum through the summer months, but for NO _inf3 ^sup- no systematic cycle is evident. On an ion equivalent basis, NO _inf3 ^sup- contributes as much as SO _inf4 ^sup= to the acidity of winter precipitation, but only one-third as much in the summer months. Although 8.7 yr is too short a time-scale to establish long term variations with any certainty, there does appear to be an overall downward trend in S concentrations and deposition, but not for N. This is not inconsistent with the trends in the emissions of SO₂ and NO_X in the regions upwind of Nova Scotia. The fraction of the S input to the watershed as dry deposition is estimated to average 22% of the total.     

Precipitation chemistry in Nova Scotia: 1978–1987

More than 1400 precipitation samples were collected weekly from 5 sites in Nova Scotia between 1978 and 1987. High concentrations of H⁺, non-marine SO _inf4 ^sup= (^*SO₄) and NO _inf3 ^sup- were observed in 1978 and 1986. In 1983, concentrations of all three parameters were the lowest in the data record. Fluctuations in emissions for SO₂ are insufficient to account for the variability observed in concentration and deposition values. Mean annual concentrations in 1983 were 13, 16, and 6 ueq L^-1 for H⁺, ^*SO₄, and NO _inf3 ^sup- , respectively. In 1986 the values were 35, 28, and 13 ueq L^-1. Concentrations in 1978 were 31, 38, and 16 ueq L^-1. Average pH of precipitation was 4.61 during the 10 yr study. The two most acidic years were 1979 (4.47) and 1986 (4.46). In 1983, the average pH was 4.89. The ratio (equivalents) of NO _inf3 ^sup- to ^*SO4 was 0.41, so most acidity in the precipitation results from H₂SO₄ However, multiple regression analysis revealed that H⁺ is more sensitive to changes in NO₃-concentrations than ^*SO₄. Ratios of summer (JJA) vs winter (JFM) average concentrations were examined. During summer months, ^*SO₄ and H⁺ were 1.8 times winter values. Summer to winter ratios for NO _inf3 ^sup- and NH _inf4 ^sup+ were 1.4 and 2.5, respectively.     

Adverse Effects of Ammonia on Nitrification Process: the Case of Chinese Shallow Freshwater Lakes

Nitrification is a process in which ammonia is oxidized to nitrite (NO ₂ ^? ) that is further oxidized to nitrate (NO ₃ ^? ). The relations between these two steps and ambient ammonia concentrations were studied in surface water of Chinese shallow lakes with different trophic status. For the oxidations of both ammonia and NO ₂ ^? , more eutrophic lakes generally showed significantly higher potential and actual rates, which was linked with excessive ammonia concentrations. Additionally, both potential and actual rates for ammonia oxidation were higher than those for NO ₂ ^? oxidation in the more eutrophic lakes, while in the lakes with lower trophic status, both potential and actual rates for ammonia oxidation were almost equivalent to those for NO ₂ ^? oxidation. This can be explained by the excessive unionized ammonia (NH₃) concentration that inhibits nitrite-oxidizing bacteria in the more eutrophic lakes. The laboratory experiment with different ammonia concentrations, using the surface water in a eutrophic lake, showed that ammonia oxidation rates were proportional to the ammonia concentrations, but NO ₂ ^? oxidation rates did not increase in parallel. Furthermore, NO ₂ ^? oxidation was less associated with particles in natural water of the studied lakes. Without effective protection, it would be selectively inhibited by the excessive ammonia in hypereutrophic lakes, resulting in NO ₂ ^? accumulation. Shortly, the increased concentrations of ammonia cause a misbalance between the NO ₂ ^? -producing and the NO ₂ ^? -consuming processes, thereby exacerbating the lake eutrophication.     

Effect of an attendant anion on the balance of cations in the soil-solution system with an ordinary chernozem as an example

The effect of different anions on the balance of heavy metal cations in the soil-solution system has been assessed under model laboratory conditions. It has been found that the uptake of the Cu, Zn, and Pb cations by an ordinary chernozem from solutions of different salts is accompanied by the displacement of the exchangeable cations to the solution in the following order: Ca²⁺ > Mg²⁺ > Na⁺ > K⁺. The sum of the displaced exchangeable cations in most cases exceeds the amount of the adsorbed heavy metal cations. According to the effect of the anions on the displacing capacity of the metal cations, the following series are formed: for copper, SO ₄ ^2? ? Cl^? > OAc^? > NO ₃ ^? ; for lead, Cl^? ? NO ₃ ^? > OAc^?; and, for zinc, SO ₄ ^2? ? Cl^? ? OAc^? > NO ₃ ^? .     

Biotic and abiotic processes controlling water chemistry during snowmelt at rabbit ears pass,Rocky Mountains,Colorado, U.S.A.

The chemical composition of snowmelt, groundwater, and streamwater was monitored during the spring of 1991 and 1992 in a 200-ha subalpine catchment on the western flank of the Rocky Mountains near Steamboat Springs, Colorado. Most of the snowmelt occurred during a one-month period annually that began in mid-May 1991 and mid-April 1992. The average water quality characteristics of individual sampling sites (meltwater, streamwater, and groundwater) were similar in 1991 and 1992. The major ions in meltwater were differentially eluted from the snowpack, and meltwater was dominated by Ca²⁺, SO ₄ ^2? , and NO ₃ ^? . Groundwater and streamwater were dominated by weathering products, including Ca²⁺, HCO ₃ ^? (measured as alkalinity), and SiO₂, and their concentrations decreased as snowmelt progressed. One well had extremely high NO ₃ ^? . concentrations, which were balanced by Ca²⁺ concentrations. For this well, hydrogen ion was hypothesized to be generated from nitrification in overlying soils, and subsequently exchanged with other cations, particularly Ca²⁺. Solute concentrations in streamwater also decreased as snowmelt progressed. Variations in groundwater levels and solute concentrations indicate that most of the meltwater traveled through the surficial materials. A mass balance for 1992 indicated that the watershed retained H⁺, NH ₄ ⁺ , NO ₃ ^? , SO ₄ ^2? and Cl^? and was the primary source of base cations and other weathering products. Proportionally more SO ₄ ^2? was deposited with the unusually high summer rainfall in 1992 compared to that released from snowmelt, whereas NO ₃ ^? was higher in snowmelt and Cl^? was the same. The sum of snowmelt and rainfall could account for greater than 90% of the H⁺ and NH ₄ ⁺ retained by the watershed and greater than 50% of the NO ₃ ^? .     

Nitrate removal from ground water — use of a nitrate selective resin and a low concentrated regenerant

A new, strong base, macro-porous anion exchange resin, Amberlite IRA 996, appeared to be more nitrate selective than sulfate selective in treating high nitrate concentrations (18 mg NO _inf3 ^sup? -N L^?1) in potable water. When regeneration is carried out in a closed circuit in which a biological denitrification reactor is incorporated to remove nitrate from the regenerant, regeneration salt requirement and brine production can be minimized. In this combination of ion exchange and biological denitrification, regeneration with 30 g NaHCO₃ L^?1) is possible in 6 hr at a flow rate of 11 BV hr^?1. Accumulation of sulfate in the closed regeneration circuit does not affect the nitrate capacity of the resin.     

Examination of the Dissolved Inorganic Nitrogen Budget in Three Experimental Microbasins with Contrasting Land Cover—A Mass Balance Approach

A long-term hydrological and water chemistry research was conducted in three experimental microbasins differing in land cover: (1) a purely agricultural fertilized microbasin, (2) a forested microbasin dominated by Carpinus betulus (European hornbeam), and (3) a forested microbasin dominated by Picea abies (L.) (Norway spruce). The dissolved inorganic nitrogen (DIN: NH ₄ ⁺ , NO ₂ ^? , NO ₃ ^? ) budget was examined for a period of 3 years (1991–1993). Mean annual loads of DIN along with sulfate SO ₄ ^2? and base cations Ca²⁺, Mg²⁺, Na⁺, K⁺, and HCO ₃ ^? were calculated from ion concentrations measured in stream water, open-area rainfall, throughfall (under tree canopy), and streamwater at the outlets from the microbasins. Comparison of the net imported/exported loads showed that the amount of NO ₃ ^? leached from the agricultural microbasin is ～3.7 times higher (43.57 kg ha^?1?a^?1) than that from the spruce dominated microbasin (11.86 kg ha^?1?a^?1), which is a markedly higher export of NO ₃ ^? compared to the hornbeam dominated site. Our analyses showed that land cover (tree species) and land use practices (fertilization in agriculture) may actively affect the retention and export of nutrients from the microbasins, and have a pronounce impact on the quality of streamwater. Sulfate export exceeded atmospheric rainfall inputs (measured as wet deposition) in all three microbasins, suggesting an additional dry depositions of SO ₄ ^2? and geologic weathering.     

Monitoring and Modeling Nitrate Persistence in a Shallow Aquifer

A modeling study on fertilizer by-products fate and transport was performed in an unconfined shallow aquifer equipped with a grid of 13 piezometers. The field site was located in a former agricultural field overlying a river paleochannel near Ferrara (Northern Italy), cultivated with cereals rotation until 2004 and then converted to park. Piezometers were installed in June 2007 and were monitored until June 2009 via pressure transducer data loggers to evaluate the temporal and spatial variation of groundwater heads, while an onsite meteorological station provided data for recharge rate calculations via unsaturated zone modeling. The groundwater composition in June 2007 exhibited elevated nitrate (NO ₃ ^? ) and chloride (Cl^?) concentrations due to fertilizer leaching from the top soil. The spatial distribution of NO ₃ ^? and Cl^? was heterogeneous and the concentration decreased during the monitoring period, with NO ₃ ^? attenuation (below 10?mg/l) after 650?days. A transient groundwater flow and contaminant transport model was calibrated versus observed heads and NO ₃ ^? and Cl^? concentrations. Cl^? was used as environmental tracer to quantify groundwater flow velocity and it was simulated as a conservative species. NO ₃ ^? was treated as a reactive species and denitrification was simulated with a first order degradation rate constant. Model calibration gave a low denitrification rate (2.5e^?3 mg-NO ₃ ^? /l/d) likely because of prevailing oxic conditions and low concentration of dissolved organic carbon. Scenario modeling was implemented with steady state and variable flow time discretization to identify the mechanism of NO ₃ ^? attenuation. It was shown that transient piezometric conditions did not exert a strong control on NO ₃ ^? clean up time, while transient recharge rate did, because it is the main source of unpolluted water in the domain.     

Influence of Catchment Characteristics and Flood Type on Relationship Between Streamwater Chemistry and Streamflow: Case Study from Carpathian Foothills in Poland

The study aimed to determine the influence of catchment characteristics and flood type on the relationship between streamflow and a number of chemical characteristics of streamwater. These were specific electrical conductivity (SC), pH, the concentrations of main ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO ₃ ^? , SO ₄ ^2? , and Cl^?), and nutrients (NH ₄ ⁺ , NO ₂ ^? , NO ₃ ^? , and PO ₄ ^3? ). These relationships were studied in three small catchments with different geological structure and land use. Several flood types were distinguished based on the factors that initiate flooding and specific conditions during events. Geological factors led to a lower SC and main ion concentrations at a given specific runoff in catchments built of resistant sandstone versus those built of less resistant sediments. A lower concentration of nutrients was detected in the semi-natural woodland catchment versus agricultural and mixed-use catchments, which are strongly impacted by human activity. The strongest correlation between streamflow and the chemical characteristics of water was found in the woodland catchment. Different types of floods were characterized by different ion concentrations. In the woodland catchment, higher SC and higher concentrations of most main ions were noted during storm-induced floods than during floods induced by prolonged rainfall. The opposite was true for the agricultural and mixed-use catchments. During snowmelt floods, SC, NO ₃ ^? , and most main ion concentrations were higher when the soil was unfrozen in the agricultural and mixed-use catchments versus when the soil was frozen. In the case of the remaining nutrients, lower concentrations of NH ₄ ⁺ were detected during rain-induced floods than during snowmelt floods. The opposite was true of PO ₄ ^3? .