IMPACT OF MOUNTAINOUS AREAS MANAGEMENT SYSTEM UPON BIOGENES CONTENT IN SURFACE WATERS

Włodzimierz Kanownik
Department of Land Reclamation and Environmental Development, University of Agriculture, Cracow, Poland

ABSTRACT

The paper presents the results of over 6 years research on biogenes concentrations in surface waters originated from 4 measurement and control sections located in the catchment of Trybska Rzeka stream, which is a right-bank tributary of Białka river whose mouth lies on the right shore of Czorsztyn reservoir. The research has been aimed at determining the impact of mountainous lands management system on the biogenes content in the surface waters flowing across the area. Since numerous factors, quite often difficult to identify, can influence the number of biogenes in water, the field studies were conducted in three very small catchments that were similar in terms of physical and geographical, as well as climatic conditions, but the lands differed in the agricultural management systems. An additional research section on Trybska Rzeka watercourse within the built-in area of Trybsz village has been established to determine the influence of village farmstead areas on biogenic contaminants introduced to surface waters via various agents.

The conducted research allowed to conclude that the agricultural management system applied to microcatchments significantly impacts biogenes content in surface waters flowing out from the concerned area. Nitrate nitrogen and phosphates contents are most heavily impacted. It was also found that in mountainous areas grasslands are most effective in reducing nitrogen compounds content in infiltration waters. Settlement areas with inconsistent water and sewage disposal management systems and inappropriately designed facilities for storing sewage and manure contribute gravely to degenerating surface waters.

Key words: surface waters, biogenes, agricultural management, microcatchment.

INTRODUCTION

Physical and geographical as well as climatic conditions prevailing in a catchment are known to shape circulation of both water and matter components it carries across the catchment. Naturally, the smaller the catchment, the more significantly pronounced is the impact of non-climatic factors on water circulation features, thus choosing small and very small agricultural catchments, called microcatchments, for studying water and matter it carries in details [2, 7, 9, 12, 13, 14, 19] has become increasingly popular.

Among numerous contaminants originated from rural areas that migrate into surface waters, nitrogen and phosphorous compounds are found especially hazardous. Threats they pose are mainly related to contaminating water environment with biogenic substances providing a perfect nutrient medium for all algae, including blue-green algae, whose mass development makes water turbid and biological life forms to cease, which leads to waters eutrofication [20]. The process, widely occurring in natural environment, is the most intense in still waters. It is the main threat for retention reservoirs built on rivers, since they are prone to cumulating nutritional elements that under favourable conditions can lead to so called water blooming. Excessive amounts of biogenes in surface waters result mainly from inappropriate agrarian activities. The data quoted by Rogers [16], prove that in USA 90% of total nitrogen and 66% of phosphorus originate from diffused sources of contamination. In Poland, the situation is similar, since according Smoroń estimation [20] the percentage of rural areas contribution to the overall amount of nitrogen and phosphorus in flowing waters reaches respectively 70% and 50%.

European ecology policy has prioritised activities related to reducing biogenic compounds amount originating from diffused contamination sources in 91/676/EWG directive on water protection from contamination with agricultural nitrates. Following Poland's accession to EU, the Ministry for the Environment issued ordinances on criteria for defining waters as sensitive to contamination with nitrogen compounds from agricultural sources [17], as well as on specific requirements for activities programmes aimed at limiting nitrogen runoff from agricultural sources [18].

RESEARCH SCOPE AND METHODOLOGY

Field studies and observations were performed since November 1993 till October 1999 in 4 measurement and control sections selected in the area of Trybska Rzeka catchment located in Polish Spisz. The first three hydrometric sections were carefully checked for the catchment areas they closed to be characterised with similar morphometric, soil and climate parameters, and differ only in the area management system. Thus, two neighbouring catchments were chosen, 74% of one were forests (microcatchment A), whereas the other 2 were typical agricultural areas, nearly free from forests and woodlands (microcatchments B and C). Neither buildings nor other permanent facilities that could be considered as contamination spots are located within the catchments. To determine the impact of contamination spots located in rural settlement areas on the biogenes content in flowing waters, another section was located on Trybska Rzeka catchment main aquifer, namely at 1+350 km, whose area was equal to 7.60 km², some 50 m above the mouth of Czarnogórska Rzeka (Fig. 1).

In the selected sections samples of surface waters have been collected and analysed later at the laboratory of Chair for Land Reclamation and Environmental Development, Agricultural University, Cracow. To ensure that samples were fully representative for the overall period of research and to take into account a random character of biogenes content in water, the samples were collected both once a month in an non-systematic manner, and randomly 2 or 3 times in the selected months, with at least a week internal in-between. The standardised laboratory results created the initial database [1] of concentrations of biogenes dissolved in water, namely for nitrate nitrogen N-NO₃^-, ammonia nitrogen N-NH₄⁺ and phosphates PO₄^3-.

Performed measurements data were processed to obtain statistical parameters relevant for concentrations and checked for the statistical significance of the observed differences between mean concentration values of the studied biogenes at the concerned measurement and control sections.

The analysis of the biogenes concentrations was based on the statistical parameters relevant for the studied population (Table 2). It allows to compare the results for various populations taking into account only the parameters values. The relevant parameters were: location measurements for defining the average size and concentration values distribution (mean value, median and quartiles) and variability measures (range and standard deviation). Analysis of the calculated parameters we obtain a full characteristic of the results, which allows to asses differences likely to occur between the data sets representing concentrations of biogenic components in surface waters under analysis. The comparative analysis has been completed with Box-and-Whisker Plots (Figs 12, 13, 14), which form a rectangle whose height is defined by first (25%) and third (75%) quartile, whereas its width remains free. Inside each rectangle a median was marked The defined rectangle is completed by two segments: one joining the rectangle at the first quartile level with the minimum value of the population, the other connects 3^rd quartile with the maximum one. For 'clearly mathematical reasons' in the performed statistical analysis described above, it was assumed that trace concentrations, i.e. the ones falling below the detection threshold due to the accuracy of the applied laboratory measurements, were recorded as 'zero' concentrations.

CHARACTERISTICS OF THE STUDIED MICROCATCHMENTS

Measurement and control sections to study surface waters were located in the catchment of Trybska Rzeka, a tributary of Białka, which flows into Czorsztyn reservoir built on the Dunajec river in 1997. Administratively the catchment lies within Łapsze Wyżne and Bukowina Tatrzańska communities, in Małopolska voivodship (Fig. 2).

The researched area is located at altitudes higher than 650 m above the sea level and belongs to mountainous areas of Pogórze Spiskie macro-region. The slopes in A, B and C microcatchments areas are average, namely 14.8%, 12.6% and 11.8%, respectively. Their soils are brown ones, with a grain size distribution typical for average and heavy clays or loams, mainly silty loams. The soils are highly acid (pH for top layers determined in KCl was below 4.5), poor or very poor in available components (K₂O below 15 mg.100g^-1, and P₂O₅ below 5 mg.100g^-1). Nitrogen content contribution in soil varied from 0.159% of the overall mass in the ortohumus horizon to 0.065% in the deeper layers. Such soils are of poor porosity and display low filtration coefficient. It concerns mainly firm and packed subsoil systems.

The climate there is of a mountainous type, cool, and very humid. Over the research period particular summers varied in terms of precipitation. Annual total precipitation varied between 761 mm and 992 mm in 1994 and 1996 hydrological years, respectively. Annual mean total precipitation over 6 years period was equal to 861 mm. Mean annual air temperature varied from 4.0°C to 6.7°C for 1996 and 1994, respectively, which yielded the mean value of 5.7°C over the research period.

The smallest of all 3 catchments, A catchment with the area of 0.129 km², was called the `forestial´ one, since forests dominate here (Photo 1). Slopes are exposed to north-west and lie to the east of Trybszanka stream. There is only one VI class watercourse in the catchment, 0.425 km long, a right-bank tributary of Trybszanka (km 1+925). The main spring of the stream lies at the altitude of 792 m above sea level, while its mouth at 751 m above sea level, thus average longitudinal inclination of the riverbed reaches 9.65%. While inspecting the forest the microcatchment, many dead trees were found. Moreover, many coniferous trees lost its green colour of their needles that became yellowish. It can be concluded then that the forest was not cared for properly since such marks of a poor sanitary condition were detected.

Microcatchments B and C agriculturally exploited are located at the eastern slope, to the west of Trybszanka stream (photos 2a and b). In the middle of B microcatchment, whose area is equal to 0.253 km² - that is twice bigger than A microcatchment, flows an watercourse called Trzeci Potok. It is 0.870 km long and its mean longitudinal slope of riverbed equals to 5.63%. It starts at the altitude 788 m above sea level, and its confluence to Trybszanka at km 0+970 is located at 739 m The biggest microcatchment C, of the areas of 0.406 km², has an watercourse called Drugi Potok, a left-bank tributary of Trybszanka, which it flows into at km 0+670. It is a VI class stream, 1.075 km long which has one tributary only - a right creek Bez nazwy (0.605 km long). Both streams flow in parallel towards the east. Bez nazwy creek feeds Drugi Potok at km 0+450. Drugi Potok springs are located at 782 m above sea level Its riverbed mean slope is equal to 5.49%.

a)

b)

The forestial catchment A lies at the highest altitudes. Mean altitude of the area equals to 791 m above sea level with height difference of 76 m. Located at the lowest altitudes is the agricultural microcatchment B, with mean altitude of 779 m above sea level, and slightly higher height difference of 83 m. The C microcatchment - agricultural) with a mean altitude of 766 m above sea level and height difference of 99 m (Figs. 3, 6, 9) lies at the lowest altitude.

In all microcatchments areas of slope ranging from 10 to 18% are prevailing, and in microcatchment A they contribute to nearly 65% of its total area. For microcatchment B such range of slopes covers about 61% of the area, while in C microcatchment 53% (Figs. 4, 7, 10).

All microcatchments are compact, have similar circularity and elongation indices. Their mean values for microcatchment width and water network density are very close. They differ in the area, as well as in the catchment and watershed length. However, the microcatchments are contrastive with regards to their agricultural use, which is confirmed by the value of a forestation index, which for microcatchment A equals 0.74, while for the agricultural microcatchments B and C it practically falls down to zero (Figs. 5, 8, 11). Table 1 presents morphometric features for all microcatchments.

The amount of applied fertilisers, calculated for a clear component for 1 ha of agricultural lands, in the research period reached about 35 kg NPK; it should be noted that fertilising with animal waste (solid and liquid manure) was a regular practice, especially in early spring, right before planting root crops.

Section 4 on Trybska Rzeka stream at its km 1+350, in the built over area of Trybsz village, closes the microcatchment of the area of 7.60 km² and it is located some 50 m above Czarnogórska Rzeka mouth, to make sure that its potential influence on the chemical properties if the studied waters is excluded (Photo 3). The living and farming facilities of Trybsz village make the bottom of the valley, along Trybska Rzeka, to be densely built over with a typical Pogórze Spiskie arrangement. The village was inhabited by 759 people. In 1998 in 107 farms involved in livestock rearing 500 pieces of cattle, 400 sheep, 300 pigs and 50 horses were kept. In the research period sewage and water systems were partly developed in the village. Most of farms had liquid manure and farm waste silos, though frequently either faulty constructed, not sealed properly or deliberately unsealed, or even improperly employed. In the built-in area numerous surface waters contaminant spots were detected (Photo 4a and b).

a)

b)

RESULTS

A comparative analysis of the biogenes content in surface waters flowing out of the mountainous microcatchments under different land agricultural management systems, for the rural areas, has been performed.

In the research it was found that for the collected surface water samples from microcatchments A, B and C nitrate nitrogen (N-NO₃^-) concentration varied from 0.22 mg.dm^-3 to 14.67 mg.dm^-3 for section 4. The highest mean value for N-NO₃^- content, equal to 4.13 mg.dm^-3, was found in water collected at the built-in areas. The respective values for the forestial microcatchment A varied from 0.22 to 8.79 mg.dm^-3. The value averaged over the research period was equal to 3.45 mg.dm^-3, and it was higher by 0.69 mg.dm^-3 than the mean value for agricultural microcatchment B (2.76 mg.dm^-3), where N-NO₃^- concentrations spanned between 0.22 mg.dm^-3 and 13.94 mg.dm^-3, with the standard deviation of 2.664. A surprising result was found while analysing medians. It proved that higher nitrate nitrogen concentrations were observed more frequently in waters from A microcatchment, i.e. the forestial one, than at the remaining 3 sections. The results obtained for water samples from the forestial microcatchment (range - 8.57 mg.dm^-3 and standard deviation - 2.544), proved to be least variable, while the most variable ones were found for section 4 (range - 14.28 mg.dm^-3 and standard deviation - 3.475). For all sections the differences in values higher than the median were greater than for the values smaller than the median (Fig. 12).

Ammonia nitrogen (N-NH₄⁺) content ranged from trace values detected in the agricultural microcatchment B, up to 1.62 mg.dm^-3 in the built-in area of Trybsz village. The lowest concentrations (mean value - 0.43 mg.dm^-3) and variability parameters (range - 1.01 mg.dm^-3 and standard deviation - 0.245) were noted for section 2. The highest amounts of ammonia nitrogen occurred in waters collected in the farm facilities areas (mean value - 0.74 mg.dm^-3). Water samples from forestial microcatchment A, were characterised with the highest variability of values N-NH₄⁺ (range - 1.45 mg.dm ³ and standard deviation - 0.322) (Fig. 13).

Mean concentration of PO₄^3- ions ranged from 0.056 mg.dm^-3 for forestial microcatchment A to 0.275 mg.dm^-3 for section 4. The highest concentration (1.67 mg.dm^-3) was recorded for section 4 and it was few times higher than the maximum values observed in the remaining sections. Water at this place displayed the greatest variability, range value - 1.670 with the standard deviation of 0.224. The results for the rest of the sections were more consistent and they ranged from 0.196 to 0.263 for sections 1 and 2, respectively. Alike nitrate nitrogen concentrations, for all sections the discrepancies in values higher than median were found significantly greater than for the values smaller than it (Fig. 14).

Among many factors influencing the chemical components content in surface waters, the land management system in the catchment is the basic one, in particular the one applied to the lands directly adjacent to the watercourse [3, 6, 10]. To determine whether land management system of the microcatchment impacts the level of biogenic components concentrations in surface waters flowing out of the concerned area, an analysis on equality of the mean values for water contaminants concentrations determined for 4 selected measurement and control sections set at the watercourses, was conducted. The mean values were chosen to carry out the statistical analysis, since they the most reliable parameters to characterise data sets. Here, mean arithmetical values of a sample were analysed. A t-Student's test for not correlated variables was made to check whether the differences between concentrations related to water sampling spots, i.e. to the land management system within the catchment, are significant. A separate analysis was performed for each biogene, by comparing differences between mean values obtained for concentrations at particular sections (Table 3). A significance level a = 0.05 was applied for the test in question. The results of the statistical analysis are presented in Table 4, where absolute values for differences between means and their statistical significance are reported. Values in red correspond to differences that are statistically significant at the level of a = 0.05. The arrows placed by their side indicate the tendency of change. An upward arrow indicates that concentrations in the first section from the pair under analysis, were significantly higher than in the second one, and vice versa.

By analysing concentrations in waters flowing out of the forestial microcatchment A in relation to the ones from agricultural microcatchment B, it was concluded that N-NH₄⁺ concentrations were higher by 40%, whereas phosphates concentrations were found smaller by 35%. Both results were statistically significant. No statistically significant differences were found for biogenes concentrations between the waters from microcatchment A and C. By comparing concentrations for biogenic indices in waters from agricultural microcatchments B and C, it was found that N-NH₄⁺ concentrations were significantly lower, while phosphates concentrations in microcatchment B watercourse were higher, by respective values of 22% and 51%. No significant differences were found between the values for nitrate nitrogen concentrations in particular sections (apart from sections 2 and 4).

The highest number of biogenes was found in waters collected from the creek in the built-in area. The biggest percentage differences were recorded for PO₄^3- concentrations, which for the respective section were higher by 391%, 220% and 382% when compared to section 1, 2 and 3, respectively. Smaller differences, though still statistically significant, occur between ammonia nitrogen concentrations, which for section 4 were higher by 25%, 74% and 36% in relation to section 1, 2 and 3, respectively.

DISCUSSION

The long term research performed at IMUZ [11] on non contaminated spring waters (excluding mineral water sources) in Carpathians, has proven the mean nitrate nitrogen nitrate nitrogen, ammonia nitrogen, and phosphates to vary within 0.7-4.6 mg.dm^-3, 0.04-2.4 mg.dm³ 0.005-0.04 mg.dm^-3, respectively. The results can be assumed to form so called 'zero run-off´ originating from the natural background. Higher content of such components result from inappropriate agricultural, industrial or farming activities of humans. That is of significant importance since, as Taylor [21] claims, to define a water contamination index for biogenes, i.e. fertilising substances, is considerably complex. The substances include natural water ecosystems components, and they cannot be considered as 'contaminants' as long as their content falls below a certain level. It is not until such a level has been crossed, when water quality and thus application qualities deteriorate.

Comparing the data collected and processed in IMUZ with regards to detected concentrations, it was found that surface waters from Trybska Rzeka microcatchment watercourses are exposed to anthropogenic contamination. Such observations were confirmed by Roger [16] and Smoroń [20] whose studied proved the majority of nitrogen and phosphate compounds in surface waters to originate from diffused contamination sources.

A statistical analysis consisting in comparing mean concentrations for contamination indices in waters flowing through the selected sections allowed to detect with t-Student's test for independent variables that the management system applied at the catchment significantly affects (a = 0.05) the content of biogenes odpływających from the catchment area.

According to Kopeć [5] research conducted in Małe Pieniny, the lowest content of nitrogen and phosphorus, namely 1.6 mg.dm^-3 and 0.06 mg.dm^-3, respectively, were observed in waters infiltrating from meadows, even at places with high fertilisation of ca 500 kg NPK per hectare, whereas for waters infiltrating into soils fertilised with half of NPK dose, but cultivated with root crops, the content was reported to reach 10 mg of nitrogen in 1 dm³.

Such research results confirm that grasslands are effective in limiting biogenic substances content in infiltration waters. The contents of ammonia nitrogen (N-NH₄⁺) and nitrate nitrogen (N-NO₃^-) transported with surface waters from agricultural microcatchment B, where grasslands contribute to 71% of the area provide just another evidence. Mean concentration in these waters reached 0.43 and 2.76 mgN.dm^-3, respectively and were the lowest mean values for all 4 water sampling places.

In the presented research the lowest phosphates content (PO₄^3-), at the level of nearly 0.06 mg per 1 litre of water were transported out from the forestial microcatchment A and the agricultural one - C. For another agricultural microcatchment B the respective mean content nearing 0.09 mg.dm^-3, i.e. higher by 0.03 mg.dm^-3 was found. The highest biogenes content were observed in surface waters flowing across farmstead areas, namely 0.74 mg.dm^-3, 4.13 mg.dm^-3 and 0.275 mg.dm^-3 for N-NH₄⁺_, N-NO₃^- and PO₄^3-, respectively. Similar values were reported by Rajda et al. [14, 15] in the research on agricultural microcatchments in Rzyki, Beskid Mały, where mean concentration of 0.71 mg.dm^-3, 4.81 mg.dm^-3 and 0.065 mg.dm^-3 were detected for N-NH₄⁺, N-NO₃^- and PO₄³, while for settlement-agricultural microcatchment in Gaj, Pogórze Wielickie, the respective values of 0.84, 3.26 and 0.09 mg.dm^-3 were found.

In a mountainous microcatchment Grajcarka (Małe Pieniny) Kopacz et al. [4], studied biogenic content related to run-off magnitude. N-NH₄⁺, N-NO₃^-, and PO₄^3- mean content were observed to vary between 0.101-0.181 mg.dm^-3, 0.67-1.08 mg.dm^-3 and 0.053-0.066 mg.dm^-3, respectively in Czarna Woda Creek, and between 0.073-0.253 mg.dm^-3, 0.59-0.98 mg.dm^-3 and 0.060-0.082 mg.dm^-3 in Biała Woda Creek. Nitrogen concentrations in the water were 2-4 times lower than in the studied watercourses of the microcatchments A, B and C. Phosphates concentrations, however, stayed at a comparable level.

Michalczewski and Góralczyk [8] for Brzeźnianka stream in Beskid Wyspowy detected mean PO₄^3- concentration at the level of 0.125 mg.dm^-3, while much higher one for N-NH₄⁺, reaching the value of 2.5 mg.dm^-3. The research on surface rub-off in agricultural areas in the Ohio river microcatchment performed in 1981, showed the phosphate content in flowing out waters to reach 0.04-0.84 mg P.dm^-3 [16].

The lack of significant differences between biogenes concentrations in surface waters flowing out form the forestial microcatchment A and the agricultural one C, can be explained by inappropriate forest management in the microcatchment A. It has led to intensified erosion processes, which accompanied by significant slopes and scarce plant coverage, shaped the amounts of the chemicals washed out from the microcatchment area to surface waters.

High nitrogen concentrations found in the forestial microcatchment A, in some cases higher than in the studied agricultural microcatchments, have been widely confirmed in other papers on the issue studied in mountainous areas. It was noted by i.e. Pawlik-Dobrowolski [11] who highlighted that in Carpathian waters from forestial microcatchments are known to contain significant nitrate content, namely within the limit of 6.9-9.5 mg.dm^-3, which is explainable by mineralization of the organic matter from duff. On the other hand, as reported by Taylor [21], the outflow of biogenic components, especially nitrogen, from mountainous microcatchments (Western Karkonosze), despite no agricultural area occurrence, was higher than from many agricultural microcatchments. The author contributed the effect to highly contaminated atmosphere, exceptionally high precipitation and big water run-off.

The presented research has proved contamination occurring in farmstead areas to be the major reason for poor water quality in rural areas. Biogenes concentrations in surface waters flowing across such areas tend to vary greatly (high values of dispersion measure) that proves water quality to have been heavily impacted by anthropogenic factors. The heavy impact sources consist mainly from spot contamination sources such as unsealed septic tanks, or improperly stored solid and liquid animal waste. Concluded findings have been supported by other research results reported by Sarna and Jarząbek [19] that covered the area of 3 catchments in Pogórze Wielickie, namely a densely packed with farmsteads catchment of the watercourse in Polanka, a Biertowice watercourse flowing across woodlands, and a creek microcatchment in the typically agricultural Czechówka.

CONCLUSIONS

1. Biogenes content in flowing-out surface waters have been found to be impacted by management systems applied in mountainous catchments. The management system in the area affects mainly nitrate nitrogen and phosphates contents. The results have been confirmed, at the significance level a = 0.05, with t-Student test for differences between mean concentrations for water contamination indices.

2. Surprisingly the waters flowing out from the forestial microcatchment, where no fertilisation was applied, have not been found much more beneficial in terms of water quality when confronted with waters from typically agricultural microcatchments. High concentrations of ammonia nitrogen, originating from intense organic matter decomposition taking place in duff, have been attributed to being a major cause of the observed effect. However, no significant differences have been found between biogenes concentrations in waters collected from the forestial microcatchment A and the agricultural one C.

3. The lowest content for both nitrogen forms have been noted in the agricultural microcatchment B, where grasslands constitute a major part of the area management section, namely over 70% of the total area. In mountainous areas grasslands have proven to be most effective in reducing nitrogen compounds migration from the catchment area into surface waters.

4. Low biogenic components contents in surface waters of the agricultural microcatchments result from a correct spatial distribution of lands of different character. Separating arable lands from an watercourse with a wide wasteland strip has been found particularly effective. Due to its protective function such strips of wasteland shall be more notably named as 'ecolands'. Reduced fertilisation of arable lands, which over the last decade has drastically dropped to the value of ca 35 NPK / ha, and prevailing organic fertilisation are also known to result in lower biogenic content.

5. It was concluded from the analysis of the mean biogenes concentrations in waters collected at the agricultural microcatchments B and C that waters flowing out from the area of microcatchment C contained more nitrogen compounds. Most likely it resulted from a greater arable lands percentage in the overall management section for these microcatchments, namely 9.78% for B and 18.17% for C, which due to its character have been heavier and more frequently fertilised than grasslands.

6. The rural farmstead areas were found to contribute most heavily to degradation of surface waters. Areas where water and waste management systems have been disturbed and storage facilities for both solid and liquid animal waste have been inappropriately sealed, were found particularly faulty. The results for concentrations obtained for waters from Trybsz village watercourse (section 4), where the highest biogenes content was detected, provide a direct evidence. Farmstead areas generate high level of dissolved phosphates, whose level tripled or even was found 5 times higher in comparison to the content detected in the same catchment above the farmsteads areas. Sewage system and sewage-waste treatment plants facilities are necessary to be erected in order to recover surface waters quality in the research area. Moreover, the existing liquid and solid manure storage facilities must be checked and restored.

7. Further comprehensive research and studies are required to fully recognise the factors and processes affecting surface waters quality in rural areas.

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The paper constitutes a part of Ph.D. thesis on the influence of agricultural management systems in a mountainous microcatchment upon the content and transport of chemical elements in surface waters.

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