Quality of Rivers: Comparison of Hydro-Morphological, Physical-Chemical and Biological Methods

Abstract

The study was performed in five fourth-order tributaries of the Bystrzyca Lubelska River (Eastern Poland, Lublin Upland), differing in the degree of river-bed transformation and level of pollution. Hydro-morphological methods (descriptive method by Ilnicki and Lewandowski - IL, and index method by Oglecki and Pawlat - OP) and biological indices based on the composition of zoobenthos (Diversity - D, and index based on proportions between the density of Oligochaeta and Chironomidae - O/Ch) permitted distinguishing of four classes, from II to V. The distinguishing of only two quality classes (III and IV) was possible by means of physical-chemical methods and by benthic index BMWP_PL. Those two methods seem to show the lowest sensitivity to the spatial variability of the environment quality. The BMWP_PL index was the least sensitive to year-to-year environmental changes, and O/Ch was the most sensitive. Relatively high conformity was obtained between hydro-morphological assessments performed by means of the OP and IL methods. Results obtained by means of these tools weakly corresponded with the physical-chemical assessments. The latter assessments were the most similar to those obtained by means of the BMWP_PL (degree of similarity = 57%) and D (47%) indices, and considerably less in the case of O/Ch (36%). The BMWP_PL and D indices better corresponded with the results of the hydro-morphological assessment performed by means of the IL method than with those performed by means of the OP method while D index showed a reverse pattern. The O/CH index proved useful for the assessment of the degree of organic pollution of the river’s water, but not the sediments.

Statistical analysis of the water pollution indicators pertaining to treated municipal sewage introduced to the river

“…heavy metals, persistent organic pollutants, potential carcinogens, as well as bacteria, viruses and parasites into the receiver [5][6]. As a result, numerous publications appeared in recent years, aimed at developing the river condition assessment systems [3,[7][8][9][10][11][12][13][14][15][16].…”

“…The quality of running waters has been evaluated for a long time on the basis of physicochemical analyses. The main parameters determining the quality of wastewater and receiver waters include BOD5 (5-day Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), pH, TSStot (Total Suspended Solids), as well as the content of nitrogen and phosphorus compounds [5][6][7][8]. It is also known that a complete assessment of river condition is possible only after introducing the aspects of biological assessment [8][9][10]; similarly, as in the case of the treated wastewater quality assessment and wastewater treatment plant efficiency.…”

“…However, as far as the quality assessment of aquatic ecosystems is concerned, the environmental indices systems are increasingly preferred. They enable to evaluate the quality of aquatic environment as a habitat for organismsvarious species of protozoa are commonly used for this purpose [8,[12][13][14][15][16].…”

“…Obviously, the best results of river condition control can be achieved by simultaneously applying all three groups of assessment criteria (hydro-morphological, physicochemical and biological), unfortunately, such an approach is relatively rare [8]. Moreover, studies are usually conducted in terms of presenting new method of evaluation [3,8].…”

“…Obviously, the best results of river condition control can be achieved by simultaneously applying all three groups of assessment criteria (hydro-morphological, physicochemical and biological), unfortunately, such an approach is relatively rare [8]. Moreover, studies are usually conducted in terms of presenting new method of evaluation [3,8]. Much more rarely they are the works aimed at determining the sensitivity of these methods and the degree of agreement and complementarity in the final assessment of river conditions [17][18][19][20].…”