Trends of phosphorus, nitrogen and chlorophyll a concentrations in Finnish rivers and lakes in 1975–2000

During recent decades the amounts of nutrients discharged to Finnish surface waters have markedly decreased. This has been achieved by considerable investments in water protection, which were made mainly to improve municipal and industrial wastewater purification. We investigated whether these water protection measures have decreased phosphorus and nitrogen concentrations in Finnish rivers and lakes. In addition, possible trends in chlorophyll a concentrations in lakes were studied. The data consisted of a total of over 68 000 monitoring results of 22 rivers and 173 lakes (or sub-basins of lakes) with different types of catchment areas. The study period covered the years 1975–2000 and the non-parametric Kendall Tau b and Seasonal Kendall tests were applied for detecting trends. Decreasing nutrient concentration trends were typical in many lakes and rivers earlier polluted by municipal and industrial wastewaters. Increasing nutrient concentration trends were common in smaller rivers and lakes receiving diffuse loading from agriculture. The results show that the investments directed towards wastewater purification have effectively improved the quality of Finnish inland waters. However, no clear effects of decreasing non-point loading were found. Thus, more effective measures should be directed towards decreasing non-point source loading.     

Effects of water sample preservation and storage on nitrogen and phosphorus determinations: implications for the use of automated sampling equipment

The effects of freezing, acidification, refrigeration and extended storage without refrigeration on measured concentrations of forms of nitrogen and phosphorus were assessed in water samples taken from polluted and unpolluted streams in dry and wet weather. Emphasis was placed on likely changes associated with the use of automatic samplers in field conditions. The response of measured nutrient concentrations to different preservation methods and to extended storage without preservation varied widely between samples. For polluted streams where nutrient concentrations were high (ammoniacal nitrogen >0.1 mg l⁻¹; oxidised nitrogen, total Kjeldahl nitrogen, total and filterable phosphorus >1 mg l⁻¹), there was generally little proportional change in nutrients other than ammoniacal nitrogen after up to 6 d of storage without preservation. Where nutrient concentrations were low, up to 90% of ammoniacal nitrogen, 50% of oxidised nitrogen, 84% of total Kjeldahl nitrogen and 67% of total phosphorus was lost after 6 d. If samples cannot be retrieved immediately, automatic samplers should be refrigerated where possible. Acidification is a suitable alternative for preservation of nitrogen. Samples for filterable phosphorus should be filtered as soon as possible after collection. In some circumstances, unpreserved samples may provide an acceptable level of accuracy for evaluation of broad temporal trends or estimation of nutrient loadings.     

Trends of phosphorus,nitrogen and chlorophyll a concentrations in Finnish rivers and lakes in 1975-2000

During recent decades the amounts of nutrients discharged to Finnish surface waters have markedly decreased. This has been achieved by considerable investments in water protection, which were made mainly to improve municipal and industrial wastewater purification. We investigated whether these water protection measures have decreased phosphorus and nitrogen concentrations in Finnish rivers and lakes. In addition, possible trends in chlorophyll a concentrations in lakes were studied. The data consisted of a total of over 68000 monitoring results of 22 rivers and 173 lakes (or sub-basins of lakes) with different types of catchment areas. The study period covered the years 1975-2000 and the non-parametric Kendall Tau b and Seasonal Kendall tests were applied for detecting trends. Decreasing nutrient concentration trends were typical in many lakes and rivers earlier polluted by municipal and industrial wastewaters. Increasing nutrient concentration trends were common in smaller rivers and lakes receiving diffuse loading from agriculture. The results show that the investments directed towards wastewater purification have effectively improved the quality of Finnish inland waters. However, no clear effects of decreasing non-point loading were found. Thus, more effective measures should be directed towards decreasing non-point source loading.     

Recovery of polluted lakes. a swedish research program on the effects of advanced waste water treatment and sewage diversion

In order to elucidate the effects of the effluents from advanced wastewater treatment plants for phosphorus removal, the National Swedish Environment Protection Board during 1972 started a program for analysing the conditions in a number of different recipient lakes. This study of recovery of polluted lakes also includes some recipient lakes from which sewage effluent will be completely diverted. This paper presents the program, some new methods used and the treatment plants and recipient lakes involved. The project. including 18 lakes and 15 sewage treatment plants, is running in cooperation with 13 Provincial Governments and 16 Municipalities. The efficiency of the sewage treatment plants, is continuously monitored by a new method called Minitest, and the nutrient loadings from these plants as well as from other sources are calculated.As the water quality of many recipient lakes showed great variations during the vegetation period (see Fig. 2), a need for a frequent sampling exists in these lakes.In order to simplify the sampling procedure sampling on the shore (after pumping water from the sampling point) has been introduced. Data obtained after analysing samples taken from a boat and samples from the same area taken on the shore after pumping through a 600 m plastic tube showed good agreement (see Table 2).The lake water samples are preserved by freezing, Analyses after rapid thawing showed that this method can be used also when determining from cell material easily leaking ions such as PO₄, NO₃ etc. (see Tables 3 and 4).The sewage treatment plants, the recipient lakes and some background data are presented in Tables 5 and 6. The water quality of the lakes is illustrated with the correlation between chlorophyll A and suspended solids (Fig. 3). The correlation coefficient = + 0–88. The first sign of lake recovery has been observed after an 85 per cent reduction of the waste phosphorus load. Post-precipitation (A1-sulphate) decreased the yearly load from 2000 kg P to 300 kg, which gave a 50 per cent reduction of the P content of the recipient water. Also the chlorophyll values decreased (Table 7).The role of nitrogen and phosphorus as algal growth limiting nutrients has been studied by using an algal assay procedure. N limited the growth of Selenastrum capricornutum in of the samples. In filtered lake water P was the growth limiting nutrient at total-P values below 0–05 mg 1⁻¹. Above 0·1 mg P 1⁻¹ N played the principal role. Between these values the growth was primarily limited by P or N or chelating agents (Fig. 4).     

The effects of organic pollution on benthic organisms near Marseille

A quantitative survey of sublittoral marine organisms was carried out in polluted and unpolluted waters near Marseille (France). Samples from rocky substrates indicate that organic pollution effects have not decreased since earlier surveys.

Studies of beds of Posidonia oceanica, the dominant Mediterranean sea grass, show that its biomass is low in the polluted Gulf of Marseille compared with that in unpolluted bays near Marseille and with data from Malta. Crops were particularly low in shallow water to 15m where it is suggested that grazing by echinoids, whose numbers are probably encouraged by high levels of organic material, could be an important factor limiting growth, as well as other factors such as low underwater irradiance and detergent toxicity.

Along the most polluted coastline near the main sewer outlet at Cortiou, Posidonia was absent and is probably excluded by indirect and direct effects of the effluent. The decline of these sea grass beds has serious implications for sediment stability and the survival of associated biota.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments—II: Features of fatty acids for polluted and unpolluted waters

Fatty acids were analyzed for polluted river waters from the Tokyo area and unpolluted river, brook, reservoir and pond waters from the Ogasawara (Bonin) Islands to elucidate their features for polluted and unpolluted waters. Fatty acids ranging from the carbon chain length of C₈-C₃₄ including unsaturated and branched acids were found with the great predominance of even-carbon numbers and lower molecular weight ranges (C₁₃–C₁₉) in the water samples from the Tokyo area and Ogasawara Islands. It was thus confirmed that no marked changes in fatty acid composition between polluted and unpolluted waters are absent. However, the total contents of the acids (average, 270 ± 120 μg 1⁻¹ at 90% confidence limits) as well as the FAC (fatty acids as carbon)/TOC (total organic carbon, 2.6 ± 0.93%) and FAC/EOC (extractable organic carbon with ethyl acetate, 16 ± 6.7%) of river water samples from the Tokyo area were considerably higher than those of the waters from the Ogasawara Islands (58 ± 29 μg 1⁻¹, 0.79 ± 0.48% and 2.1 ± 0.51%, respectively). These higher values for the Tokyo area should be due to sewage.A filtering method showed that most of fatty acids (>95%) was present in particulate fractions. In addition, the content of free fatty acids was fairly lower than that of combined fatty acids. Further, unsaturated fatty acids were detected only in combined forms both in particulate and dissolved fractions. They are considered to be present as esters in polluted and unpolluted waters.     

Mapping risk of cadmium and lead contamination to human health in soils of Central Iran

In order to map Cd and Pb contamination in the soils of the region of Isfahan, Central Iran, we performed indicator kriging on a set of 255 topsoil samples (0-20 cm) gathered irregularly from an area of 6800 km(2). The measured Cd concentrations exceeded the Swiss guide value in more than 80% of the samples whereas Pb concentrations exceeded the respective guide value only in 2% of the samples. Based on the simulated conditional distribution functions, the probability of exceeding the concentration of Cd and Pb from the specific threshold was computed. The results indicated that in most parts of the region the probability of contamination by Cd is very large (>0.95) whereas it is small (<0.5) for Pb. Based on a misclassification analysis, we chose the probability of 0.45 as optimum probability threshold to delineate the polluted from unpolluted areas for Cd. In addition, we performed a loss analysis to separate risks to human health from potential losses due to remediation costs. Based on this analysis a probability threshold of 0.8 was found to be the optimum threshold for the classification of polluted and unpolluted areas in the case of Cd. Health risks were found to be larger in the western parts of the region. Misclassification analysis was sufficient for risk mapping for Pb as its concentration did not reach risk levels for human health. A probability of 0.7 for Pb was found to be the optimum threshold for the delineation of polluted and unpolluted lands.     

The uptake of heavy metals by epiphytic bacteria on Alisma plantago-aquatica

Bacterial epiphytes on the surface of the fresh-water plant Alisma plantago-aquatica collected from a polluted river were found to be a major factor in contributing to the total metal concentrations of the plant. The removal of epiphytes from the leaf surface resulted in significant reductions in the concentrations of Cr (reduced by 15–50%), Cu (30–35%), Fe, Pb, and Zn (10–50%). While numbers of epiphytes and concentrations of heavy metals increased in samples collected from polluted water compared with from unpolluted water, the fraction of metals held by the epiphytes appeared to remain similar for all samples.     

The abundance, heterotrophic activity and taxonomy of bacteria in a stream subject to pollution by chlorophenols, nitrophenols and phenoxyalkanoic acids

Analysis by HPLC identified 14 individual chlorophenols, nitrophenols and phenoxyalkanoic acids in a small stream in West Yorkshire; concentrations fluctuated markedly over 12 months. Abundance of bacteria (as direct counts and colony-forming units) and heterotrophic activity (as fraction of glucose substrate mineralized) were measured in water and artificial gravel substratum at two sites in this stream. Mean bacterial abundance, and at one site activity, were at least similar to those found in an adjacent unpolluted stream. Sometimes, however, colony-forming units and activity were depressed. Multiple-regression analysis demonstrated relationships between bacteria and pollution-related variables; low pH and nitrophenols (particularly picric acid), were identified as possible causes of bacterial inhibition. Taxonomic investigation of isolates from sediment demonstrated that bacteria in the polluted stream were dominated by Pseudomonas, whereas a wide range of mainly Gram-negative bacteria was present in the unpolluted stream.     

Fluctuating asymmetry in great tit nestlings in relation to diet quality, calcium availability and pollution exposure

Stress during development may cause fluctuating asymmetry (FA), i.e. non-directional and random deviations from perfect symmetry in otherwise symmetrical morphological traits. These deviations affect the phenotypic quality of an individual. We manipulated the diet of nestling great tits, Parus major, to investigate how food quality and quantity affect FA in the length and mass of the outermost tail feathers of great tit nestlings in a polluted and an unpolluted area. High carotenoid diet groups and the control group had higher FA in tail feather length compared to a mealworm-supplemented (low carotenoid) group. This suggests that high carotenoid content in the diet may either directly or indirectly induce higher FA in tail feather length. Calcium is an essential element for birds and important component of feathers. The less calcium there was in the diet, the higher was the FA in tail feather length, which suggests that calcium availability may be an important determinant of the developmental stability of tail feather length. In the control group, in which nestlings were fully dependent upon natural food resources provided by their parents, FA in feather mass was higher in polluted than in unpolluted sites. Diet quality and quantity seemed to differentially affect FA in tail feather length and mass between the polluted and the unpolluted areas. FA in tail feather length in the control group was unaltered by pollution, while FA in tail feather mass was lower in the control group in the unpolluted than in the polluted area. Our study also demonstrates for the first time that the developmental stability of tail feather length and mass are affected by different factors.