Cyanide and heavy metal pollution

Introduction

During the year 2000. two significant pollution waves coming from Romania went along the Tisza and on some courses of its water regime causing tremendous damages in the ecosystem of the Tisza valley, and to the people living here both from economic and mental point of view. Though the two pollutions are common in being in connection with mining, or rather with irresponsible management and ignoring basic environment protection and safety consequences, big differences can be observed in character, measure and effect of the pollutions.

Downflow of water pollutions on the Tisza, survey of measure of pollution and its effects

The fact of both cyanide pollution at the end of January and heavy metal pollution in March were officially reported to the competent Hungarian water conservancy and environment protection organizations by the Kolozsvár Szamos-Tisza Water Conservancy Directorate. As an immediate and direct step in connection with the pollution environment protection inspectorates in agreement with water conservancy directorates ordered secound degree water protection preparedness, they have begun preparations for receiving the pollution. Beside the agreements with water conservancy directorates and companion authorities, they contacted superior organizations, county State Public Health and Medical Officer's Services (ÁNTSZ) and Rescue Directorates too. Before the arrival of the pollution wave status data of the given section of the river have been recorded.

In the period of pollution samplings have been made to record the degree of the pollution, and after the pollution the survey of the measure of death on the given course has been started. Beside this water conservancy directorates tried to lessen the degree of the damage to be expected by water ruling operations.

Samplings have been made on the Hungarian course in the surface registry network sections, and moreover on more important water protection points; in the period of passing of the pollution waves in every two hours in all samplong points, and after the last measure results exceeding basic level data in concentrations of cyanide and heavy metals once a day through 5 days. The collaborators of the competent environment protection inspectorate have taken samples from the streamline of the river according to the Hungarian standard(MSZ ISO5667-6:1995). During this work total cyanide (MSZ 260-30:1992) (distillation method), and concentrations of total and dissolved copper, lead, zinc, cadmium and silver have been measured (MSZ 1484-3:1998) by instrumental analytical methods (AAS, ICP). Measurements have been made by the laboratories of environment protection inspectorates, the Water Quality Protection Institute of VITUKI, the Debrecen University and the Environment Protection Institute of KGI. In the course of hydrobiological investigations qualitative and quantitative analysis of microscopic beings of the river have been made, but investigations have been made on surveying changes ensued in the composition of macroscopic invertebrates too. Beside these, laboratory ecotoxicological tests have also been made, during which the poisoning capacity of the water have been checked by three tests. By Daphnia and guppi (Lebistes) tests the degree of animal death have been determined, by measuring germination capacity and root length growth of white mustard (Sinapis alba) the effect on plants have been studied

in samples taken from the polluted water. After cyanide pollution collecting of fish carcasses has also been started, mainly by the cross closure of the given sections with barges. First qualitative and quantitative data concerning the measure of fish death were supplied by several tons of carcasses in some places. By the above mentioned things we have an exact image about the values of the downflowing pollution, but the evaluation of the mortality of certain plant and animal groups needed/needs a longer period because of more reasons.

Since we have made no samplings either during or after the pollutions, therefore we abstain extendingly from independent evaluation of the data. In the followings data of the pollution and main tendency of their downflow are shown by the available data of environment protection inspectorates, and of the Ministry of Environment Protection and certain researchers and research institutes. Evaluations of the effects of pollutions are also described by data available for us.

The process of cyanide pollution

The first official written Romanian information about the water pollution has arrived to the Upper Tisza Region Environment Protection Inspectorate in 31. January 2000. 18:20. On the operation territory of the inspectorate samplings have been made on 3 points on the Szamos (Csenger, Tunyogmatolcs, Olcsvaapáti), and altogether on 6 points on the Tisza (Vásárosnamény, Lónya, Záhony, Tuzsér, Dombrád, Tiszabercel). The whole Hungarian section of the Szamos have been fully covered with ice in the period of the pollution, there was open water surface only at the mouth and near Lónya. The pollution has arrived into Hungary in 1. February at 15 hours. Peak concentration has reached 32.6 mg/l at 20:30. Contamination wave has culminated with a value of 30 mg/l in 2. February at Tunyogmatolcs, and it reached the region of Olcsvaapáti in the evening. The highest concentration value masured here was 22.5 mg/l. In the Tisza, late in the afternoon cyanide could be traced even in the section near the mouth. An important change, that in consequence of the diluting effect of the Tisza peak concentrations slightly decreased, and together with this the elongation of the pollution has ensued too. The highest measured concentration at Lónya was 13.5 mg/l in 3. February 12:00. Going down the river cyanide concentration further decreased, at Tuzsér in 4. February at 14:00 it was 6.0 mg/l, at Dombrád at 12:00 9.5 mg/l, and at Tiszabercel the same day at 19:30 1.3 mg/l. Contamination wave has left the competence territory of the inspectorate in 6. February. According to the material balance the total amount of cyanide arrived to the territory could be estimated 130-175 tons.

On the basis of the investigations of the Upper-Tisza-Region Environment Protection Inspectorate it can be stated, that on the river section contaminated with cyanide microscopic life of the waters has damaged considerablely. Mortality rate reached 100% on the Szamos in 2. and 3. February; that time the presence of living planctonic organizms could not be shown.

Mortality was 100% within the Csenger section of the Szamos in 2. February between 10:00 and 18:35 hours. Total mortality could be observed at Tunyogmatolcs between 10:00 and 14:30, at Olcsvaapáti between 2. February 14:00 and 3. February 9:15 hours, following the downflow of the contamination wave.

Mortality rate of microscopic organizms in the Vásárosnamény section of the Tisza in 2. February was 10%, at Lónya between 2. and 4. February it was 0-80%, within the same period at Záhony it was 20-90%, between 4. and 9. February at Tuzsér it was 15-80%, between 4. and 6. February at Dombrád it was 30-60% and between 4. and 8. February it varied between 10 and 40%.

During the ecotoxicological investigations according to the small crustacean (Daphnia sp.) test between 1. and 7. February "very strong" and "strong" toxic effect could be registered, (that is test animals died within few hours), while in the following period - between 0.001 and 0.003 mg/l concentrations - water was proved "medium", and "low" toxic. Guppis used for the fish test proved more resistant, "very high" and "high" toxic effects have been proved by concentration values above 1.5 mg/l. This condition lasted in the Szamos till 7. February. Plant germination test was much less sensitive to the pollution, it has shown "strong inhibiting" and "inhibiting" effect on growth only in case of the highest cyanide concentrations. This condition lasted on the Szamos between 1. and 3. February. Concentrations below 5 mg/l showed "slight inhibiting" effect, or they proved ineffective. In consequence of dilution in the Tisza "very strong" toxic effect seemed only between 2. and 4. February according to the small crustacean test. At lower sampling points between 3. and 6. February both by small crustacean and fish tests "very strong" and "strong" toxic effect have been appeared.

Results of ecotoxicological tests are given by changes ensued in test animals during a 48 hours period. According to these:

1. Water is objectionable, if more than 20% of experimental animals die during the examination period;

2. Water is toxic, if more than 50% of experimental animals die during the examination period.

As a function of the exposition period toxicity is classified according to the followings:

A. Water is very highly toxic, if more than 50% of test animals die during 1 hour;

B. Water is highly toxic, if more than 50% of test animals die during 4 hours;

C. Water is medium toxic, if more than 50% of test animals die during 24 hours;

D. Water is slightly toxic, if more than 50% of test animals die during 48 hours;

Between Zemplénagárd and Tiszakeszi on the competence territory of the Environment Protection Inspectorate of Northern Hungary samplings have been made altogether at five sections (Balsa, Tiszatardos, Tiszalök, Polgár, Tiszakeszi). By the measure result of the 1. February basic data cyanide could not be traced in the water of the Tisza in practice.

The fore-part of the contamination wave reached the region of Zemplénagárd in 4. February. The result of cyanide measuring made at Balsa in 5. February at 8:00 signed 12.4 mg/l peak concentration, while az Tiszalök contamination showed a peak of 3.7 mg/l in 6. February at 0:00. At the next sampling point near Polgár the peak could be measured in 6. February at 12:00, the value of which was 3.9 mg/l. In the section between Tiszatardos and Polgár contamination wave reched in about 30 km length. The reason of large scale decrease in cyanide concentration, and that of the elongation of the contamination wave is the diluting effect of the tributaries (bodrog and Sajó), and the more than 10 million m³ water reserved at Tiszalök. Out of these as an effect of the turbines of the hydro-electric plant the major part of free cyanide has eliminated. From this section contamination was present only in the form of cyanide present in metal complexes. Pollution reached the region of Tiszakeszi, the last sampling point of the section, in 7. February with a peak of 2.9 mg/l.

Hydrobiological tests made by the inspectorate within the period of the pollution showed the following results. Number of individuals of algae, of which mainly diatomes (Bacillariophycae) consisted in larger number in comparison with the 1-1.5 million individuals per litre before the pollution, together with the gradual increase in cyanide concentration (from about 0.5 mg/l), this value decreased with 30-50 per cent. It is conspicuous, that diatomes (Bacillariophycae) were less sensitive to the pollution than green algae (Chlorophyta) and heterotrophic flagellate algae (Euglenophyta), which have been totally disappeared from the polluted water body. Among zooplanctonic organizms unicellulars (Ciliata), and small crustaceans (Cladocera, Copepoda) reacted very sensitively, in consequence od the pollution in the section

their total stock has died. Ecotoxicological investigations have been made continuously in this section too, which have been given results similar to those of the upper section. Because of the ice free condition fish carcasses appearing in this section showed mass fish death. For collecting fish carcasses a bed closure have been made with barges below Tokaj. The amount of fish carcasses catched in this section was altogether 13 tons, this however could mean only one fraction of the total amount, since only large bodied fishes could have been collected by this method. Out of this a considerable part of the carcasses have remained in the mud, or they have appeared only in the lower section. These facts were confirmed by investigations made by pulling nets in the bed, and they are supported by carcasses releasing from the bottom in course of cleaning works made at the Tiszalök hydro-electric plant in early summer.

Cyanide in the Eastern and Western Main Channels

In spite of the rise in water level, contamination got into the water of the Eastern Main Channel, and it has reached the Tiszavasvári sluice by 9. February. In consequence of insufficient closure of the sluice water contaminated with cyanide got into the low water section, endangering the Balmazújváros water taking work, that is the water supply system of Debrecen and the neighbouring settlements. Because of this engineers of water conservancy have lifted the water over into the Western Main Channel, and through the Tiszakeszi channel they have brought it back into the Tisza. On the some 30 km section of the Western Main Channel contamination has passed through during 5 days, the peak cincentration value exceeded 1.6 mg/l. It is peculiar, that on the surface of the Tiszavasvári sluice only 0.5 mg/l value could have been measured. Rise can be brought into correlation with decreasing water speed. The Trans-Tisza Environment Protection Inspectorate has also been investigated changes of algal stands

of the Eastern Main Channel, closed from the Tisza, within the period of passing down of contamination wave. Here no symptoms of poisoning caused by cyanide have been observed. Dead individuals of mainly small species have also appeared in low numbers in the contaminated low water section of the Eastern Main Channel. Among them whitefin gudgeon (Gobio albipinnatus) is prominent. Dazed and dead fishes could also be found in the Western Main Channel in the period of the pollution, in the largest number individuals of silver bream (Blicca bjoerkna) and common bream (Abramis brama).

On the middle course of the Tisza between Tiszafüred and Tiszaug betweem 10. and 14. February 2000. investigations have been made by the Middle-Tisza-Region Environment Protection Inspectorate altogether in 6 sections (Tiszafüred, Kisköre, Nagykörű, Szolnok, Vezseny, Tiszaug). By the results of cyanide examinations made in every two hours on the first sampling point at Tiszafüred cyanide peak concentration was 3,4 mg/l in 7. February. On the other points in consequence of the Kisköre barrage cyanide concentration values remained below 3 mg/l. Below Kisköre in 8. February it was 2.2 mg/l, at Nagykörű the same day afternoon (8. February 14:00) 2.4 mg/l, at Szolnok at 22:00 hours 2.3 mg/l, at Vezseny next day at 9:00 also 2.3 mg/l, while at the last sampling point at Tiszaug in 10. February at 0:00 a peak with 2.8 mg/l could be measured. Duration of passing down of contamination wave could be about 36-38 hours.

On the basis of biological investigations made before and during the cyanide pollution it can be stated, that low numbers of species and individuals were characteristic to planctonic life, as in winter time. 70-80% of planctonic organizms died. Stock density of phytoplancton varied between 7 and 103 individuals/ml. Degree of zooplancton death reached 90% in the period of cyanide peak. Letal dose on zooplancton community has been derived 0.01 mg/l, 20-30 times greater than the limit of drinking water, dying however started already at a much lower value.

Here we have to speak about the work of the Middle-Tisza-Region Water Conservancy Directorate too. Befor the arrival of the pollution they have retained more millions m³ water, so with the help of it contamination could be further diluted. The other important result was, that rised water level did not permit contaminated water to get out from the main bed, so plant and animal life of the Tisza Lake has damaged only in 3-5 % according to examination data.

Considerable works have been made in order to keep the drinking water of Szolnok clear, in consequence of which an adequate quality of drinking water could be provided in the period of the pollution too. Beside all these in the period of 2 mg/l cyanide contamination (between 1:00 and 8:00 in 9. February) by the order of the Disaster Prevention Operative Committee no water have been taken from the Tisza.

Examination of the lower section of the Tisza have been made by the Low-Tisza Region Environment Protection Inspectorate taking samples from four sections (Csongrád, Mindszent, Szeged-Tápé, Tiszasziget). Sampling has been started at 20:00 in 9. February. Cyanide appeared at Csongrád at 0:00 in 10. February, and it reached the peak concentration at 12:00 vith a value of 2.9 mg/l. Highest cyanide concentration at Mindszent could be proved at 20:00 hours the same day, the value of which was 2.0 mg/l. Peak value at Szeged was 1.7 mg/l, the contamination reached this value at 8:00 in 11. February. At the last sampling point at Tiszastiget peak concentration could be measured at 12:00, the value of which was 1.49 mg/l. Exposition time varied within certain sections between 50 an 60 hours. The concentration of the pollution was further diluted by the water of Hármas- (Triple) Körös and Maros. The pollution has left the whole territory of Hungary in 13. February.

According to the results of biological investigations plancton has changed primarily qualitatively in comparison with the previous period. Stock-density characteristic to the winter period has not decreased considerably. Flagellate algae (Euglenophyta), flagellate green algae (Phytomonadina) and unicellular green algae (Tetrasporales) disappeared almost at all from the plancton of the Tisza during the pass of the pollution and within the following 12-24 hours. Diatomes (Bacillariophyceae) proved more resistant than the other groups, their proportion within the plancton reached even 100% in some cases. Zooplancton stock has been eliminated almost at all by the passing pollution, living individuals could not be observed even 24 hours after the contamination passed away.

It is worthy of attention, that ecotoxicological test showed total mortality even on the lowermost course of the Tisza both in fisg and small crustacean organizms in the period of peak concentrations. Results of all tests made after the pollution wave passed down were negative.

Evaluation of heavy metals traceable togeter with cyanide

Beside cyanide content, results of measurements of heavy metals dissolved in water (bound in the form of complexes) showed, that copper was present in highest, determining concentration. Beside that, mainly zinc and in lower amount lead and silver concentrations, exceeding the those of natural origin, could be measured. Concentration of copper dissolved in water in the Szamos at Csenger reached 18 mg/l value in course of the 18 hours measuring in 1. February, which is 180 times greater than the hygienic limit (0.1 mg/l). At Olcsvaapáti highest concentration was 16 mg/l. Highest value in the Tisza have been measured at Lónya, where the concentration showed a value of 7400 mg/l. Thanks to dilution - similarly to cyanide - copper concentrations showed also a gradual decrease. These values however, did not show so even change, than cyanide. According to this at Záhony 6,8 mg/l, at Tuzsér 4,2 mg/l, at Dombrád 6,1 mg/l at Tiszabercel 3,1 mg/l, at Balsa 5,9 mg/l, at Tiszalök low water 4,4 mg/l, at Polgár 4,1 mg/l, at Tiszakeszi 3,7 mg/l, at Csongrád 2,4 mg/l, at Mindszent and Szegednél 1,6 mg/l, and at Tiszasziget 1,1 mg/l. By ratios, compared to each other, of cyanide and dissolved copper measured on the lower course, concentration of heavy metal decreased in a higher degree, than that of the cyanide. Highest value of dissolved zinc in the Szamos at Csenger showed 0.95 mg/l, this is about three times greater than the limit (0.3 mg/l) of heavily polluted (5th class) surface water. Going down the Tisza concentration of zinc decreased also gradually, it is characteristic, that already at Lónya (0.1 mg/l) it remained below the 5th class limit. After passing down of the contamination wave dissolved heavy metal concentrations showed values corresponting to the water quality state before the pollution. Dissolved copper concentrations were below the 0.01 mg/l value in the course of measurments in April. Beside the shown results it has to be emphasized again, that these concern metal content dissolved in water, we, however, have no information about the increase of either total (dissolved and linked to floating material) copper and zinc content of the water, or that of heavy metal content of the sediment.

Metal-cyanide complexes, amounting a considerable part of the pollution, dissolving well in water, and beside the chemical composition commonly characteristic to surface waters, they are stable, thereofre they persist unchanged in the water for a longer time. Thanks to this, both cyanide and connecting heavy metals practically left the territory of Hungary in all quantity, they did not accumulate in the sediment. Thanks to water level, the contamination did not touch aquatic habitats of the forebank, and investigation of the nearby wells proved, that pollution did not appear in ground water. In consequence of evaporation, free cyanide content has left the system before it could reach the Middle-Tisza section. By the evidence of material balance difficultly computable because of variable water outputs, characteristic amount of total cyanide on the Hungarian course of the Tisza in the measuring sections was about 100-200 tons.

Process of heavy metal pollution

The fact of heavy metal pollution was signed by the Szamis-Tisza Water Conservancy Inspectorate by fax toward the competent Hungarian environment protection inspectorate at 16 hours in 10. March 2000.In the short informative they reported the fact of pollution, and that steps have been made in order to observe the polluted river course. More detailed report was given by the Romanian authority according to the previous request of the Hungarian party at 9:32 in 11. March. From that time on connection with Ukrainian and Romanian authorities was continuous. In the course of preparations for receiving the pollution from 16:00 in 10. March 2nd grade water quality protection standby has been ordered, which has been executed on all sections of the Tisza in the peroid of passing tdown of the contamination. The arrival of heavy metal pollution was well signed by the change of water colour in the evening hours in 11. March. The first wave of pollution has passed in dawn in 15. March, then in the morning two others, longer lasting than the first one and lesser regarding the load.

According to water chemical investigations of the Upper Tisza Region Environment Protection Inspectorate the quality of the water signed values characteristic to flood seasons. Measurement of heavy metal concentrations in the section entering Hungary at Tiszabecs showed, that polluting material consisted of lead, copper and zinc, in major part linked to very fine grained floating particles of accompanying sterile rocks. Within this section the maximum value of floating material was 1150 mg/l, and the average 700-900 mg/l. Lead quantity present in highest concentration (total lead) showed 2.9 mg/l, the average 1.0 mg/l. Zinc (total zinc) was similar (max. 2.9 mg/l; average 1,0 mg/l), while maximum concentration of total copper was 0.86 mg/l, vhith an average of 0.03 mg/l.These concentrations considerable exceed the values of "heavily polluted" (5th class) water guality class (MSZ 12749:1993), in case of lead with one order. According to different weight of certain metals they occupied determinate places within the contamination wave. In the direction of the flow in the fore-part of the wave zinc and copper fractions of lesser specific density, while in the secound part of the wave lead content was predominate in floating material. This connection is signed by temporal differences of maxima of results of investigations of total lead, copper and zinc, hence the maxima of zinc and copper contamination was followed by the maximum of lead contamination usually with a 4-6 hours delay within the 50-70 km long wave. According to the material balance the amount of lead passing with the first contamination wave at Tiszabecs could be 50 tons, that of copper 20, and that of zinc 70.

Results of biological investigations made by the Environment Protection Inspectorate show the following image. Algal flora of the water was characteristic to the flood season with low numbers of individuals. Fish death could not be observed in the section. Ecotoxicological investigations showed no toxic effect in either case. These results were characteristic to the whole Hungarian course of the Tisza.

Towards the lower section heavy metal content shiwed a decreasing trend, so at Tokaj the peak value of lead concentration has reduced to 0.34 mg/l, that of copper to 0.18 mg/l; at Tiszalök the maximum of lead was 0,34 mg/l, that of zinc was 0.74 mg/l and that of copper was 0.16 mg/l. Increase of the value of floating material was probably the result of the flood (Tokaj 1700 mg/l, Tiszalök 1900 mg/l). At Szolnok as an effect of dammings both floating material content (910 mg/l), and heavy metal content decreased considerably, regarding both maximum values and averages too. (maximum concentrations: lead 0.23 mg/l, zinc 0.44 mg/l, copper 0.22 mg/l). The parameters of all three metals, however, exceeded the limit of heavily polluted water quality class still here. At the Csongrág and the southernmost sampling point, however, heavy metal concentrations remained below these limits. At CSongrág the maximum concentration of lead was 0.19 mg/l, that of zinc at the same place was 0.36 mg/l, while at Tiszasziget the maximum of lead concentration was 0.046 mg/l, and that of zinc was 0.26 mg/l. (Total copper data of the last two sections are not available for us.) Beside the diluting effect of the tributaries decrease of concentration of polluting materials was strengthened by deposition too, this well can be seen from the measure of decreasing certain heavy metal concentrations. According to these, lead with greatest specific density sedimented to the highest degree. First contamination wave has left the territory of Hungary in 19. March.

By sediment analyses made after the contamination has passed away, lead contetn of the sediment has been increased to a concentration around 900 mg/kg at Tiszabecs by floating material of high heavy metal content deposited from the contamination wave. At the same sampling point copper content reached about 500mg/kg, and zinc 1400-1500 mg/kg. These data mean a ten times increase in concentration of heavy metals in comparison with the basic value (lead, copper and zinc concentration of Tisza bed material untouched by the heavy metal pollution wave are 20-70 mg/kg, 20-70 mg/kg and 100-400 mg/kg, respectively).

Heavy metal pollutions have arrived with floods, what has two results. On one hand increase of water speed decreased the grade of sedimentation, on the other hand, however, contaminated water has got into the forebank, and together with this into one part of the forebank dead-beds too. After the withdrawal of the flood the few centimetre thick grey sediment was conspicuous on these places. Heavy metal (primarily lead) accumulated in the forebank getting into plants and animals may have an effect on a longer period. Knowing the bad solution ability of lead, appearance of this heavy metal in the soil as a solution cannot be expected. We also have no information about the life of heavy metal deposited in the bed, because this pollution was rearranged considerably by the next high flood, therefore particular data can be served only by more recent investigations. It is an interesting fact, that heavy metal content investigations of the sediment of dead-beds along the Tisza justifies, that a havaria-like heavy metal pollutions have occurred since the early 19th century.