ACTION: D.5:

The publication of a book on the sodic lakes of the Carpathian Basin and the possibilities on their restoration

The aim of the action is the summary of ecological and environmental status of the unique sodic pans found in the Carphatian Basin. According to these data, our other aim is to work out a Conservation Management and a strategy for rehabilitation and restoration.

 


Photo: Before the beginning of surveying sodic lakes, a professional conciliation was
held in February 2009 (Photo: János Oláh).

 

In 2009 after getting in contact with the affected professional and manager institutions and civilian organizations we have surveyed all data and materials available about sodic lakes. Having done preparations we have started to do the professional studies of fields. In 2009 from among 200 potencial former alive sodic lakes more than 120 pans, in different conditions (alive and recoverable by conservation), were surveyed for geographical, hydrological, biological and ecological data on-the-spot investigations. Simultaneously, we have started the collection of administrative, utilizing, protection and tourism data, but relevant to this case we are still consulting the competent environmental managements (for example: national park directorates and civilian organizations). From the surveyed areas at their present conditions 93 pans were found suitable in all respects to the minimal ecological criteria system used for sodic pans. These criteria are:

  • at least periodic open water surface
  • the annual average minimum of salinity is 1,5 g/litre
  • the meaningful proportion of sodium and hydrogen-carbonate (minimum 25 equivalent%)
  • presence of indicator living creatures

 


Photo: Field sampling from a sodic lake in May 2009. (Photo: Zoltán Ecsedi).


From the surveyed areas water chemistry examinations were performed on 30 of the sodic pans, too. The sodium-hydrogen-carbonate sodic subtype is the characteristic of The Hungarian Great Plain in the first place, but the territorial distribution of different ioncompound subtypes are rather diversified. Although there are focal points of some subtypes (for example: Na>Mg; SO4>HCO3>Cl in Transdanubia, or Na; HCO3>Cl subtype in Dunavölgyi-síkság), but the presence of certain types can not be connected to limited regions.

 

In addition it should be emphasized that another classification system (for example: white, black lakes etc.) is going to be necessary from the point of view of physical and chemical qualities (turbidity, solute coloured organic substance) of the surveyed sodic pans. The surveyed 93 typical and natural sodic pans found in good or acceptable ecological conditions in the Carphatian Basin are demonstrated in the annexed map.

 

The geological distribution of sodic pans can be found in the table below:

Country

Region

Number of sodic pans

Austria

Fertőzug

31

Hungary

Mezőföld

6

Hungary

Duna-Tisza köze

31

Hungary

Trans-Tiszanian Region

16

Serbia

Vajdaság

9

 

Total:

93

The foregoing surveyed sodic pans’ estimated total extension is 3600-3800 ha.

 

 

 

In 2010: We continued the field survey and data collection of the soda pans, mainly those were visited in 2010 which was not surveyed in 2009 because they dried out very early. All statistics of the survey can be found in the table I. (both 2009 and 2010 survey statistics).

 

table I. The final statistics of the soda pan survey

 

Type of data collection:

Number:

 

Areas checked on the field

312

 

Physical and chemical measurements

327

 

Water sample collection

224

 

Biotic samplings

448

 

Completed field forms

156

 

Type of surveyed sodic pans:

Number:

Extension (ha)

(Semi)Natural sodic pans

86

1909

Modified sodic pans

12

597

Artificial sodic pans

5

126

Total

103

2632

Megjegyzés: a közölt adatok még nem véglegesek, ezért csak tájékoztató jellegűek!

 

It is clearly visible from table I that in 2009 and 2010 a total of 312 (see map) different natural, modified or artificial and historical – nowadays not showing any sodic pan characters – areas were surveyed. The survey will give basic geographical, hydrological, biological, ecological, turistical data which can be all used for nature conservation. From the long term habitat management point of view we made lots of consultations with wardens, national park biologists and land users. Almost 1000 field measurements and data collection was realized. We filled 156 field forms of 156 sodic pans which contains 22.800 data. Besides these about 5.300 data of physical, water chemistry and hydrological plus 6000 zoological (invertebrates) records were collected. From the survey records we created an MS Access data base and a GIS geodatabase.

 


map I. Location of the surveyed areas (319) in the Carpathian Basin of the 2009 and 2010 survey.

 

From all the surveyed areas a total of 86 places show characters of a living (semi) natural sodic pan.

 

Assessed the physical and chemical characteristics

 

Some of the hydrological basic data’s of the (semi) natural sodic pans were summarized in table II. It is visible from the data’s that the sodic pans are generally shallow (average 25 cm) and the average size of open water is 17,8 ha. The average salinity of these sodic pans was 4,5 g/l in the combined samples of 2009-2010. This is 1,5 g/l more than the lowest threshold value for the international quantification of continental hyposalin waters. The salinity has a strong seasonal disparity (hypo-mezo-hyper salyn) on these sodic pans as the original high water level of the spring waters is concentrated by summer or autumn as the pans drying. The average pH (9,3) is characteristically alkaline.

 

table II. Some of the hydrological basic data’s of the (semi) natural sodic pans

 

n=174

Mean

Min.

Max.

Open water (ha)

17,8

1

189,8

Water depth (cm)

25,5

2,0

100,0

Secchi-transparency (cm)

8,2

0,5

>100

Salinity (g/l)

4,5

0,5

60,8

pH

9,3

7,7

10,4

 

Based on the water chemistry examination five different types of sodic pans were found in the Carpathian Basin:

  1. Na - HCO3 (basic type)
  2. Na - HCO3>Cl
  3. Na - HCO3>SO4
  4. Na - SO4/Cl>HCO3/Cl
  5. Na>Mg - HCO3>SO4

 

The basic type of Na - HCO3 was found almost everywhere but the distribution of the other types is variable and cannot be confined to a single area within the Carpathian Basin (although Na>Mg; SO4>HCO3>Cl type was dominant in Transdanubia or Na; HCO3>Cl type in the Dunavölgyi-síkság).

 

In the 86 (semi)natural sodic pans the suspended minerals and the pigments according to our measurements were evenly (47–47%) determining the light-transmitting ability of the water while the portion of the algae in the light absorption was minimal (6%). Based on this, the ‘old’ inventory distinguished ‘white’ and ‘black’ sodic pans. In the ‘white’ sodic pans the minerals while in the ‘black’ sodic pans the pigments were dominating in the light absorption, while in the transitional sodic pans both shared the same. Some sodic pans were completely transparent because they had no minerals or pigments in significant quantities. According to this we suggest the following classification of the sodic pan waters:

• Turbid
• Transitional (turbid and pigmented)
• Pigmented
• Completely transparent

The actual visual quantification of the turbidity is rather straightforward with the Secchi-transparency. It is clearly visible from table II that the Secchi-transparency (ZSecch) of the (semi)natural sodic pans are clearly low (mean: 8,2 cm) but the extremes are highly variable. There are specifically turbid (ZSecch=0,5 cm) and also completely transparent (ZSecch>100 cm) types as well.

 

The examined (semi)natural sodic pans (n=86) were 94% hypertrophic and 6% eutrophic, based on the total phosphorus concentration (international OECD standard). Based on the a-chlorophyll the picture is different as an average 33% is hypertrophic, 20–23% is eu- and mezotrophic, and 9% is oligotrophic.

 


Picture: One of the 86 sodic lakes in the Carpathian Basin (Photo: János Oláh)

 

 

In 2011:  All the living and decaying natural sodic lakes of the Carpathian Basin have been surveyed for data collection. We already managed to draw attention to the vulnerability and importance of this habitat type by the partial presentation of the project’s results at various meetings, nature conservation forums and with publications. More research and targeted nature conservation actions are important to save this special habitat. The final and summarized presentation of the works of the project’s result will be completed with the publications of the book. The actual writing-up of the book has started in the winter of 2010/2011 and will continue until the end of 2012.

 


Picture: Soda pan in the Fertő area of the Carpathian Basin (Photo: János Oláh)

 

In 2012: The intended target of the action has been 75% achieved as all the living and decaying natural sodic lakes of the Carpathian Basin has been surveyed for data collection. The final and summarized presentation of the works of the project’s result will be completed with the publications of the book. In 2012 this book has been 90% completed while having continuous correspondence with the subcontractor

 

In 2013 the editorial work of the book was started by the project manager and office assistant which meant continuous correspondence with the publisher and arranging the translation. The book titled ‘Ecology and Management of Soda Pans in the Carpathian Basin’ was finally printed in late December.