brechignac_f_desmet_g_eds_equidosimetry_ecological_standardi

TOTAL		–	–	121,269	100,00
		PEAT TOGETHER WITH MYCELIUM OF FUNGI
0-5 cm		20000	4270	85,400	51,34
5-10 cm		50000	527	26,350	15,84
10-15 cm		60000	500	30,000	18,04
15-20 cm		60000	218	13,080	7,86
20-25 cm		70000	100	7,000	4,21
25-30 cm		75000	60	4,500	2,71
including mycelium (in all peat		70	800000	56,000	33,67
layers)
TOTAL		335000	–	166,330	100,00
(peat with fungi mycelium)

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Table 2. Distribution of 137Cs activity in ecosystem of Cladonio-Pinetum, density of ground deposition of 137Cs – 46,4 kBq·m-2 (1,25 Ci·km-2 )

			Mass, kg·ha-1	137Cs specific	137Cs activity,	Part of 137Cs total activity, %
Ecosystem component				activity, Bq·kg-1	MBq·ha-1
Tree canopy			23402	–	9,791	50,56
Wood			8547	126	1,077	5,56
Bark			1155	700	0,809	4,18
Branches			4774	350	1,671	8,63
Annual shoots			150	1210	0,182	0,94
Needles			2079	385	0,800	4,13
Roots thick			6110	730	4,460	23,03
Roots thin			587	1350	0,792	4,09
Juvenile tree layer			5,9	800	0,004	0,026
Undergrowth layer			22	290	0,006	0,031
Grass–dwarf-shrub layer*			*288	*418	0,120	0,62
Lichen layer			1995,8	–	8,197	43,586
Sublayer of epigeous lichens			1995	–	8,192	43,56
Cladina arbuscula ssp. mitis			1400	4180	5,852	30,22
Cladonia uncialis			360	4300	1,548	7,99
Cladonia gracilis			180	4400	0,792	4,09
Cladonia subulata			55	4440	0,244	1,26
Sublayer of epiphytic lichens			0,8	5800	0,005	0,026
(Hypogymnia physodes)
Moss layer			70,5	6800	0,479	2,48
(Polytrichum piliferum)
Layer	of	Macromycetes	4,76	–	0,524	2,708
(fruitbodies)
Cortinarius sanguineus			0,84	160000	0,134	0.69

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Lactarius rufus	0,96	100000	0,096	0,50
Cantharellus cibarius	0,14	11120	0,002	0,008
Siullus variegatus	0,87	79200	0,07	0,36
Siullus bovinus	0,66	58700	0,04	0,20
Boletus badius	0,41	75700	0,03	0,16
Paxillus involutus	0,88	174000	0,153	0,79
TOTAL	–	–	19,367	100,00
	SOIL TOGETHER WITH MYCELIUM OF FUNGI
Forest litter	16400	–	76,310	14,44
Forest litter semi-decomposed	3200	293	0,938	0,18
Forest litter decomposed	13200	5710	75,372	14,26
Mineral soil layers	4935600	–	452,274	85,57
ÍŲ 0-2 cm	228000	1250	285,000	53,92
ÍŲ 2-4 cm	290800	330	95,964	18,16
ÍŲ 4-6 cm	288400	110	31,724	6,00
ÍŲ 6-8 cm	338000	35	11,830	2,24
ÍŲ 8-10 cm	289600	20	5,792	1,10
ÍŲ 10-12 cm	317200	14	4,444	0,84
г 12-14 cm	332400	6	1,994	0,38
г 14-16 cm	363200	5	1,816	0,34
г 16-18 cm	343200	6	2,059	0,39
г 18-20 cm	335200	6	2,011	0,38
г 20-22 cm	315200	9	2,837	0,54
г 22-24 cm	366000	5	1,830	0,35
г 24-26 cm	392000	6	2,352	0,44
г 26-28 cm	362800	3	1,088	0,21
г 28-30 cm	373600	4	1,494	0,28	265

266

including mycelium	1200	–	132,035
(in all soil layers)
TOTAL	4012800	–	528,543	100,00
(soil with fungi mycelium)

*Note: average-weighted data on whole layer.

Table 3. Distribution of 137Cs activity in ecosystem of Molinio-Pinetum, density of ground deposition of 137Cs – 580,0 kBq·m-2 (15,68 Ci·km-2)

Ecosystem component	Mass, kg·ha-1	137Cs specific	137Cs activity,	Part of 137Cs total activity, %
		activity, Bq·kg-1	MBq·ha-1
TREE CANOPY (total)	252552	–	1073,8	49,93
² layer (Pinus sylvestris)	248151	–	1057,5	49,17
Wood	185539	2690	499,1	23,21
Bark	9416	13860	130,5	6,07
Branches alive	15213	10090	153,5	7,14
Branches dried up³	8075	3678	29,7	1,38
Needles	7879	21550	169,8	7,90
Roots	22029	3400	74,9	3,48
²² layer (Betula pubescens)	4401	–	16,3	0,76
Wood	1875	1760	3,3	0,15
Bark	230	5645	1,3	0,06
Branches	1020	6470	6,6	0,31
Leaves	235	11060	2,6	0,12

Roots	1041	2400	2,5	0,12
Moss layer	20802	48120	1001,0	46,55
(Pleurozium schreberi)
Layer of epiphytic lichens	32,8	57920	1,9	0,09
(Hypogymnia physodes)
Grass–dwarf-shrub layer	1518	–	66,7	3,10
Vaccinium myrtillus	1270	40860	51,9	2,41
aboveground phytomass
underground phytomass	217	44300	9,6	0,45
Dryopteris carthusiana	20	162670	3,2	0,15
aboveground phytomass
underground phytomass	11	180000	2,0	0,09
Layer of Macromycetes	2,67	–	7,1	0,33
(fruitbodies)
Suillus variegatus	0,4	2258400	0,9	0,04
Paxillus involutus	1,1	3500000	3,9	0,18
Russula paludosa	0,3	1240000	0,4	0,02
Xerocomus badius	0,35	2800000	1,0	0,05
Lactarius rufus	0,3	2900000	0,9	0,04
Cantharellus cibarius	0,22	160000	0,04	0,00
TOTAL	–	–	2150,5	100,00
	SOIL TOGETHER WITH MYCELIUM OF FUNGI
Forest litter	56911	–	2282,1	49,68

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268

Ferest litter noncomposed	2544	14036	35,7	0,78
Forest litter semi-decomposed	21745	50500	1098,1	23,90
Forest litter decomposed	32622	35200	1148,3	25,00
Mineral soil layers	3438022	–	2311,8	50,32
ÍÅ 0-2 cm	133138	6660	886,7	19,30
ÍÅ 2-4 cm	172018	3270	562,5	12,24
ÍÅ 4-6 cm	211026	1433	302,4	6,58
ÍÅ 6-8 cm	243158	760	184,8	4,02
ÍÅ 8-10 cm	220323	310	68,3	1,49
ÍÅ 10-12 cm	253241	216	54,7	1,19
Å 12-14 cm	272143	140	38,1	0,83
Å 14-16 cm	276190	126	34,8	0,76
Å 16-18 cm	241667	120	29,0	0,63
Å 18-20 cm	234545	110	25,8	0,56
²1 20-22 cm	248182	110	27,3	0,59
²1 22-24 cm	242500	120	29,1	0,63
²1 24-26 cm	240000	100	24,0	0,52
²2Ð 26-28 cm	237391	115	27,3	0,59
²2Ð 28-30 cm	212500	80	17,0	0,37
including mycelium	1200	2258000*	2710,08	58,99
(in all soil layers)
TOTAL	3494933	–	4593,9	100,00
(soil with fungi mycelium)

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The analysis of distribution of the total stock of 137Cs on the components of ecosystem as a whole (with allowance of radionuclide activity in soil and mycelium of mushrooms) also demonstrates the specific geochemical regularities. In particular, the part of 137Cs activity retained by the main forest layer, the tree canopy, in forest ecosystems of Ukrainian Polessye varies in a wide range , from 1,8 % up to 16 % of a total stock of radionuclide in forest ecosystem as a whole. Due to the growth of phytomass of this vegetation layer increase of part of the radionuclide activity retained

by the tree canopy is observed. In ecosystem Molinio-Pinetum the tree canopy contained: for the age to 10 years, 3 % of the total stock of 137Cs of ecosystem, for 30

years 7 %, for 55 years - 15 % [19]. In the Pinus sylvestris tree canopy in automorphic landscapes the observed increase is mainly due to the biomass of trunk wood and bark (40-60 % of a 137Cs sum activity of tree canopy). In hydromorphic landscapes of ombrotrophic bogs in cenosis Ledo-Sphagnetum magellanici the tree canopy of pine retains only 2,03 % of a total stock of 137Cs of ecosystem as a whole, and due to trunk

less than 30 %. In 60-year old forests of cenosis Serratulo-Pinetum pine the tree canopy contained 2-3 % of a total stock of 137Cs of ecosystem and in the oak canopies

of similar age, 6-9 % is due to the greater intensity of radionuclide accumulation [2, 12, 16, 19].

It is necessary to underline that in deciduous forests the intensity of biological migration of 137Cs also increases due to the intensive annual cycling of significant radionuclide activity with litter-fall and its relatively fast decomposition [12].

The layer of undergrowth (living form – shrubs) of the average crown closeness (0,3-0,5) independently from species composition, in forests of Polessye retained only 0,01-0,05 % of a total stock of 137Cs of forest ecosystem; the close indexes are also characteristic for the layer of juvenile trees (up to 0,01 % of the total 137Cs activity of ecosystem) because their insignificant phytomass per unit area.

Grass–dwarf-shrub layer is characterized by various phytomass in forest cenosis in Ukrainian Polessye – from very rarefied (with the sum projective cover 5- 15%) in cenosis Cladonio-Pinetum and Peucedano-Pinetum up to 60 % of projective cover in forested bogs of cenosis Ledo-Sphagnetum magellanici and 95 % in cenosis Molinio-Pinetum. Accordingly a part of the sum of 137Cs activity retained by this layer of vegetation in forests of automorphic landscapes varies from 0,01-0,02 % in cenoses

Cladonio-Pinetum and Peucedano-Pinetum up to 1,0 % in cenosis Molinio-Pinetum sharply increasing up to 2,5-4,0 % in the forests of hydromorphic landscapes as a result of more intensive 137Cs accumulation by all plant species of the layer as well as because essentially smaller relative part of tree canopy in retaining of 137Cs.

Lichen layer consists of two sublayers – epiphytic (on trunks of trees) which part independently from species composition does not exceed 0,01-0,03 % of a sum activity of 137Cs of forest ecosystem, however this sublayer of lichens plays the main role in the interception of 137Cs stemflow. The sublayer of epigeous lichens plays an important role in the formation of phytomass in cenosis Cladonio-Pinetum, where lichens are dominants of undergrowth vegetation of forests, the part of this sublayer reaches 1,5-3 % of a total stock of 137Cs contained in the ecosystem as a whole.

The role of moss layer, the majority of phytocenosis of boreal forests, in retaining of 137Cs by biota is extremely important. As it was shown earlier the part of the sum 137Cs activity circulating in forest ecosystem and retained by layer of

270

green mosses in forests of automorphic landscapes in cenosis Peucedano Pinetum varied from 1% in 10-year's pine forests up to 15% in 50-year's cenosis [19]. In forests of the analyzed automorphic landscapes the part of green moss layer changed from 0,1% in cenosis Cladonio-Pinetum up to 15 % in cenosis Molinio-Pinetum. In hydromorphic landscapes in cenosis Ledo-Sphagnetum magellanici the role of moss layer (from sphagnum mosses) increased up to 35-40% in relation to the total stock of 137Cs content in the forest ecosystem.

Also it should be noted that the role of moss layer is determining, as a biogeochemical barrier, the path of vertical 137Cs migration in all types of forest landscapes – from forest litter to mineral soil layers in automorphic landscapes and from peat litter to peat in hydromorphic ones.

Special attention was paid to studying the role of the mushroom complex in retaining of 137Cs activity in forest ecosystems. During mushroom fruitbodies sampling period the productivity of mushrooms on our experimental plots was low – 6-8 times smaller in comparison with average long-term data on the region [12; 13], therefore in spite of significant 137Cs specific activity in mushrooms fruitbodies, their contribution to retaining of the total 137Cs activity of ecosystem was not so large – 0,1-0,2%. However the part of sum 137Cs activity in mushrooms mycelium deducted from macroblock of soil with forest litter changed from 20 % in forested bog ecosystem of cenosis LedoSphagnetum magellanici up to 40 % in cenosis Molinio-Pinetum.

Thus our calculation has allowed to draw the conclusion that soil (in automorphic landscapes – together with forest litter) contained from 28% of a total stock of radionuclide of ecosystem in cenosis Molinio-Pinetum up to 38 % in cenosis

Ledo-Sphagnetum magellanici and 72% in cenosis Cladonio-Pinetum. The results obtained visibly demonstrate that in conditions when the biological circulation of radionuclide is slow because of unfavorable ecological conditions, as for example in cenosis Cladonio-Pinetum a large part of total stock of radionuclide remains in the soil and is not taken up by vegetation.

It is necessary to underline that the results obtained in this research are in good agreement with data published earlier [5; 19] in which the relative part of soil with forest litter in retaining of 137Cs varied in the limits 60-65 %, including mycelium of mushrooms in this value.

Our research of 137Cs distribution in three forest ecosystems allowed us to draw a conclusion that key components in distribution of this radionuclide in analyzed biogeocenoses were:

in Cladonio-Pinetum – pine tree canopy and epigeous lichen layer;

in Ledo-Sphagnetum magellanici – Sphagnum layer;

in Molinio-Pinetum – pine tree canopy and green moss layer.

So according to the above proposed methodology the heavy metal content was studied in salient key components of ecosystems (table 4).

Analysis of above mentioned data shows that not only 137Cs but also heavy metal content were higher in peak key component. So the distribution of total stock of investigated pollutants should be approximately analogue too. But in other cases essential differences of distribution both in concentrations of pollutants and in its total stock can be observed. Nevertheless, in our mind these regularities of distribution of pollutants are specific and approximately constant in each ecosystem.

Table 4. Average content of 137Cs and heavy metals in some components of different forest ecosystems.

Component	137Cs cont.,		Heavy metal content, mg·kg-1 d.w.
	Bq·kg-1 d.w.	Cu	Zn	Pb	Co
Cladonio-Pinetum
*Pine tree canopy	385±45	1,17±0,22	9,85±1,12	0,51±0,07	0,03±0,004
(needles)
*Epigeous lichen layer	4180±50	3,12±0,38	13,54±1,50	1,48±0,17	0,26±0,03
Soil (mineral 0-2 cm)	1250±140	1,54±0,20	3,00±0,44	1,09±0,21	0,028±0,00
Ledo-Sphagnetum magellanici
*Sphagnum layer (alive	16100±1900	3,40±0,42	21,3±2,75	4,67±0,55	0,52±0,06
part)
*Sphagnum layer (dead	11700±2000	2,45±0,29	28,00±3,42	13,65±1,54	0,83±0,11
part)
Cranberry berries	8600±900	17,75±2,01	12,30±1,23	0,02±0,003	0,01±0,00
Pine tree canopy (needles)2720±300		2,08±0,22	12,04±1,24	0,30±0,05	0,03±0,00
Molinio-Pinetum
*Pine tree canopy	21550±2300	4,52±0,47	8,04±0,95	0,17±0,02	0,003±0,00
(needles)
*Green moss layer	48120±5000	30,14±3,21	19,24±2,22	0,94±0,10	0,17±0,02
Bilberry (shoots)	40860±4000	8,50±1,00	13,92±1,44	0,02±0,003	0,013±0,00
Bilberry (berries)	41000±4200	27,08±3,12	28,84±3,24	0,002±0,00	0,012±0,00
Soil (mineral 0-2 cm)	6660±700	2,08±0,31	4,00±0,43	1,09±0,20	0,03±0,003

Note: key components were marked *.

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