Inorganic residual from kraft or soda pulping separated from green liquor in the chemical recovery cycle.

Toxicity to terrestrial plants

Administrative data

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Not a guideline study.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2004

Materials and methods

Principles of method if other than guideline:

Dregs from KRAFT pulping process were mixed to different types of soil, and seed from different types of plants were planted in the mixtures in order to measure the effects of the dreg addition to germination and growth (height or fresh weight) of the plants.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Inorganic residual from kraft or soda pulping separated from green liquor in the chemical recovery cycle.

EC Number:

923-511-9

IUPAC Name:

Inorganic residual from kraft or soda pulping separated from green liquor in the chemical recovery cycle.

Details on test material:

Dregs from KRAFT pulping process, no composition data.

Test organisms

1

Species:

other: Pinus radiata (Monterey pine)

Plant group:

Gymnospermae (conifers)

2

Species:

other: Eucalyptus globulus

Plant group:

Monocotyledonae (monocots)

3

Species:

other: Oryza sativa, cv. 'Diamante' (rice)

Plant group:

Monocotyledonae (monocots)

4

Species:

other: Lemna minor (duckweed)

Plant group:

Monocotyledonae (monocots)

Study design

Test type:

other: germination, survival, growth

Study type:

laboratory study

Substrate type:

other: combination of natural soil or bark and dregs

Limit test:

no

Total exposure duration:

210 d

Remarks:

Duckweed: 50 days, Rice: 70 days, Monterey pine: 210 days, Eucalyptus: 180 days

Test conditions

Test temperature:

16-28 °C, for duckweed 23-25 °C

pH:

8,81 for duckweed cultures, and 8,58 for 1:1 dregs/organic soil substrates composed for seeding of rice.

Moisture:

No data

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Key result

Species:

other: Pinus radiata

Duration:

210 d

Dose descriptor:

other: growth

Remarks:

The results showed that pine seedlings grown in the presence of dregs were 1.07 times taller than controls.

Effect conc.:

ca. 0.1 other: dregs/soil ratio 1:91:9

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth

Details on results:

The results showed that pine and eucalyptus seedlings grown in the presence of dregs, ash, and fly-ash were taller than controls, while similar levels of primary sludge, brown stock rejects and especially grits caused inhibition in growth. In rice, ashes and primary sludge promoted plant growth while dregs, fly-ash, and grits strongly inhibited germination or caused early chlorosis. The observed growth inhibition may be attributed to the fact that these substrates had the highest pH values, electrical conductivity and Na content. For duckweed, in spite of the initially high pH (>8,5), the highest number of fronds and fresh weight were found in the presence of fly-ash and primary sludge. Ash, brown stock rejects, and especially grits strongly inhibited growth, causing chlorosis and early death. The results for substrates containing dregs are presented in table I-IV.

Reported statistics and error estimates:

The standard error for height and weight was calculated for each species.

Any other information on results incl. tables

Table I. Growth responses of Monterey pine,(Pinus radiata) developing in a substrate consisting of a mixture of dregs and sandy soil

Dregs:soil ratio (v/v)	Germination (%)^a	Plant height (cm) (st. error)^b
0:10	96,9	18,4 (0,65)
1:9	96,9	19,8 (0,65)
2:8	81,3	21,3 (0,70)
3:7	81,3	21,8 (0,67)

^agermination results after 80 days

^bplant growth results after 210 days

 

Table II. Growth responses of eucalyptus (Eucalyptus globulus)developing in a substrate consisting of a mixture of dregs and bark.

Dregs:bark ratio (v/v)	Survival (%)^a	Plant height (cm)^a
1:9	33,3	8,1
2,5:7,5	30,8	13,2
5:5	1,3	1,0

^aresults after 180 days

 

Table III. Growth responses of rice (Oryza sativa) developing in a substrate consisting of a mixture of dregs and organic soil.

Dregs:soil ratio (v/v)	Germination (%)^a	Plant height (cm)^a
1:1	< 5,0 chlorosis	8,0

^aresults after 70 days

 

 

Table IV. Growth responses of duckweed (Lemna minor) developing in a substrate consisting of a mixture of dregs and Hoagland’s medium. Substrate pH 8,81

Dregs:HM (v/v)	Fronds/flask (st.error)^a	Fresh weight (mg) (st.error)^a
2,5:7,5	284,5 (19,2)	399 (32,7)

^aresults after 50 days

 

Applicant's summary and conclusion

Conclusions:

It was concluded for pine and eucalyptus, that no negative effects should be expected from the application of some of the studied residues in low amounts, but that these waste products should not be included in a spreading programme at present without a closer examination and after long-term site experiments.