Utilization of certain substances for the acceleration of the melting of ice

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Utilization of certain substances for the acceleration of the melting of

ice

Skorik, I. L.

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A f a c t o r of s i g n i f i c a n t economic importance t o Canadian s h i p p i n g i s t h e time t h a t a harbour becomes i c e f r e e i n s p r i n g . In r e c e n t y e a r s , c o n s i d e r a b l e a t t e n t i o n has been given t o t h i s problem. Reports i n d i c a t e t h a t t h e Russians have s u c c e s s f u l l y advanced break-up i n many a r e a s , p a r t i c u l a r l y i n t h e f a r n o r t h , by t h e a p p l i c a t i o n of a s u i t a b l e d u s t . In response t o Canadian i n t e r - e s t i n t h e technique, t h e Snow and I c e S e c t i o n of t h e D i v l s i o n of B u i l d i n g Research has been g i v i n g a t t e n t i o n t o t h e p o s s i b l e

a p p l i c a t i o n of t h i s technique t o Canadian c o n d i t i o n s .

It i s one of' t h e r e s p o n s i b i l i t i e s of t h e Snow and I c e S e c t i o n t o c o l l e c t and make a v a i l a b l e i n f o r m a t i o n r e q u i r e d f o r t h e s o l u t i o n of snow and i c e problems encountered i n e n g i n e e r i n g p r a c t i c e . This t r a n s l a t i o n d e s c r i b e s r e s u l t s obtained from a Russian s t u d y on t h e e f f e c t i v e n e s s of v a r i o u s d u s t i n g m a t e r i a l s f o r advancing t h e break- up of an i c e cover. The paper was t r a n s l a t e d by M r . V.N. Pavloff of t h e T r a n s l a t i o n s S e c t i o n of t h e N a t i o n a l Research Council Library, t o whom t h e D i v i s i o n wishes t o record i t s thanks.

Ottawa R.F. Legget

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Title :

Author :

NATIONAL RESEARCII COUNCIL OF CANADA

Technical Translation 1067

Utilization of certain substances for the acceleration of the melting of ice

(K

voprosu ob ispolfzovanii nekotorykh veshchestv dlya uskoreniya

razrusheniya l t d a ) I.L. Skorik

Reference: Trudy Arkticheskogo i Antarkticheskogo Nauchno Issledovatelfskogo

hstituta, 218: 200-208, 1960

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UTILIZATION OF CERTAIN SUI3STANCES FOR TIE ACCELERATION OF TW NELTING OF ICE

It i s lcnown t h a t t h e t r a n s f o r m a t i o n p r o c e s s of w a t e r i n t o i c e and v i c e v e r s a i s a thermodynamic p r o c e s s involvine; t h e emission o r a b s o r p t i o n of thermal energy. The thawing of i c e which o c c u r s i n n a t u r e i s connected w i t h i n c r e a s e d i n t e n s i t y o f s o l a r r a d i a t i o n . Usually i t b e g i n s a t t h e g r a i n boundaries of i n d i v i d u a l c r y s t a l s of i c e , s i n c e i t i s h e r e t h a t t h e s a l t and b r i n e s o l u t i o n s of t h e s e a i c e a r e c o n c e n t r a t e d . Various s u b s t a n c e s embedded

i n t h e i c e become c e n t r e s of a b s o r p t i o n of s o l a r r a d i a n t energy, which l e a d s t o thawing of t h e i c e . The a c t i o n o f s o l a r r a d i a t i o n promotes m e l t i n g and enlargement o f t h e s e c e n t r e s i n t h e i c e mass and t h e r e b y speeds i t s

d e s t r u c t i o n .

I n o r d e r t o a c c e l e r a t e t h e d e s t r u c t i o n of i c e i t i s n e c e s s a r y t o i n t e n s i f y t h e a b s o r p t i o n of s o l a r r a d i a t i o n a t t h e s u r f a c e as w e l l a s a t c e n t r e s w i t h i n t h e i c e mass i t s e l f . The l a t t e r may be achieved by p a i n t i n g t h e i n t e r n a l m i c r o c a v i t i e s , s a l t n u c l e i , h o l e s and c a p i l l a r i e s w i t h i n t h e i c e w i t h t h e a i d of chemical dyes as w e l l as c e r t a i n n a t u r a l s u b s t a n c e s . A s u i t - a b l y chosen s u b s t a n c e p a i n t e d on t h e i c e s u r f a c e should r a p i d l y p e n e t r a t e t h e i c e mass through t h e s e numerous m i c r o c a v i t i e s w i t h i n t h e i c e s h e e t . If t h i s s u b s t a n c e i s w a t e r - i n s o l u b l e and i s c o l l o i d a l l y d i s p e r s e d , t h e n i t p o s s e s s e s a n e x t e n s i v e s p e c i f i c s u r f a c e which would p r o n o t e t h e a d h e r i n g o f i t p

p a r t i c l e s on t h e walls of t h e i c e p o r e s . T h i s would impede them from b e i n g washed o u t o f t h e i c e s h e e t i n t o , t h e w a t e r below.

A h i g h degree of d i s p e r s i t y o f s u b s t a n c e s s u i t a b l e f o r t h e d e s t r u c t i o n of i c e should d e c r e a s e t h e amount of m a t e r i a l needed f o r d u s t i n g , i n c r e a s e t h e i n t e n s i t y of t h e c o l o u r change produced a t t h e i c e s u r f a c e and promote t h e t r a n s f e r of a c o n s i d e r a b l e p o r t i o n of absorbed s o l a r energy from t h e upper s u r f a c e i n t o t h e i c e mass i t s e l f .

I n o r d e r t o check t h e s e assumptions, experiments were arranged on t h e i c e of Lake Ladoga i n 1952 and 1953. The f o l l o w i n g d u s t i n g a g e n t s were used on t h e i c e : ( 1 ) n a t u r a l sand, ( 2 ) sand dyed w i t h P r u s s i a n b l u e ,

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P r u s s i a n b l u e . The experiments r e v e a l e d t h e marked e f f e c t i v e n e s s of sand dyed w i t h P r u s s i a n b l u e and of P r u s s i a n b l u e i t s e l f which i n v e r y minute q u a n t i t i e s

( 0 . 5

-

1 . 0 d m 2 ) promoted v e r y r a p i d d e s t r u c t i o n o f t h e i c e c o v e r .

Experiments on t h e u t i l i z a t i o n of dyes f o r t h e d e s t r u c t i o n of i c e on Lake Ladoga i n d i c a t e d t h e follor.ring:

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and w i t h sand dyed w i t h P r u s s i a n b l u e , a s w e l l a s with P r u a s i a n b l u e i t s e l f , d e c r e a s e s r e f l e c t i o n o f s o l a r r a d i a t i o n from t h e i c e s u r f a c e and promotes i t s thawing.

2 . D u s t i n g with n a t u r a l sand l e a d s t o thawing of t h e i c e cover c h i e f l y from t h e s u r f a c e . P r u s s i a n b l u e , which p e n e t r a t e s w i t h i n t h e i c e mass, weakens t h e i c e c o v e r t o a much g r e a t e r e x t e n t .

3 .

For e q u a l d e n s i t y of d u s t i n g (400 d m 2 ) t h e e f f e c t i v e n e s s of d e s t r u c - t i o n of i c e depends on t h e i n t e n s i t y w i t h which t h e sand i s dyed w i t h P r u s s i a n b l u e : t h e more i n t e n s e t h e b l u e , t h e more e f f e c t i v e i s t h e d e s t r u c t i o n o f t h e i c e c o v e r .

4 . On i n c r e a s i n g t h e i n t e n s i t y o f d y e i n g of t h e i c e c o v e r w i t h P r u s s i a n b l u e from 0.4 t o 1 . 6 d m 2 t h e d e g r e e of d e s t r u c t i o n of t h e i c e cover i n c r e a s e s o n l y s l i g h t l y .

5.

Dyeing t h e i c e cover w i t h P r u s s i a n b l u e ( 0 . 5 d m 2 ) i s more e f f e c t i v e i n t h e m e l t i n g o f i c e t h a n d u s t i n g t h e i c e c o v e r w i t h n a t u r a l sand (400 d m 2 ) .

The r e s u l t s of t h e s e experiments on t h e a c c e l e r a t i o n o f t h e d e s t r u c t i o n o f i c e by d u s t i n g i t w i t h sand and d y e i n g w i t h P r u s s i a n b l u e have been con- firmed by t h e work of G.N. Yakovlev on t h e s e a i c e of V i l ' k i t s k i i S t r a i t dur- i n g May-June 1952.

In o r d e r t o s t u d y t h e e f f e c t of o t h e r s u b s t a n c e s on i c e , experiments were performed i n Dickson Bay d u r i n g t h e p e r i o d June 2-23, 1953. The a i m of t h e s e experiments was t o s t u d y t h e speed and t h e n a t u r e o f m e l t i n g o f s e a i c e on d u s t i n g w i t h a n i l i n e b l a c k , P r u s s i a n b l u e , dyed and n a t u r a l sand, Cambrian and Dickson c l a y s , c o a l d u s t , c i n d e r s , magnesium and aluminium d u s t , Dutch lamp- b l a c k , calcium c h l o r i d e and calcium phosphate. It was a l s o proposed t o check t h e s t a b i l i t y o f t h e a r t i f i c i a l d y e i n g of sand and i c e i n r e l a t i o n t o A r c t i c c o n d i t i o n s

-

s o l a r r a d i a t i o n , s e a and thaw water, a i r t e m p e r a t u r e , e t c .

The l o c a t i o n o f e x p e r i m e n t a l a r e a s i s shown i n Table I. The d u s t e d a r e a s were arranged in s t a g g e r e d rows. C o n t r o l a r e a s which were n o t d u s t e d were l o c a t e d between t h e d u s t e d s e c t i o n s . In t h e t a b l e t h e d u s t e d a r e a s a r e

numbered, and t h e d e n s i t y of d u s t i n g with v a r i o u s s u b s t a n c e s i s c l e a r l y shown. The e x p e r i m e n t a l s e c t i o n s were

5 -

5

= 25 m2 i n a r e a . Each t e s t v a r i a n t was performed s i n u l t a n e o u s l y on two e x p e r i m e n t a l s e c t i o n s .

The d e n s i t y of d u s t i n g o f t h e i c e w i t h sand (dyed and n a t u r a l ) was every- where t h e same and was e q u a l t o 400 g / m 2 of t h e i c e c o v e r . The sand used was l i g h t c o l o u r Dickson sand, which was dyed with:

( a ) P r u s s i a n b l u e

-

two d e g r e e s o f i n t e n s i t y ( 0 . 5 g and 1.0 g p e r 400 g

o f s a n d )

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For dyeing of t h e sand with P r u s s i a n b l u e , 40 g of potassium f e r r o c y a n i d e were d i s s o l v e d i n 1 0 l i t r e s of cold water. 1 0 kg of sand were soaked with t h i s s o l u t i o n . Next, a s o l u t i o n of 20 g f e r r i c c h l o r i d e i n 1 l i t r e of water was added t o t h e r e s u l t i n g wet mass. The sand t h e r e b y became i n t e n s e l y b l u e i n c o l o u r . The dyed sand was scooped o u t of t h e c o n t a i n e r and poured on matting t o d r y .

For dyeing of t h e sand with a n i l i n e black, 23 g of a n i l i n e were d i s s o l v e d i n 100 m l c o n c e n t r a t e d s u l p h u r i c a c i d . The r e s u l t i n g s o l u t i o n was mixed with 500 m l of water, and while s t i l l h o t was poured i n t o a wooden tub a t t h e bottom of which l a y 10 kg of wet sand. A l l of t h e c o n t e n t s of t h e t u b were thoroughly mixed. The wet sand was cooled, and a s o l u t i o n of 3 0 g potassium bichromate i n 75 m l water was g r a d u a l l y poured i n t o i t w i t h mixing i n such a way t h a t t h e temperature of t h e mixture n e v e r r o s e above

l o 0 .

The r e s u l t i n g d a r k mixture was l e f t o v e r n i g h t i n a c o o l b u i l d i n g , and i n t h e morning a

s o l u t i o n of 40 g potassium bichromate i n 120 m l water was added t o i t by drops and with mixing. Next t h e c o n t e n t s of t h e tub were l e f t f o r 6 hours i n a c o o l p l a c e . The remaining l i q u i d was poured o u t , and t h e sand s e t t l e d a t t h e

bottom of t h e t u b was scooped o u t on m a t t i n g and l e f t t o d r y . The d r y dyed sand d a r k g r a y i n c o l o u r . I f i n s t e a d of 10 kg,

5

kg o f sand were used ( w i t h o u t any o t h e r changes i n procedure), t h e r e s u l t i n g sand was dyed d a r k b l u e

.

The p r e p a r a t i o n of pure a n i l i n e b l a c k and p u r e P r u s s i a n b l u e f o r d i r e c t p a i n t i n g of t h e i c e was undertaken i n t h e same way a s f o r dyeing sand. The o n l y d i f f e r e n c e was t h a t t h e dye came o u t of t h e s o l u t i o n n o t on t h e sand s u r - f a c e b u t on t h e bottom of t h e c o n t a i n e r , whence i t was t a k e n f o r d i s t r i b u t i o n on t h e experimental i c e a r e a s .

Coal d u s t was o b t a i n e d by s i f t i n g f i n e N o r i l t s k c o a l through a s i e v e w i t h a p p e r t u r e s 0.5 mm.

The g r a i n s i z e composition of t h e s u b s t a n c e s used f o r d u s t i n g i c e was determined a c c o r d i n g t o t h e method of Klenova and Avilov a s w e l l ao from s i e v e a n a l y s i s data ( ~ a b l e s I1 and 111).

The e f f e c t o f t h e dyes was determined a c c o r d i n g t o m e l t i n g of t h e i c e cover ( i n r e l a t i o n t o t h e d i f f e r e n c e between dyed and b a r e a r e a s ) . In o r d e r t o s t u d y t h e n a t u r e of t h e d e s t r u c t i o n of i c e caused by t h e v a r i o u s dyes and d u s t s , specimens of i c e were carved o u t of t h e experimental a r e a s and observed. I n t h e course o f t h e o b s e r v a t i o n s t h e a i r temperature v a r i e d from -lo t o +14OC.

A t t h e s t a r t of o b s e r v a t i o n s t h e i c e cover was 160 cm t h i c k .

D i f f e r e n c e s i n t h e m e l t i n g of i c e in t h e e x p e r i m e n t a l a r e a s became e v i d e n t a l r e a d y on t h e second day f o l l o w i n g t h e s t a r t of o b s e r v a t i o n s . D e s t r u c t i o n of t h e i c e was e s p e c i a l l y i n t e n s e i n t h e experimental a r e a s which were dyed w i t h

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Prussian blue and a n i l d n e black and i n those dusted with dyed sand and

N o r i l f s k c o a l c i n d e r s . A t t h e end of observations, when due t o g e n e r a l warm- i n g t h e bare i c e a r e a s were melting j u s t a s i n t e n s e l y , t h e r e l a t i v e thawing of the dusted a r e a s did not i n c r e a s e but, i n a c t u a l f a c t , decreased. In t h i s case, melting of t h e bare i c e a r e a was more rapid due t o i t s higher l o c a t i o n than t h a t of t h e dusted a r e a .

Observed r e s u l t s of t h e melting process a r e l i s t e d in Table N.

It i s c l e a r from Table N t h a t f o r equal d e n s i t y of d u s t i n g , i n s p i t e of i t s l i g h t e r colour, t h e blue Cambrian c l a y promotes melting of i c e more

e f f e c t i v e l y than does t h e rust-brown Dickson c l a y .

Application of Cambrian c l a y with a d e n s i t y of 20

d m 2

i s j u s t a s e f f e c - t i v e on t h e i c e a s d u s t i n g with n a t u r a l sand with a d e n s i t y of 400 g / m 2 .

Although d u r i n g l a t e r observations t h e n a t u r a l sand was found t o be more e f f e c t i v e than t h e Cambrian c l a y i n melting t h e i c e , t h i s was n o t due t o t h e n a t u r e of these m a t e r i a l s but was t h e r e s u l t of e x t e r n a l f a c t o r s (e.g. t h e e f f e c t of snow cover on the experimental a r e a s ) .

By June 23, t h e 21st day of t h e experimental s e r i e s , t h e t e s t a r e a s which were dyed with Prussian blue had melted t o a depth of 50

-

60 cm i n comparison t o t h e l e v e l of t h e c o n t r o l areas; t h e t e s t a r e a s dyed with a n i l i n e black

-

t o a depth of 32

-

34 cm; t h e t e s t a r e a s dusted with sand dyed with Prussian

blue

-

It should be i n d i c a t e d t h a t t h e l a t t e r f o u r experimental a r e a s were almost bare of snow. They were covered with a l a y e r of water 10

-

15

cm t h i c k ,

through which one could s e e the weakened i c e , which resembled a s b e s t o s i n i t s s t r u c t u r e . On studying specimens which were carved o u t of t h i s i c e , i t was found t o c o n s i s t of long, v e r t i c a l c r y s t a l s . P a r t i c l e s of c o a l d u s t were

located on t h e boundary between an upper l a y e r of weakened gray-blue i c e and a lower l a y e r of l i g h t - b l u e f i r m i c e . Numerous small p a r t i c l e s of c o a l had

passed through t h e upper l a y e r of i c e , l e a v i n g i n i t s o many extremely t h i n v e r t i c a l pores ( t r a c e s of downward movement), t h a t the i c e developed a needle- l i k e s t r u c t u r e with a fkrmness somewhere between o r d i n a r y i c e and snow. Hard p a r t i c l e s of c o a l d u s t had p e n e t r a t e d t h e i c e t o a depth of 45

-

47 cm.

S t u d i e s of t h e n a t u r e and speed of t h e d e s t r u c t i o n of i c e i n d i f f e r e n t experimental a r e a s showed t h a t the r a t e of t h e d e s t r u c t i o n of t h e i c e cover

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depends n o t o n l y on t h e n a t u r e of t h e dyes and t h e d e n s i t y of d u s t i n g b u t a l s o on t h e d i s p e r s i t y . The e f f e c t of f i n e l y subdivided m a t e r i a l s i n t h e d e s t r u c - t i o n of i c e was noted by almost a l l of t h e s c i e n t i s t s s t u d y i n g t h e a c c e l e r a t e d thawing of i c e w i t h t h e a i d of fine-grade s u b s t a n c e s .

I f a dye i s by n a t u r e a poor a b s o r b e r of s o l a r r a d i a t i o n b u t e x i s t s i n a s t a b l e s t a t e w i t h a h i g h degree of d i s p e r s i o n , i t s o v e r a l l a b i l i t y t o a b s o r b r a d i a t i o n may be g r e a t e r t h a n t h a t of a dye w i t h g r e a t e r a b s o r p t i v e p r o p e r t y b u t low d i s p e r s i t y . Thus, Dickson c l a y i s more i n t e n s e l y coloured t h a n

Cambrian c l a y , b u t f o r e q u a l d e n s i t y of d u s t i n g i t w i l l absorb l e s s r a d i a t i o n . This phenomenon i s e x p l a i n e d by t h e g r a i n s i z e composition of t h e c l a y s : t h e d i s p e r s i t y of Cambrian c l a y i s c o n s i d e r a b l y h i g h e r t h a n t h a t of Dickson c l a y

a able

11).

The lower r a d i a t i o n a b s o r b i n g a b i l i t y of a n i l i n e b l a c k , which i s d a r k e r i n c o l o u r t h a n P r u s s i a n b l u e , may be e x p l a i n e d from t h e f a c t t h a t p a r t i c l e s of a n i l i n e b l a c k ( a s a r e s i n o u s m a t e r i a l ) r a p i d l y adhere t o g e t h e r forming

l a r g e r masses and t h e r e b y d e c r e a s i n g t h e degree of d i s p e r s i o n . The d i s p e r s i t y of P r u s s i a n b l u e remained p r a c t i c a l l y c o n s t a n t in t h e course of t h e

o b s e r v a t i o n s .

N.T. Chernigovskii, who i n 1949 performed experiments on t h e d e s t r u c t i o n of i c e by t h e r a d i a t i o n method, c o n s i d e r s t h a t " t h e d e s t r u c t i v e e f f e c t of

d u s t i n g with c o a l d u s t and c i n d e r s i s almost t h e same". However, on cornparing t h e c o l o u r a t i o n of c o a l d u s t and c i n d e r l a y e r s , i t i s c l e a r t h a t t h e former has a more i n t e n s e c o l o u r . Consequently, one may e x p e c t t h e d e s t r u c t i v e

e f f e c t of c o a l d u s t t o be g r e a t e r t h a n t h a t of c i n d e r s . I f i n t h e experiments of

N.T.

Chernigovsl.ci1 t h e d e s t r u c t i v e e f f e c t s of b o t h d u s t s were observed t o be e q u a l , t h i s would probably be due t o t h e h i g h d i s p e r s i t y of t h e c i n d e r s compensating f o r t h e l i g h t e r c o l o u r .

Experiments performed i n 1953 r e v e a l e d t h a t t h e m e l t i n g a c t i o n of c o a l d u s t f o r a d e n s i t y of d u s t i n g 20 d m 2 was o n l y s l i g h t l y g r e a t e r t h a n t h e melt- i n g a c t i o n of c i n d e r s f o r a d e n s i t y of d u s t i n g 100 d m 2 , .which i s e x p l a i n e d by t h e r e l a t i v e l y low d l s p e r s i t y of c i n d e r s . F o r e q u a l degree of d i s p e r s i o n and d e n s i t y of d u s t i n g , c o a l d u s t should, t h e r e f o r e , have a m e l t i n g a c t i o n many times g r e a t e r t h a n t h a t of c i n d e r s .

I n t h e s e experiments t h e g r e a t e s t m e l t i n g a c t i o n was observed i n t h e c a s e of dyeing i c e d i r e c t l y w i t h P r u s s i a n b l u e ( 1 d m 2 ) and d u s t l n g w i t h c o a l d u s t

(20 @;/m2). Dusting w i t h c o a l d u s t (10 d m 2 ) and sand dyed a n i l i n e b l a c k ( 1

-

2 g p e r 400 g s a n d ) f o r a d e n s i t y of d u s t i n g 400 d m 2 , a s w e l l as d u s t i n g w i t k

c i n d e r s (100 d m 2 ) and d y e i r ~ g w i t h P r u s s i a n b l u e (0.5 d m 2 ) had a s l i g h t l y weaker d e s t r u c t i v e e f f e c t on t h e i c e . An even l e s s s i g n i f i c a n t e f f e c t i n t h e d e s t r u c t i o n of t h e i c e cover was observed ln t h e c a s e of sand dyed P r u s s i a n

(9)

blue (1 g p e r 400 g sand), n a t u r a l sand and sand dyed a n i l i n e black (1

-

2 g p e r 400 g sand) f o r a d e n s i t y of d u s t i n g 400 d m 2 , a s w e l l a s Ca~nbrian c l a y

( 2 0 d m 2 ) .

The high melting a c t i o n of Prussian blue and coal d u s t may be explained by t h e n a t u r e of these substances (dark c o l o u r ) a s well a s by t h e i r high d i s p e r s i t y . In a l l p r o b a b i l i t y t h e a c t i v e r o l e of c o a l d u s t i n t h e d e s t r u c - t i o n of t h e i c e cover i s a l s o due t o t h e good thermal c o n d u c t i v i t y of i t s p a r t i c l e s . These p r o p e r t i e s of c o a l d u s t d i d i n f a c t favour i t s p e n e t r a t i o n

i n t o t h e i c e t o a depth of 47 cm i n s p i t e of t h e 10

-

15

cm t h i c k l a y e r of thaw water on t h e s u r f a c e of t h e i c e s h e e t .

Conclusions

1. Dusting of t h e i c e s u r f a c e with hard i n s o l u b l e f i n e l y - d i s p e r s e d m a t e r i a l s promotes t h e thawing and d e s t r u c t i o n of t h e i c e .

2. The r a t e of thawing and d e s t r u c t i o n of t h e i c e cover depends on t h e n a t u r e and degree of s u b d i v i s i o n of t h e d i s p e r s e d m a t e r i a l a s well a s on t h e d e n s i t y of d u s t i n g of the i c e s u r f a c e with t h i s substance,

3 . Dyeing of n a t u r a l sand with Prussian blue and a n i l i n e b l a c k (0.5, 1

and 2 g p e r 400 g sand) pronlotes i t s d e s t r u c t i v e e f f e c t on t h e i c e , although t o a l e s s e x t e n t than could be expected on t h e b a s i s of t h e s e p a r a t e e f f e c t s of sand and dye. The d e s t r u c t i v e e f f e c t of dyed sand on i c e Is n o t i n f a c t t h e sum e f f e c t of i t s components. On dyeing t h e sand, the dye s t i c k s t o t h e sand p a r t i c l e s ( t h e r e b y i n c r e a s i n g t h e colour I n t e n s i t y .and r a d i a t i o n absorbed) and a l s o forms dye f i l m s on t h e sand p a r t i c l e s which r e s u l t s i n d e c r e a s i n g t h e d i s p e r s i t y of t h e dye ( t h e r e b y reducing t h e e f f e c t i v e n e s s of t h e dye f o r i n c r e a s i n g absorption of s o l a r r a d i a t i o n of t h e d y e ) .

4. The a c t i o n o f , c o a l d u s t ( p a r t i c l e s i z e l e s s than 0.5 mm) on i c e has s e v e r a l f e a t u r e s d i s t i n g u i s h i n g i t from o t h e r d u s t - l i k e m a t e r i a l s :

( a ) 500 g and even 250 g of c o a l d u s t spread over an i c e s u r f a c e a r e a of 25 m2 destroyed t h e i c e cover more e f f e c t i v e l y than d i d 10 kg of sand.

( b ) t h e c o a l d u s t p e n e t r a t e d t h e i c e t o a depth of 47 cm i n s p i t e of t h e 10

-

15

cm t h i c k l a y e r of water.

5.

I n t h e course of t h e experiment, t h e dye Prussian blue which was applied d i r e c t l y on t h e i c e , a s w e l l - a s - t h a t used f o r dyeing sand, g r a d u a l l y changed colour from blue t o green and even rust-.brown. The dye a n i l i n e black d i d not change i t s colour throughout t h e e n t i r e experiment. Prussian blue was twice as e f f e c t i v e in t h e d e s t r u c t i o n of i c e than was a n i l i n e black when each was applied d i r e c t l y t o t h e i c e s u r f a c e . The a c t i o n of P r u s s i a n blue i n dye-

i n g sand was considerably weaker than t h a t of a n i l i n e black used f o r t h e same purpose.

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6. Since t h e r a d i a t i o n a b s o r p t i v i t y of hard, opaque subdivided m a t e r i a l s depends on t h e i r degree of s u b d i v i s i o n a s much a s on t h e i r colour, i n o r d e r t o promote t h e d e s t r u c t i o n o f i c e i t i s more p r a c t i c a l t o use small q u a n t i t i e s ( s e v e r a l grams p e r s q u a r e metre ) of h i g h l y d i s p e r s i b l e s u b s t a n c e s r a t h e r t h a n l a r g e q u a n t i t i e s of s u b s t a n c e s w i t h low d i s p e r s i t y , e . g . sand. The e x i s t i n g s t a n d a r d s f o r d u s t i n g t h e i c e cover with c o a l d u s t i n o r d e r t o melt channels I n t h e i c e may be decreased up t o s e v e r a l hundred times i f t h e p a r t i c l e s s i z e i s correspondingly decreased.

7. Under A r c t i c c o n d i t i o n s d u s t i n g of t h e i c e s u r f a c e with sand, c o a l c i n d e r s a s w e l l as c o a l d u s t i s g e n e r a l l y performed i n o r d e r t o promote

d e s t r u c t i o n of t h e i c e cover with t h e a i d of s o l a r r a d i a t i o n . The r a d i a t i o n a c t i v i t y o f t h e s e s u b s t a n c e s may be i n c r e a s e d I n two ways:

( a ) By dyeing some of t h e s e m a t e r i a l s , e.g. n a t u r a l sand, with P r u s s i a n blue and a n i l i n e black ( 1

-

2 g p e r 400 g sand) and ( b ) by f u r t h e r f i n e sub- d i v i s i o n of t h e dark-coloured, e a s i l y crumbled n a t u r a l m a t e r i a l a , e.g. c o a l ,

(11)

Table I

k c a t i o n of experimental a r e a s in Dickson Bay

n t- tc\ 0 r-l cd a,

-

k h d cd

:

*

c

a, 0- m Xa

21

n tc\ OCU (U cd .a, h k cd cd t-i

"

₃

P

_a, d- k 9-

s5

U r-l . h 4 r - l c d

(13)

Table

I1

Grain s i z e cornposition of several d i s p e r s i b l e substances,

a s determined

by

the method of Klenova and Avilov

Table

I11

Dispersible

substance

Sand from

Dickson

Is

land

Cambrian clay

Dickson clay

Coal dust

(Noril

' s k

c o a l )

Coal ashes

( N o r i l t s k c o a l )

Grain s i z e composition of several d i s p e r s i b l e substances,

accordlng t o s i e v e a n a l y s i s data

$

Composition

> 1.0 nlm

-

1.1

-

3.2 -

2.7 -

3.9 Dispersible

substance

Coal cinders

(Noril

s k

coal

)

Coal dust

Sand 1.0

-

0.1 mm

94.1 -

6 .

-

6.1

48.6 -

49.9

2.9 -

2.4

$

Composition

0 . 1

-

0.05

mrn

5.69 -

35.6 -

35.9

25.9 -

25.9

20.1 -

19.2

>

2.0

mm

25.56 -

-

2.0

-

1.0 mm

13.19 -

-

0.05 -

0.01 Inrn

-

10.33 -

9.2

41.1 -

41.9

11.4 -

1 . 9

24.9 -

22.3

1.0

-

0.5

mm

11.37

10.54

0.9

< 0.01 mrn

-

8 9 . 4 2 - 9 0 . 1 8

16.8 -

16.1

14.1 -

12.3

52.1 -

56.1

0.25 -

0.10 mn

4.86

45.04

92.4

0.5 -

0.25

rnm

8.16

4.37

0.8

t 0 . 1 0 m i

35.18

38.56

5.69

(14)

Table IV

R e l a t i v e

thawing

of dyed and dusted i c e a r e a s

f o r June 9 and 23, 1953

Dye o r d u s t used

Natural sand

Prussian blue 0.5

g / m 2

Prussian blue 1.0 g / m 2

Sand 400

g / m 2

+

Prussian blue 0.5 g/rn2

Sand 400

g / m 2

+

Prussian blue 1.0

g/m2

Aniline black

1 g/m2

Aniline black

2 e;/'m2

Sand 400

d m 2

+

a n i l i n e black

1 g / m 2

Sand

400

g / m 2

+

a n i l i n e black 2

g / m 2

3,

8 12, 19

11,