E(‘OTOXI(‘OI-OGY

Comparative

AND

ENVIRONMENTAL

SAFETY

20,

325-342

(1990)

Toxicity of Inorganic Contaminants Released by Placer Mining to Early Life Stages of Salmonids KEVIN

J. BUHL AND STEVEN J. HAMILTON

The acute toxicities of four trace inorganics associated with placer mining were determined. individually and in environmentally relevant mixtures. to early life stages of Arctic grayling (T/r!IMU//II.S urc./ic.m) from Alaska and Montana. coho salmon (Oncnrl7!mrhrr.F kixrfch) from Alaska and Washington. and rainbow trout (Oll~ork!71(,/~11.1. wyki.rc) from Montana. The descending rank order of toxicity to all species and life stages was copper > zinc > lead > arsenic. For each of the three species, sensitivity to the inorganics was greater in juveniles than in alevins or in swim-up fry. Arctic grayling from Alaska were more sensitive than the other species tested, including Arctic grayling from Montana. For Arctic grayling, sensitivity to all four inorganics was significantly greater in swim-up fry from Alaska than in alevins from Montana. and sensitivity to arsenic and copper was signihcantly greater in juveniles from Alaska than in juveniles from Montana. In tests with environmentally relevant mixtures (based on ratios of concentrations measured in streams with placer mining) of these four inorganics. copper was identified as the major toxic component because it accounted for 397% of the summed toxic units of the mixture. and an equitoxic mixture ofthese inorganics showed less-than-additive toxicity. Total and total recoverable copper concentrations reported in five Alaskan streams with active placer mines were higher than the acutely toxic concentrations. either individually or in mixtures. that the authors found to be acutely toxic to Arctic grayling and coho salmon from Alasha. However. caution should be used when comparing our results ohtamed in “clear” water to field situations. because speciation and toxicity of these inorganics may be altered in the presence of sediments suspended by placer mining activities. ‘c I990 Acadcm~c Press. In
216000 g

(61000-110000)

82000 >600000

(75000-141000)

47700

(35000.65000)

197000

(145000-267000)

0.97

g

51300

(43300-60800)

32500

(25300.41600)

1.85

g

61700

(41600-91300)

30900

(21900-43600)

12000

(9200-15600)

>18000

fry 0.34

.c

g

alevin 0.85

XT 1988

(48.6-93.7)

23.9

6

alevin

MT 1986

67.5 (67-126)

0.34

0.85

AK 1985

(1.73-3.84)

0.20

alevin

MT 1988

2.58

(1340.2660)

5140

0.97

(6.9-13.3) (1.87~3.90)

100

414

alevin

9.6 2.70

(3.59-9.81)

>1700

0.85

Lead

46.2

alevin 0.81

Zinc

29.9)

>170

alevin

MT 1987

(42.101) (8.3

alevin

>36000 -c

g

0.97

36000

36000

>36000 g

36000

a source: (Flat-head b Only

AK = Alaska Lake

504

c Xc LC50

Salmon

mortality value

(Clear State in

could

the

State Hatchery.

highest

be calculated

Hatcher-,, Somers.

test

Clear,

Alaska):

MT = Montana

Nontana).

concentration.

because

inverted.

329

concentrarion-mortality

data

were

330

BUHL

AND

HAMILTON

LCsO’sfor juveniles from Alaska and Montana were 5.6- to lO.O-fold for arsenate and 11.1- to 19.1-fold for copper, but only 1.2- to 1S-fold for zinc. Generally, sensitivities to these inorganics were similar in juveniles of different year classesfrom Montana. The only significant difference in sensitivity between juveniles of different year classes from Montana was observed for copper. No comparison can be made for lead because the 96-hr LCSo values were lessthan the range of concentrations tested. However, concentration-mortality inversions occurred during the first 48 hr of exposure, and the lower test concentrations killed 280% of the fish during the last 48 hr of exposure. Arctic grayling alevins of the 1986 year classwere significantly more sensitive to arsenate, copper, and zinc than were alevins of the 1987 or 1988 year class. Fry of Alaska grayling were significantly more sensitive than alevins of Montana grayling to each chemical. Differences in relative sensitivity between fry from Alaska and alevins from Montana were 20.3- to 39.2-fold for arsenate, 2.5 to 13.6-fold for copper, >3.0fold for lead, and 5.0- to 9.3-fold for zinc. Juvenile coho salmon were significantly more sensitive than alevins to arsenate and lead, but these two life stageswere equally sensitive to copper and zinc (Table 3). Sensitivity to copper in juvenile coho salmon was significantly greater in fish from Washington than in those from Alaska. However, 96-hr LCsO’sfor alevins were not significantly different from those ofjuveniles from either source. Coho salmonjuveniles from both sourceswere equally tolerant to arsenatebut sensitivity to lead was greater in fish from Washington than in those from Alaska. Results of repeated tests with zinc and juveniles from Alaska were variable, and 96-hr LCsO’sdiffered by a factor of 2.2. Zinc was not tested with juvenile coho salmon from Washington. In rainbow trout, juveniles were significantly more sensitive than alevins to each inorganic tested (Table 3). As observed in Arctic grayling, differences in sensitivity between life stageswere smallest for copper (2.6-fold), intermediate for arsenate(>5.3fold) and zinc (12.8-fold), and largest for lead (> 17.6-fold). Interspecies

Comparisons

Arctic grayling juveniles from Alaska were consistently the most sensitive species and life stage to arsenate, copper, and zinc; except for zinc, differences in the 96-hr LCsO’swere significant (Table 4). Among the other fish, there was no consistent order of relative sensitivity to these inorganics. Arctic grayling from Montana were the least sensitive to copper but among the most sensitive to arsenate. Conversely, rainbow trout were among the most sensitive to copper but the least sensitive to arsenate. Among alevins, coho salmon were significantly more sensitive than rainbow trout to all three inorganics; among juveniles, rainbow trout were significantly more sensitive than coho salmon to zinc. One of the most significant findings wasthat juvenile Alaska grayling were at least 10 times more sensitive to each inorganic than were juvenile Alaska coho salmon; the ratio between 96-hr LCsO’swas about 11 for arsenate,copper, and zinc and >56 for lead. For a given life stage, interspecies differences in sensitivity to copper, zinc, and arsenatewere similar; the ratio of highestto lowest 96-hr LC50’sfor alevins and juveniles was 6.5 and 10.6 for copper, 4.0 and 10.7 for zinc, and >3.5 and 13.2 for arsenate. For each inorganic, the high to low ratio of 96-hr LCSO’swas the smallest for the alevins; however, if the 96-hr LCsO’sfor Arctic grayling juveniles from Alaska are omitted, the ratios for arsenate and copper are the smallest for the juveniles. For a

TABLE

3

ACUTE TOXICITY (LC&‘s IN pg liter-’ AND 95% CONFIDENCE INTERVALS IN PARENTHESES) OF COPPER, ZINC, ARSENATE, AND LEAD TO DIFFERENT LIFE STAGES OF COHO SALMON AND RAINBOW TROUT IN SOFT WATER AT 12°C Source

of

Life

stage Duration

Inorganic

fisha

and

year

class

of exposure

mean weight

24

96 Coho

Copper

AK 1985

WA 1987

0.47

g

42.2

(35.3-50.4)

23.9

(19.9-28.7)

g

62.3

(51.4-75.4)

31.9

(26.7-38.2)

alevin

AK 1985

Lead

21.0

(15.1-29.2)

57.0

(48.2-67.3)

19.3

(13.4-27.8)

23.4

(17.2-31.8)

15.1

(11.8-19.2)

100

0.41

g

(75.134)

0.47

g

2850

(2060.3940)

820

(610.1130)

0.63

g

5610

(4700.6690)

1810

(1340.2450)

0.94

g

5610

(4700.6690)

1650

(1050-2600)

3140

(1980.4970)

727

(507.1042)

71000

(xooo-100000)"

WA 1987

alevin

AK 1985

0.47

WA 1987

alevin

g

58500

698000

(547000.889000)

306000

(216000-433000)

g

88000

(74000-105000)

43600

(32500-58500)

AK 1985

0.94

g

>18000

WA 1987

alevin

>10000

alevin

>28000

21700

(18100-26000)

>17000

4180

(2920.5980)

g

>18000 7000

Rainbow copper

MT 1986

Zinc

MT 1986

alevin 0.60

g

alevin 0.60

MT 1986

g

alevin

MT 1986

g

alevin

= source:

AK = Alaska

(Clear

Salmon

Hatchery,

Hatchery.

Ennis,

Montana).

b No partial

kills;

concentration 100%

with

(39.4-54.6)

18.9

(15.7-22.8)

State

0% martality

(30.7-42.4)

13.8

(10.0-16.8) (1850-2550)

215

(157.295)

169

(118-243)

>360000

141000

(118000-170000)

67500

(56100-81200)

(12900-73400)

30000

(21600-36000)b

.c Hatchery,

upper

360000

1.04 Lead

(49400-69300)

0.41

0.41

AKSeIlate

salmon

0.87

alevin

Zinc

(hours)

or

limit

= lowest

limit

WA = Washington (Ennis

National

= highest test

Fish

test

concentration

with

mortality.

= No LC50

value

could

be calculated

because

inverted.

331

concentration-mortality

data

were

332

BUHL

AND

HAMILTON

TABLE 4 FISH SPECIES RANKED ACCORDING TO THEIR ACUTE SENSITIVITY (96-hr LCs,‘s IN PARENTHESES) TO COPPER, ZINC, AND ARSENATE (LEAD WAS NOT INCLUDED BECAUSE OF INSUFFICIENT DATA: SPECIES AND YEAR CLASS WITH THE SAME UNDERLINE ARE NOT SIGI\JIFICANTLY DIFFERENT) Inorganic (unit)

copper (pg

Life

stage

al e\.in

cos-1987

literml)

(LO.l)b

juvenile

Zinc (pg

Species

alevin

liter-l)

juvenile

Arsenate

alevin

RBT-1986

cos-1987

cos-1985

(2.6)b

(13.8)

(15.1)

(27.6)b

cos-1987

.ARG-1986

RET-1986

.ARG-1988

(I271

(1580)

(2170)

ARC-1985

AR&1986

ARC-1988

RBT-1986

(168)b

(169,

COS-1987

RBT-1986

(5

b Geometric

mean

of

96.hr

ARG-1986

ARC1985

ARG-1985

.ARG = Arctic

RET-1987

(67.4)

(102)

a Species:

classa

(16.0) -__

AH-1986

juvenile

year

(23.9)

(126)b

(mg liter-l)

.ARG-1986

and

lib

greyling:

(166) ARG-1988 (197)

ARG-1987 (131)

ARG-1986

ARG-1987

(30.0)

(49.1)

(2920) _-

(306)

cos-1985 (1348)b

(>360)

ARG-1988

cos-1987

.ARG-1986

cos-1985

RBT-1986

(31./)b

(43.6)

(47.1)

(58.5)

(61.5)

COS = coho

salmon:

RBT

rainbow

trout

LCso's,

given life stage. copper was the most toxic inorganic by zinc and arsenate.

to all fish stocks tested, followed

Tests with mixtures of arsenate, copper. lead, and zinc combined in ratios approximating those found in streams with placer mines indicated that copper was the primary toxic component in each mixture and that at these ratios the presence of arsenate, lead, and zinc did not significantly modify copper toxicity to salmonids (Table 5). In four tests. the 96-hr LC50 of copper in the mixtures was significantly different from the individual 96-hr LCso of copper according to the test of Sprague and Fogels ( 1977), but the 95% confidence intervals of the individual 96-hr value overlapped those for these mixtures (Table 5). The relative toxic contribution of copper to each mixture for a given species and life stage accounted for 297%) of the summed toxic units, except in tests with juvenile rainbow trout and mixtures I and II. In these tests with

TOXICITY

OF

INORGANICS

TO

TABLE

YOUNG

333

SALMONIDS

5

TOXICITY (pg liter-‘) OF COPPER (Cu) IN MIXTURES WITH ARSENATE (As), LEAD (Plb), AND ZINC‘ (Zn) COMBINI~D IN ENVIRONMENTALI.~ RELEVANT RATIOS TO EARLY LIFE STAGES OF ARCTIC GRAYLING, COHO SALMON, AND RAINBOW TROUT IN Son WATER AT 12°C

Acrm

96-hr LC,, Of cu Ratio to Cu

(95% confidence

intervals)

Toxic units

__Mixture

Rs

Pb

Zn

Species”

YeaI class

I

0.16

(I.21

0.96

AI6

1985

II

1.29

1.74

III

0.60

1.40

0.85

IV

0.60

0.109

0.44

v

2.00

0.55

1.01

VI

0.65

1.70

1.23

a Species:

?.FG= Arctic

’ The %-hr K,,

qraylinq;

Mixture

Individml

Cu

Rs

Pb

2”

sun

fri

5.8

(3.7-8.9)

9.6

16.9-13.3)

0.60

~0.01 CO.01

0.02

0.62

jwenile

2.3

(1.8-4.2)’

2.6

(1.7-3.9)’

1.12

~0.01

0.02

1.16

0.02

1986

alevin

19.8 [15.2-25.8)

23.9 (20.1-28.4)

0.83