De Schamphelaere, Karel

Heijerick, Dagobert G

Janssen, Colin

Ghent University Academic Bibliography

Addendum to Report ZEH-WA-01   Development and validation of biotic ligand models for predicting chronic zinc toxicity to fish, daphnids and algae.   De Schamphelaere K and Janssen C Ghent University, January 19th 2004   Following additional experiments have been conducted since the final report of ZEH-WA-01 (28th February, 2003) was released:  • Chronic (30d) rainbow trout toxicity tests at Ca concentrations of 0.2, 1 and 4 mM • A chronic (30d) rainbow trout toxicity test using an additional natural water (Brisy) • Chronic (21d) toxicity tests with Daphnia magna in 6 natural waters and in one synthetic water (reference test)  The results of these experiments are described in the following three sections.   1. Additional Ca-tests with rainbow trout and refinement of chronic Zn-BLM   The additional Ca-tests allowed deriving final chronic BLM-constants. This must be considered an important improvement as in the ZEH-WA-01 report some assumptions were taken to derive the Ca-competition constant, resulting in a range of possible log K’s instead of one log K (see Table 3.18 in ZEH-WA-01). In this “addendum”-report we will only focus on the refinement of the chronic Zn-BLM for fish and not on the acute Zn-BLM (which we also described in ZEH-WA-01, but which is of less relevance for the risk assessment).   It is noted that the Table numbers below are not starting from 1. They are given the numbers of corresponding Tables in ZEH-WA-01 and they can be considered as extensions of the latter ones. The raw data are given in the annexes.  Table 3.6 Average physico-chemistry of the test-media used for the BLM-development Code pH Hardnessa (mg CaCO3/L) Ca (mg/L) Mg (mg/L) Na (mg/L) K (mg/L) SO4 (mg/L) Cl (mg/L) Alkalinity (mg CaCO3/L) CA-0.2 7.61 29.1 9.14 1.53 18.3 2.11 11.1 16.2 47.1 CA-1 7.58 102 38.2 1.65 17 1.92 11.7 69.2 52.4 CA-2 * 7.87 190 73.9 1.38 15.7 1.51 12.3 144 66.8 CA-4 7.68 396 156 1.68 17.1 1.99 11.1 270 44.1 a Hardness is calculated from measured Ca and Mg levels * test already performed in ZEH-WA-01         Table 3.7 Effect concentrations of Zn (µg/L) used for the BLM-development. Numbers between brackets indicate 95% confidence limits Code 96h-LC50 30d-LC50 30d-LC10 30d-NOEC CA-0.2   194   (152 -   248) 159 (110-228) 34.5 (14.5-82.4) 78.9 CA-1   904   (608 - 1343) 759 (568-1014) 171 (91-324) 169 CA-2 * 1470 (910-2300) 1240 (760-2040) 290 (96-880) 885 CA-4 2280 (1460 - 3560) 1860 (1230-2820) 337 (113-1010) 786 * test already performed for ZEH-WA-01   As anticipated in ZEH-WA-01, we have now indeed observed a clear decrease of chronic Zn-toxicity with increased Ca-concentrations, i.e. about a factor of 10 with an increase from 0.2 to 4 mM Ca. The 30d-LC50 data have been used to calculate speciation and to estimate the BLM constants for chronic toxicity (Tables 3.8, 3.13 and 3.15).   Table 3.8 Chemical speciation in the chronic toxicity tests used for the BLM-development. Ca2+, Mg2+, Na+ and H+ are given as chemical activity (in M); 30d-LC50 is given as Zn2+-activity (in M) Code Ca2+ Mg2+ Na+ H+ 30d-LC50 CA-0.2 1.65E-04 4.57E-05 7.58E-04 2.45E-08 1.54E-06 CA-1 6.55E-04 4.66E-05 6.90E-04 2.63E-08 7.22E-06 CA-2* 1.19E-03 3.68E-05 6.25E-04 1.35E-08 1.03E-05 CA-4 2.33E-03 4.13E-05 6.62E-04 2.09E-08 1.56E-05 * test already performed in ZEH-WA-01   Table 3.13 Slopes (S) and intercepts (I) of regression equations for Ca for chronic toxicity; r2 is the correlation coefficient for the regression; R is the ratio slope/intercept.   S I (M) r2 RCa (M-1) Log RCa Data points used: CA-0.2, CA-1, CA-2 and CA-4 Chronic 6.16E-03 1.97E-06 0.95 3.12E+03 3.5   Tabel 3.15 Stability constants (K, in M-1) for the competing cations for the chronic BLM (30-day mortality) calculated with Eq. 8. Data used to calculate the constants are given for each cation investigated: the R-value (in M-1 ; see Tables 3.9, 3.10, 3.11 and 3.13) and the mean activity of the other competing cations (in M) in the tests used to derive the R-values (see Table 3.8). CationX  RX (Ca2+)X (Mg2+)X (Na+)X (H+)X KXBL Log KXBL Ca2+ 3.12E+03 NA 4.26E-05 6.84E-04 2.13E-08 3.99E+03 3.6 Mg2+ * 7.12E+02 1.49E-04 NA 7.27E-04 1.98E-08 1.29E+03 3.1 Na+ * 1.47E+02 1.55E-04 5.01E-05 NA 3.39E-08 2.60E+02 2.4 H+ * 7.36E+05 1.48E-04 4.48E-05 4.25E-03 NA 2.11E+06 6.3 NA = not applicable * test already performed in ZEH-WA-01   The constants of the refined chronic rainbow trout Zn-BLM are given in Table 3.18. Table 3.18 demonstrates that the competition constants are well within the 90% confidence interval estimated in ZEH-WA-01. Figure 3.1 and Table 3.19 give the predictive capacity of the BLM for the different synthetic test media. All LC10s and LC50s are predicted within < factor of 2.    Table 3.18 Old (ZEH-WA-01 report, given as 90% confidence interval) and new (present report) BLM-constants for chronic zinc toxicity to juvenile rainbow trout   Old New Log KZnBLa 5.31 5.5 Log KCaBL 3.35 – 4.01 3.6 Log KMgBL 3.04 – 3.31 3.1 Log KNaBL 2.33 -2.61 2.4 Log KHBL 6.24 – 6.52 6.3 50%ZnBLf   0.189 -104 0.246±0.070 10%ZnBLf   0.067 - 0.034 0.0938±0.038 a Log KZnBL was originally set to the same value as reported in Heijerick et al. (2002) for the acute Zn-BLM for D. Magna, but the new model has the same value as the one reported by Santore et al. (2002) for the acute Zn-BLM for fish   1010010001000010.0 100.0 1000.0 10000.0observed ECx (µg Zn/L)predicted ECx (µg Zn/L)30d-LC5030d-LC10 Figure 3.1 Observed and predicted 30d-LC50s and 30d-LC10s for test media used for the development of the chronic BLM.  Tabel 3.19 Observed and predicted 30d-LC50s and 30d-LC10s of Zn (µg/L). Numbers between brackets indicate 95% confidence limits. Code Observed 30d-LC50 Predicted 30d-LC50 Observed 30d-LC10 Predicted 30d-LC10 RF-B 177 (132-238) 194 38.4 (19.7-74.5) 62 RF-CA4 >1530 NC NC NC RF-MG3 583 (504-676) 482 NC NC RF-NA5 282 (196-450) 302 83.2 (24.9-278.1) 96 MG-B 108 (81-143) 195 46.1 (25.5-83.6) 62 MG-0.2 151 (121-189) 211 67.9 (33.4-138.0) 67 MG-1 212 (183-247) 319 103 (77-139) 101 MG-2 224 (185-247) 403 104 (70-156) 128 MG-3 339 (269-428) 501 99.1 (58.7-167.5) 159 PH-5.5 802 (630-1023) 676 312 (184-531) 214 PH-6.5 368 (214-632) 315 99.1 (30.3-324.3) 100 PH-7.5 361 (226-579) 306 73.6 (23.4-231.7) 97 CA-B* 159 (110-228) 198 34.5 (14.5-82.4) 63 CA-1 759 (568-1014) 416 171 (91-324) 132 CA-2* 1240 (760-2040) 736 290 (96-880) 233 CA-4* 1860 (1230-2820) 1291 337 (113-1010) 409 NC = not calculated as no EC10 could be derived for these tests * new experiments   2. Test with rainbow trout in an additional natural water: validation of the refined BLM using surface waters  An additional test with a spiked natural surface water was conducted. To that end, as in ZEH-WA-01, a surface water (Brisy), was concentrated in the field using reverse osmosis. In the laboratory, the surface water was re-diluted and Ca and Mg concentrations were adjusted to those measured in the original surface water. The physico-chemistry and the ecotoxicity test results for this test water and for the other natural waters are given in Tables 3.21 to 3.22.   Table 3.21 Average physico-chemistry during the toxicity tests in reconstituted natural waters used for the rainbow trout BLM-validation.  Code pH DOC (mg/L) Hardness a (mg CaCO3/L) Ca (mg/L) Mg (mg/L) Na (mg/L) K (mg/L) SO4 (mg/L) Cl (mg/L) Alkalinity (mg CaCO3/L) ANK* 7.76 22.9 104 32.0 5.77 34.2 0.74 56.3 93.4 49.1 MAR* 8.13 6.22 176 49.0 13.1 100 0.89 153 158 68.5 VOY* 6.80 3.92 28.2 9.54 1.06 16.7 0.87 14.1 22.8 17.1 BIH* 6.15 4.25 23.3 7.09 1.38 5.59 0.26 7.84 10.83 1.7 BRISY 7.08 2.84 31.5 8.05 2.77 5.9 0.48 13.5 10.4 14.3 a Hardness is calculated from measured Ca and Mg levels (mg CaCO3/L) * tests described in ZEH-WA-01   Table 3.22 Effect concentrations of Zn (µg/L) in the natural waters. Numbers between brackets indicate 95% confidence limits. Code 30d-LC50 30d-LC10 30d-NOEC ANK* 1970 (1460-2670) 902 (483-1683) 771 MAR* 1850 (1410-2410) 578 (322-1038) 696 VOY* 406 (263-624) 185 (99-346) 324 BIH* 582 (394-859) 259 (123-548) 370 BRISY 337 (292-389) 219 (111-432) 199 * tests described in ZEH-WA-01   Tables 3.23 and Figure 3.2 present the predictive capacity of the refined chronic Zn-BLM.   Table 3.23 Observed and predicted 30d-LC50s and 30d-LC10s of Zn (µg/L). Numbers between brackets indicate 95% confidence limits. Predictions were carried out with and without DOC assumed. Code Observed 30d-LC50 Predicted 30d-LC50  Predicted 30d-LC50 (no DOC) Observed 30d-LC10 Predicted 30d-LC10  Predicted 30d-LC10 (no DOC) ANK 1970 (1460-2670) 2014 434 902 (483-1683) 1147 141 MAR 1850 (1410-2410) 1284 800 578 (322-1038) 587 258 VOY 406 (263-624) 404 211 185 (99-346) 159 68 BIH 582 (394-859) 473 265 259 (123-548) 169 84 BRISY 337 (292-389) 328 184 219 (111-432) 134 60      1010010001000010 100 1000 10000observed ECx (µg Zn/L)predicted ECx (µg Zn/L)30d-LC5030d-LC10 Figure 3.2 Observed and predicted 30d-LC50s and 30d-LC10s for natrual waters.    The results in Table 3.23 and Figure 3.2 Clearly demonstrate that all LC50s and LC10s are predicted with an error of less than factor 2. Comparing the predictions with DOC and those without DOC, it is observed that DOC accounts for a factor of 2 to 8 decrease of toxicity (when LC10s are considered). Hence, DOC must be considered a significant parameter in evaluating the risks of zinc in natural waters.   3. Chronic Zn toxicity to Daphnia magna in natural waters  Six natural surface waters were sampled. Tests were conducted with these non-manipulated samples and not with reconstituted samples as for the fish tests (i.e. reverse osmosis concentration followed by dilution in laboratory). An additional test was conducted in synthetic test water with increased Ca (2 mM) and Mg (0.5 mM). The physico-chemistry of these waters is summarized in the Table 4.12. Since validation tests were not reported in ZEH-WA-01, the table numbers below start from 4.12 (Table 4.11 was the last Table in the chapter on the Daphnia model in ZEH-WA-01). Table 4.12 gives the physico-chemistry of the natural waters.  Table 4.12 Physico-chemistry of synthetic and natural waters used for the BLM-validation.  Water pH DOC (mg/L) Hardness a (mg CaCO3/L) Ca (mg/L) Mg (mg/L) Na (mg/L) K (mg/L) SO4 (mg/L) Cl (mg/L) Alkalinityb (mg CaCO3/L) Synthetic 7.15 0.3 b 250 80.2 12.2 17.7 3.0 48.0 73.8 33.2 Ankeveen 6.77 17.3 123 38.3 6.5 17.4 6.1 127 50.0 12.3 Brisy 7.34 2.53 26.4 5.0 3.4 8.8 2.1 9.5 23.0 13.6 Markermeer 8.03 7.49 189 52.7 14.0 87.3 8.7 109.0 318 127 Regge 8.00 9.87 183 60.1 8.0 52.9 10.4 63.0 144 165 Rhine 8.22 2.30 196 61.0 10.7 55.4 5.0 57.0 215 159 Voyon 8.40 4.17 122 37.1 7.1 10.0 1.3 20.0 21 125 a Hardness is calculated from measured Ca and Mg levels (mg CaCO3/L) b background DOC concentration of deionized water in our laboratory (~300µg/L)   Table 4.13 gives the observed and predicted 21d-EC50s and 21-day NOECs obtained in these tests. Figure 4.2 visualizes the observed versus predicted EC50s and NOECs.   Table 4.13 Observed and predicted 21d-EC50 and 21d-NOEC of Zn to Daphnia magna (in µg Zn/L).  Water Observed EC50 Predicted EC50 Observed NOEC Predicted NOEC Synthetic 299 237 155 165 Ankeveen 536 569 491 428 Brisy 112 177 94.5 136 Markermeer 313 679 244 540 Regge 473 824 251 664 Rhine 242 497 143 370 Voyon 171 450 72.7 354    1010010001000010 100 1000 10000observed ECx (µg Zn/L)predicted ECx (µg Zn/L)chronic 21d EC50chronic 21d NOEC Figure 4.2 Observed and predicted EC50 and NOEC of Zn for Daphnia magna in natural surface waters.   Tables 4.13 and Figure 4.2 indicate that 3 of the 6 EC50s, and 2 of the 6 NOECs are predicted within a factor 2. The EC50 and NOEC in synthetic water (increased hardness) were predicted within a factor 2 of the observed values. The reason for this underestimation of toxicity, especially at the NOEC-level, needs further investigation.ANNEXES   Table 3B.4 Results of the additional Ca-tests (2nd test series) with rainbow trout. * =significantly different from control; dissolved Zn concentrations in bold are NOECs CODE Dissolved Zn (±SE) (µg/L) 96hours mortality (%) 30days mortality (%) p (dunnet) 30d-mortality r3 (±SE) (d-1) p t-test (r3) CA-0.2 <5.0 0 0  0.0434 (±0.0020)  32.7 (±0.4) 8.3 16.7 0.305 0.0430 (±0.0056) 0.978 78.9 (±0.6) 25.0 25.0 0.124 0.0284 (±0.0073) 0.412 166 (±4) 41.7 50.0 0.004* 0.0195 (±0.0177) 0.210 346 (±8) 72.7 72.7 <0.001* 0.0161 (±0.0011) 0.006* 773 (±18) 83.3 100.0 <0.001*   CA-1 <5.0 0 0  0.0391 (±0.0044)   77 (±2) 0.0 0.0 0.808 0.0321 (±0.0063) 0.601 170 (±3) 10.0 10.0 0.313 0.0305 (±0.0048) 0.448 363 (±9) 26.7 26.7 0.009 0.0301 (±0.0069) 0.536 848 (±36) 46.7 53.3 <0.001* 0.0418 (±0.0068) 0.844 CA-4 <5.0 6.7 6.7  0.0357 (±0.0047)  346 (±8) 10.0 10.0 0.713 0.0467 (±0.0069) 0.551 786 (±10) 0.0 20.0 0.231 0.0327 (±0.0076) 0.884 1670 (±10) 58.3 58.3 <0.001* 0.0498 (±0.0049) 0.410 3580 (±260) 50.0 50.0 <0.001* 0.0395 (±0.0043) 0.787 7323 100.0 100.0 <0.001*   Table 3B.5 Results of the test in the 5th natural water (Brisy) with rainbow trout. * =significantly different from control; dissolved Zn concentrations in bold are NOECs CODE Dissolved Zn (±SE) (µg/L) 96hours mortality (%) 30days mortality (%) p (dunnet) 30d-mortality r3 (±SE) (d-1) p t-test (r3) Brisy <5.0 0 0  In progress  37.5 (±12.2) 0 0 0.787 In progress  199 (±12) 6.7 6.7 0.636 In progress  346 (±15) 48.3 55.2 0.005* In progress  927 (±36) 87.5 100 <0.001* In progress    

Development and validation of biotic ligand models for predicting chronic zinc toxicity to fish, daphnids and algae

https://biblio.ugent.be/publication/8636182/file/8636183

Development and validation of biotic ligand models for predicting chronic zinc toxicity to fish, daphnids and algae

Abstract

Similar works

Full text

Available Versions

Ghent University Academic Bibliography