Preindustrial and present-day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum (Alm), and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present-day inferences) and bottoms (pre-1850 inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present-day changes in lake water chemistry show that approximately 25–35% of the target population has acidified. The magnitude of acidification was greatest in the low-alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and receives the highest annual average rainfall in the region. We estimate that ~80% of the target population lakes with present-day measured pH [Formula: see text] and 30–45% of lakes with pH between 5.2 and 6.0 have undergone large declines in pH and ANC, and concomitant increases in [Alm]. Estimated changes in [DOC] were small and show no consistent pattern in the acidified lakes. This study provides the first statistically based regional evaluation of the extent of lake acidification in the Adirondacks.
PNL-7487 UC-603 encouragement and support, Robert Turner and Craig Brandt of Oak Ridge National Laboratory for assistance in data analysis, S. S. Dixit and B. F. Cumming of Queen's University for providing unpublished data; and E. C. Krug of the Illinois State Water Survey for his detailed critique of the report. This research would not have been possible without the considerable efforts of Robbins Church and coworkers in the Direct Delayed Response Project and of John Smol and coworkers in the PIRLA-11 project • iii Thirty-three lakes that had been statistically selected as part of the U.S. Environmental Protection Agency's Eastern Lake Survey and Direct Delayed Response Project (DDRP) were used to compare the MAGIC (watershed) and Diatom (paleolimnological) models. The study lakes represented a well-defined group of Adirondack lakes, each larger than 4 ha in area and having acidneutralizing capacity (ANC) < 400 ~eq L•'. The study first compared current and pre-industrial (before !850) pH and ANC estimates from Diatom and MAGIC as they were calibrated in the preceding Paleocological Investigation of Recent Lake Acidification (PIRLA) and DDRP studies, respectively. Initially, the comparison of hindcasts of pre-industrial chemistry was confounded by seasonal and methodological differences in lake chemistry data used in calibration of the models. Although certain differences proved to be of little significance for comparison, MAGIC did predict significantly higher pre-industrial ANC and pH values than did Diatom, using calibrations in the preceding studies. To remove known calibration biases, both models were recalibrated for selected scenarios. The more realistic pre-industrial sulfur deposition level (~13% of 1984 value) in the recalibrated MAGIC scenario reduced the hindcast ANC values significantly, reducing the discrepancy between the two models and indicating the sensitivity of process-level watershed models to assumptions concerning the quantity of atmospheric deposition. The reaggregation to subregional soils data appeared to produce little effect on hindcast ANC and pH values. A recalibrated MAGIC scenario using reaggregated soils data, sulfate loss-tolake sediment, and partial pressure of C0 2 specific to the Adirondack subregion, was also compared to a Diatom scenario using a similar sum of base cations minus sum of strong acid anions definition of ANC. The result yielded MAGIC hindcasts closer to Diatom hindcasts, but still significantly higher pre-industrial ANC and pH values than suggested by the Diatom model. Both models suggest acidification of low ANC Adirondack region lakes since preindustrial times, but differ primarily in that MAGIC inferred greater acidification and that acidification has occurred in all lakes in the comparison, whereas Diatom inferred that acidification has been restricted to low ANC lakes (
Ein sehr empfindliches Reagenspapier auf freies Ammoniak wird nach A. S e l l e sen.*) folgendermaassen erhalten: Wenn man circa 10 Stilck Bliithen der sehr dunkelblauen Hyacinthe KSnig Wilhelm yon dem unteren, den Fruchtknoten umschliessenden Theil befreit, trocknet, zu feinem Pulver reibt und dann mit 20 CC. 90 proc. Weingeist digerirt, erh~lt man eine ges~ttigte amethytstfarbene Tinktur, mit welcher man circa einen haiben Bogen schwedischen Fliesspapiers trankt. Das nach dem Trocknen schSn blau gefarbte Papier ist schon im trocknen Zustande, noch mehr aber angefeuehtet ungemein empfindlich gegen Ammoniakgas, indem seine blaue Farbe davon in ein schSnes Griin t~bergeftihrt wird. Der nach der Extraction mit Weingeist verbleibende Rtiekstand wird beim Abtrocknen wieder blau und gibt durch eine zweite Digestion mit Weingeist nochmals eine Tinktur, mit welcher man abermals Papier fiirben kann. Ueber die Reinigung tier Oxals~ure dutch Sublimation. Fr. S t o l b a**) hi~lt ftir die beste Methode zur Reinigung yon Oxalsi~ure zu analytischen Zwecken die Sublimation derselbcn und verfi~hrt bei deren Ausftihrung in der Weise, dass er sie erst in einer flachen Porcellausehale unter zeitweiligem Umriihren au einem warmen Orte so lange stehen l~sst, bis sie ihr Krystallwasser m(iglichst vollsti~ndig verloren hat, d. h. bis eine kleine Probe in einem trockenen Probirgliischen vorsichtig und allmi~hlich erhitzt ohne viel WassertrSpfchen abzugeben sublimirt. Hierauf wird die Si~ure etwa 1/2 bis a]4 Zoll hoch in ein flaches Beeherglas eingetragen und letzteres in eine eiserne, mit Eisenfeilspi~hnen geftillte Schale so eingesetzt, dass die Eisenfeilsp~hne aussen eben so hoch stehen wie die Oxals~ture im Jnneren. Das Becherglas wird oben mit einem Kegel yon reinem Filtrirpapier tiberbunden. Die Schale wird nun mit der Gasflamme erhitzt, wobei jedoch darauf zu achten ist, dass die Temperatur nicht zu rasch steige, weil zu starkes Erhitzen im Anfange Zersetzung der S~ure und durch Spritzen Verunreinigung des Sublimates zur Folge hat. Zuni~chst trocknet hierbei die Oxalsaure noch vollst~ndig aus und sublimirt dann. Das Sublimat erscheint in zwei verschiedenen Schichten, einer oberen, blendend weissen, lockeren, welche sieh leicht abnehmen l~tsst, und einer unteren, sti~rkeren~ fester zusammenh~ngenden und gelblichen. Man 10st *) Pharm. Centralhalle 9. p. 168. **) Polyt. l~lotizbl. Bd. 23. p. 332.
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