Report For the first 10 years of the project (1983-1993)

Abstract:

Between 1983 and 1985, the Acid Rain Monitoring (ARM) Project used as many as 1000 citizen volunteers to collect and help analyze more than 40,000 samples from 2444 lakes and 1670 streams, respectively 87% and 69% of the named lakes and streams in the state, and monitored a representative 453 randomly selected and 119 special interest lakes and streams for eight successive years (1985-1993) with approximately 300 volunteers. This report details the organizational effort that permitted maintenance of this ten year effort, the quality control efforts needed to insure that resulting data met scientific standards for quality, and the findings of ten years of extensive monitoring.

Results for the nearly comprehensive initial phases of the project show that 5.5% of lakes and streams in Massachusetts are acidified (pH < 5.0 and ANC < 0 µeq/l); 57.4% were sufficiently low in acid neutralizing capacity to be considered threatened by acid deposition (0<ANC<200 µeq/l); and 37.1% were not threatened (ANC > 200 µeq/l). Spring samples contained an average of 45% more H+ (pH 6.44 vs 6.60) and 32% less ANC (257 vs 376 µeq/l) than fall samples. Lakes were slightly more sensitive than streams. Geographically, higher ANC was typical of extreme western parts of the state and lower ANC was typical of the north-central and southeastern portions.

While results are more representative of Massachusetts lakes than the Eastern Lakes Survey because of planned exclusions in the latter's site selections, the differences are relatively small. Comparisons between ARM results and those from other areas and countries suggest that Massachusetts surface waters are comparable to those from other areas of the world that are very sensitive to acid deposition.

Most of the differences in water chemistry can be related to the underlying geology. The western edge of the state is substantially higher in most cations and anions than average while southeastern, north-central and the Berkshire Mountain region are lower. In three of six regions, sulfate levels were twice as high as anticipated from deposition and evapotranspiration. Massachusetts lake and stream sulfate levels were comparable to eastern Canada and other high deposition sites. Streams were higher than lakes in calcium, magnesium, potassium, sulfate, aluminum and silicon dioxide and lower in sodium, chloride, organic acids, iron, and manganese. The combination of relatively high organic acids and base cations may account for the somewhat smaller percentage of acidified surface waters than in other high deposition areas.

The coastal region has a higher proportion of sodium and chloride resulting from sea salt influences. Statewide, sodium and chloride levels exceeded the amount expected solely from sea salt. A substudy of 162 randomly selected streams suggested that only 4% of the salt concentration of these streams could be attributed to sea salt. The remainder was highly correlated with the number of road lane miles in each stream's watershed. Approximately 63% of the variance in stream sodium concentration were explained by the number of lane miles. Class 1 and 2 (interstate highways and major state roads) made the highest contribution with urban streets next. Rural roads contributed relatively little.

Analyses of long-term trends in pH, ANC and selected ions from 10 years of data on 330 streams and 181 lakes showed a significant but small increase in average pH and increase in ANC. For streams, the median slope after correction for hydrologic variation was +0.021 pH/yr and, for ANC, it was +2.4 µeq/l/yr. For lakes, the median slope (hydrologically corrected) was +0.016 pH/yr and +1.9 µeq/l/yr for ANC. Streams with higher ANCs show a faster rate of recovery than low ANC streams (4.15 µeq/L/yr vs 1.33 µeq/L/yr).

For pH, high ANC streams showed a more gradual increase than low ANC streams (0.018 H units/yr vs. 0.026 H units/yr. Sulfate declined by 1.8 and 1.4 µeq/L/yr for streams and lakes, respectively. There was no trend for base cations in streams but a significant trend for base cations in lakes (+1.5 µeq/L/yr). The latter was counteracted by an increase in chloride of 1.4 µeq/L/yr.

Most lakes and streams exhibited no significant trend for the 10 years of the study. However, 70 of 330 streams showed statistically significant increases in ANC, 11 showed decreases, 43 of 181 lakes increased in ANC while 7 decreased. Most of the streams and all of the lakes exhibiting statistically significant declines occurred in the southeastern portion of the state. In this group of lakes and streams only two lakes and two streams became acidic (dropped below 0.0 ANC and H 5.0) during the ten years of the study.

The thousand or more volunteers participating in the project were profiled through a questionnaire distributed in 1989. Of the 40% responding, roughly 50% were original participants, 69% were male, 79% were married, 70% had a college degree, 63% lived in small towns, 54% were native to Massachusetts, and 75% had household incomes between $20,000 and $75,000. In total, they listed 76 hobbies, sports and interests. They also listed membership in 69 civic organizations and 20 different religions or religious beliefs. Ninety-seven percent considered their efforts on the project to be worthwhile.

Acid Rain Monitoring Project . Blaisdell House . University of Massachusetts . Amherst, MA 01003
Françoise Walk, Statewide Coordinator . Phone: 413-545-5531. Fax: 413-545-2304