Long Term Precipitation Chemistry Monitoring on Vancouver Island by Warren McCormick, P.Eng. Ministry of Water, Land and Air Protection Job title is Air Quality Meteorologist at the Regional Office in Nanaimo for Vancouver Island Region

Objectives of Presentation Intended to present an overview of the monitoring program in terms of spatial and temporal ranges and general results Not intended to be a scientific dissertation on aqueous precipitation chemistry Share with the wider scientific community

Some History Province wide monitoring started in mid 1980’s due to general “Acid Rain” concern (mostly in east) Since Ministry funding was by region most have slowly discontinued rain monitoring in favour of permittee impact monitoring Deemed important in VIR due to some soil sensitivity and river flow patterns Precipitation chemistry was done in most regions of the province until the early 1990’s. Most other regions found that there was little impact and there was less soil and river sensitivity to acid rain. Vancouver Island has some areas of moderate to high soil sensitivity to acid rain and river flow patterns on the coast are rain-driven; there is relatively little snow pack and large lakes therefore, highest flows occur in winter, lowest in summer.

Locations Port Hardy – long time station, started in mid 1980’s, samples collected at airport Campbell River – relatively new, started in mid 1990’s, samples colleted at the airport Nanaimo – long time station started in mid 1980’s moved in mid 90’s, compilation of 2 sites: Nanoose and Nanaimo Regionall Office Victoria – long time station (NAPS), started in mid 1980’s moved in late 90’s, compilation of 2 sites: Quadra&Yates and Topaz Other short, historical datasets were operated by the Province at sites near Victoria: Spectacle Lk, Pender Is. and Saturna Is. Federal Gov’t continues to do rain sampling at the Saturna Is. site under CAPMoN program.

Equipment Wet/Dry sampler, sensor activated lid to expose sample collection bottle inside bucket. Sample is covered during times of no rain to stop evaporation and exclude dust from sample. Samples represent a week average sample, usually collected on a Tuesday. Analysis is conducted following the LRTAP protocol.

Overview of Results Annual pH trends Annual SO4 Concentration and Deposition trends Annual NO3 Concentration and Deposition trends

pH Graphs show: filled box is precipitation-weighted annual mean pH, white box shows +/- 1 Standard Deviation of pH measurements and vertical lines show minimum and maximum pH measured that year. Period average is 5.45, close to the expected rain pH of 5.5 to 5.6, very few events with a pH below 4.0, pH average over last 5 years is 5.43 Results indicate a site unaffected by anthopogenic emissions

pH Period average is 4.85, but no extreme events less than 4.0 Possibly shows a site affected by anthropogenic emissions but far from source region

pH Period average pH is 4.86 but recent average (last 5 years) pH is 4.76 There are historical and recent events with pH lower than 4.0

pH Shows improvement over the period, with a period average pH of 4.81 but a recent average pH of 4.93. Now has 2nd best average pH values compared to Port Hardy. There have been no events with a pH under 4.0 since early 90’s.

Sulphate Graphs show Excess Sulphate only, concentrations have been corrected for contribution from sea salt sources. Hatched bar shows annual precipitation amount, blue bar is annual concentration value, green line is annual deposition value At this site large amounts of precipitation produces a high deposition value in spite of low concentration amounts. Period average Concentration is 0.26 mg/l and period average Deposition 3.58 kg/ha Last 5 year recent Concentration has been 0.18 mg/l and last 4 year recent Deposition has been 2.52 Kg/ha Although there appears to be a slight decrease in Sulphate levels at this site in recent years, there is no correlation with the pH values in recent years.

Sulphate Period average Sulphate Concentration is 0.51 mg/l and period average Deposition is 2.69 kg/ha Although Sulphate Concentrations are higher than at Port Hardy the lower annual precipitation amounts produce a lower Deposition value.

Sulphate Period average Sulphate Concentration is 0.78 ug/l and period average Deposition is 4.09 kg/ha However, last 5 year recent average Concentration is 0.96 ug/l and Deposition is now 5.06 kg/ha Break in record starting in 1995 was time period when the Nanoose station was closed, continuing at the Nanaimo office in 1998.

Sulphate Period shows an obvious downward trend. Period average Sulphate Concentration is 1.21 ug/l and Deposition is 4.82 kg/ha. However, last 5 year recent average Concentration is now only 0.61 ug/l and Deposition is now only 1.77 kg/ha

Nitrate No correction, full NO3 analysis Period Average Concentration is 0.20 ug/l, and average Deposition is 2.84 kg/ha, recent average (last 5 years) Concentration is 0.20 ug/l and Deposition is 3.00 kg/ha Deposition is highly correlated with the rainfall amounts.

Nitrate Period average Concentration is 0.87 ug/l and Deposition is 4.76 kg/ha

Nitrate Period average Concentration is 0.77 ug/l and Deposition is 4.00 kg/ha, but recent average (last 5 years) Concentration is 1.05 ug/l and Deposition is now 5.46 kg/ha

Nitrate Data shows a downward trend but not as significant as with the Sulphate data. Period Average Concentration is 0.67 ug/l and Deposition is 2.64 kg/ha but recent average (last 5 years) Concentration is only 0.46 ug/l and Deposition is 1.28 kg/ha

Summary Port Hardy – good rain quality, somewhat high deposition with respect to concentrations but is due to high rainfall, no trend Campbell R. – slightly depressed pH, higher concentrations but also higher depositions with less rain, no trend (short period)

Summary (con’t) Nanaimo – long term pH similar to CR, but recent pH is lower, recent concentrations and deposition now highest of all sites, trend is up Victoria – recent pH has improved, significant decrease in deposition, trend down but perhaps has leveled off Historical pattern was a gradient down island (best quality in north, worst in south), but recent pattern has changed.

Contact Info Warren McCormick Air Quality Meteorologist 2080-A Labieux Rd. Nanaimo, BC V9T 6J9 250 751-3171 warren.mccormick@gems9.gov.bc.ca