1) NEON measures alkalinity and acid neutralizing capacity (ANC) 26 times per year at each stream site to assess water's buffering ability. ANC includes particulates while alkalinity does not. Differences between the two measurements are usually small. 2) Analysis found that reducing ANC sampling to once monthly would still capture seasonality and meaningful differences, except at one site where larger differences require maintaining the full sampling frequency. 3) NEON also measures physical reaeration rates through experiments 10 times annually but could reduce to 6 and still maintain data quality by implementing process checks and targeting times of lower representation.

1. This material is based upon work supported by NSF’s National Ecological Observatory Network which is a major facility fully funded by the National Science Foundation
Christine Laney, Caren Scott, Kaelin Cawley
LTER ASM 2018, Pacific Grove, CA
October 2, 2018
NEON Optimization Examples
1

2. 1: Alkalinity & Acid Neutralizing Capacity (ANC)
• Goal: Reduce budget, without major decrease in quality of our data products
• Alkalinity and Acid Neutralizing Capacity (ANC) are measures of the water’s ability to buffer
systems from changes in pH
▪ ALKALINITY: filtered water
▪ ANC: non-filtered (whole) water
• At each stream site, NEON measures both alkalinity and ANC 26 times per year
▪ 12 monthly
▪ 14 based on hydrology
• If particulates do not add to buffering capacity, ANC will be equal to ALK
• Can we reduce the sampling of ANC?
Contact: Caren Scott (cscott@battelleecology.org)
2

3. How similar are ALK/ANC? Site ID
Mean Alk
meq/L
Mean
%Diff
ARIK 5.31 3
BIGC 0.60 5
BLDE 0.88 6
BLUE 6.20 3
CARI 0.60 5
COMO 0.19 10
CUPE 2.75 3
GUIL 1.69 5
HOPB 0.12 30
KING 6.24 3
LECO 0.09 14
LEWI 5.43 4
MART 0.30 10
MAYF 0.04 38
MCDI 5.60 5
MCRA 0.21 10
OKSR 0.56 7
POSE 0.86 5
PRIN 4.98 3
REDB 4.62 3
SYCA 5.26 4
WALK 2.05 3
WLOU 1.25 12
3

4. How similar are ALK/ANC?
• Significant differences at 7 sites
• But the differences are so small,
are they ecologically meaningful differences?
• USGS defines appropriate reproducibility of replicates
▪ good indication of ecologically meaningful differences
• ONLY 1 site had differences greater than USGS threshold
▪ LECO
ALK
meq/L
USGS
cutoff
>4 5%
>0.02 &
<4 10%
<0.02 1 meq/L
Commissioning
Tests
4

5. Is there a pattern to the differences?
• Even if overall the differences are small, is there a pattern?
• For example: Are differences are always greater in the spring?
▪ If they are, we can keep sampling both ALK and ANC in the spring
• Modelled the differences
▪ Total Suspended Solids—indication of particulates
▪ Specific Conductance—indication of hydrology
▪ Month—indication of hydrology
▪ Year
5

6. Is there a pattern to the differences?
There are some significant predictors of the difference, mostly by month
6

7. Recommendations:
• Very little difference between measurements of ALK and ANC
• Even when significant, the magnitude of the difference is smaller than what we
would find appropriate for replicate samples
• Of these small differences, some sites show that the differences are greater in
certain months
• We recommend reducing the ANC sampling
• Keep it at once a month to capture seasonality
• EXCEPT: LECO, significant difference that was greater than replicates should be
7

8. 2. Reaeration Optimization
8
Contact: Kaelin Cawley (kcawley@battelleecology.org)
Question
• Does collecting 6 reaeration experiments per year rather than 10 impact data
quality negatively?
• Physical reaeration is an important
component of enabling metabolism modeling
in aquatic systems
• Parts of an experiment:
1. Discharge measurement
2. Field measurements
3. Conductivity logger measurements
4. Tracer samples

9. Data Completeness
9

10. Future Process Quality Checks
▪ Quarterly QAQC checks from HQ and service now ticket(s) and tasks for incomplete experiments
▪ Attempt to reschedule reaeration experiments if one or more components are not completed, e.g.,
HOBO files or discharge data missing or corrupt
▪ Follow-up with the external labs to ensure data is returned in a timely manner
10
Future Data Quality Checks
▪ Develop relationships between physical reaeration
rates and stream discharge where possible using
the existing reaeration R package
▪ Target times of year when discharge is likely to be in
a range that isn’t well covered with existing
reaeration data
k600
versus Q

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