Table 1
Selected Administration de La Gestion de l’Eau (AGE) data collection parameters (Pickar 2021; AGE 2015).
| PHYSICAL AND CHEMICAL | BIOLOGICAL | HYDRO-MORPHOLOGICAL | NATURALLY OCCURRING SUBSTANCES ASSOCIATED WITH POLLUTION | OTHER POLLUTANTS | |
|---|---|---|---|---|---|
| Description | Temperature, parameters concerning oxygen, turbidity, pH | Indicators concerning aquatic plants, other organisms. | Indicators concerning water flow, depth, width of riverbed and river bank | Salinity, nutrients*, chlorophyll, metals | Pesticides, pharmaceuticals, other chemicals |
| Sampling frequency in major rivers | Monthly | Monthly/bimonthly | Continuously | Monthly | Monthly/after screening |
| Sampling frequency in other water bodies | Monthly/quarterly | Every 3 years | N/A | Monthly/quarterly | Irregularly |
[i] * Total phosphorus, ortho-phosphate, ammonia, nitrate, nitrite.
Table 2
Parameters required at each data point. While other parameters were optional (e.g., turbidity, water flow), for dataset completeness only the parameters listed here were used in this study.
| PARAMETER | DESCRIPTION |
|---|---|
| Date | When sample was taken |
| Location | Coordinates and/or site description |
| Nitrate concentration | Match sample to one of 7 colorimetric ranges |
| Phosphate concentration | Match sample to one of 7 colorimetric ranges |
| Water body Type | Choose from: stream, river, pond, lake, wetland, source |
| Land use | Choose from: agriculture, forest, grassland/shrub, urban residential, urban park, industrial, other (specify) |
| Vegetation | Choose from (more than one possible): trees/shrubs, grass, other (specify) |
| Pollution | 4 binary answers concerning presence of: foam, litter, algae, oily sheen |
| Colour | Choose from: colourless, yellow, green, brown, other (specify) |
Figure 1
Location of sampling sites from the 2019 and 2021 Water Blitz events in Luxembourg.
Figure 2
Distribution of observed nutrient concentrations.
Figure 3
Geographical distribution of observed nutrient concentrations combined for the 2019 and 2021 events.
Table 3
Scale of nitrate and phosphate concentrations in relation to surface water quality.
| INDICATOR | VERY GOOD | GOOD | MODERATE | UNSATISFACTORY | BAD |
|---|---|---|---|---|---|
| Nitrate-nitrogen (NO3–-N) [mg/l] | ≤2.3 | ≤5.7 | ≤11.3 | ≤22.6 | >22.6 |
| Phosphate-phosphorus (PO43–-P) [mg/l] | ≤0.033 | ≤0.163 | ≤0.326 | ≤0.653 | >0.653 |
Table 4
Pedigree matrix for nutrient data in fresh water.
| SCORE | PROXY | EMPIRICAL | METHOD | VALIDATION |
|---|---|---|---|---|
| 4 | Exact measure | Large sample set | Best available practice | Compared with independent measurements of same variable |
| 3 | Good fit | Small sample set | Reliable method | Compared with independent measurements of related variable |
| 2 | Well correlated | Modelled data | Acceptable method | Compared with measurements not independent |
| 1 | Poorly correlated | Educated guess | Unknown method | Indirect validation |
| 0 | No clear relation | Speculation | No rigor | No validation |
Table 5
Nutrient concentration summary for the combined data according to land use.
| LAND USE | #SAMPLES | MEDIAN NITRATE | # SAMPLES NITRATE ≥ 5 MG/L | % SAMPLES NITRATE ≥5 MG/L | MEDIAN PHOSPHATE |
|---|---|---|---|---|---|
| Urban residential | 84 | 2–5 | 23 | 27 | 0.05–0.1 |
| Urban park | 56 | 1–2 | 13 | 23 | 0.05–0.1 |
| Grassland/shrub | 84 | 2–5 | 30 | 36 | 0.02–0.05 |
| Agriculture | 77 | 2–5 | 31 | 40 | 0.02–0.05 |
| Forest | 116 | 2–5 | 49 | 42 | 0.02–0.05 |
Table 6
Nutrient concentration summary for the combined data for different water body types.
| TYPE | SAMPLES | MEDIAN NITRATE | MEDIAN PHOSPHATE |
|---|---|---|---|
| Stream | 215 | 2–5 | 0.02–0.05 |
| River | 127 | 2–5 | 0.1–0.2 |
| Pond | 52 | <0.2 | 0.02–0.05 |
| Lake | 12 | 0.5–1 | 0.02–0.05 |
| Wetland | 13 | <0.2 | 0.02–0.05 |
| Source | 9 | 2–5 | 0.02–0.05 |
Figure 4
Results for the Sauer.
Table 7
List of nutrient concentrations measured at AGE stations on the Sauer in 2019 and 2021.
| STATION LOCATION | DIST. [KM] | MEASUREMENT DATE 2019 | NITRATE [MG/L] | PHOSPHATE [MG/L] | MEASUREMENT DATE 2021 | NITRATE [MG/L] | PHOSPHATE [MG/L] |
|---|---|---|---|---|---|---|---|
| Martelange | 0 | 25.9 | 1.1 | 0.01 | 11.5 | 3.0 | 0.01 |
| Bigonville | 16 | 25.9 | 1.1 | 0.03 | 11.5 | 2.7 | 0.01 |
| Miserbreck | 20 | 26.9 | 1.1 | 0.01 | 12.5 | 2.5 | 0.01 |
| Esch/Sauer | 38 | 26.9 | 3.6 | 0.01 | 12.5 | 5.0 | 0.01 |
| Erpeldange | 73 | 16.9 | 3.0 | 0.05 | 25.5 | 4.3 | 0.02 |
| Reisdorf | 88 | 5.9 | 3.6 | 0.13 | 18.5 | 3.4 | 0.13 |
| Dillingen | 95 | 5.9 | 3.2 | 0.08 | 18.5 | 3.4 | 0.13 |
| Wasserbillig | 133 | 5.9 | 3.6 | 0.13 | 18.5 | 3.9 | 0.11 |
Figure 5
Results for the Alzette.
Table 8
List of nutrient concentrations measured at AGE stations on the Alzette in 2019.
| STATION LOCATION | DISTANCE [KM] | MEASUREMENT DATE | NITRATE [MG/L] | PHOSPHATE [MG/L] |
|---|---|---|---|---|
| Esch/Alzette | 0 | 16.10 | 1.9 | 0.17 |
| Schifflange | 5 | 16.10 | 1.6 | 0.17 |
| Huncherange | 9 | 16.10 | 2.3 | 0.26 |
| Hesperange | 20 | 17.10 | 3.2 | 0.31 |
| Eich | 34 | 23.10 | 4.3 | 0.14 |
| Walferdange | 39 | 23.10 | 3.9 | 0.19 |
| Mersch | 50 | 17.9 | 4.1 | 0.27 |
| Colmar Berg | 62 | 23.10 | 4.8 | 0.15 |
| Ettelbruck | 66 | 16.9 | 4.3 | 0.19 |