Distribution of aluminum and phosphorus fractions following alum treatments in a large shallow lake

Figures & data

Figure 1. Water column sampling and alum sediment core sites in GLSM on, respectively, 25 April and 9 August 2012.

Table 1. Mean total and dissolved Al concentrations (mg/L ± SD) and range at surface and bottom, inside and outside a 4000 ha mid-lake area treated with alum at 23.6 mg/L Al during 2–30 April 2012. Water samples for Al were collected on 25 April.

Lake treatment area	Total Al	Dissolved Al
Inside n = 8	2.08 ± 0.75 (1.0–2.95)	1.68 ± 0.74 (0.74–2.71)
Outside n = 14	1.69 ± 0.38 (1.18–2.60)	1.07 ± 0.7 (0.20–2.45)

Table 2. Mean sediment concentrations (± SD) of water, Al, Al-P, Ca-P, and Fe-P averaged over the top 6 cm (0–2, 2–4, and 4–6 cm) following alum treatments in 2011 (21.5 mg/L Al) and 2012 (23.6 mg/L Al) to a mid-lake 4000 ha area. Three cores were taken inside and 6 outside the treated area following the 2012 treatment (Fig. 1).

Lake treatment area	% Water	Al (mg/g)	Al (g/m^2)	Al-P (μg/g)	Ca-P (μg/g)	Fe-P (μg/g)
Inside n = 3	63.6 ± 1.4	18.52 ± 0.85	637 ± 41	226 ± 15	198 ± 20	33.0 ± 2
Outside n = 6	58.8 ± 8.5	13.76 ± 4.4	590 ± 171	161 ± 40	191 ± 30	38.4 ± 16