Chemical surveillance in freshwaters: small sample sizes underestimate true pollutant loads and fail to detect environmental quality standard exceedances

Environmental Sciences Europe

Table 2 Data set characteristics of the selected data sets

Data set	Mean annual load	SD	Range	Skewness	Deviation from normality (p value)
Benzo(a)pyrene	4.58^a	3.73^a	22.0^a	2.70	4.55 × 10⁻⁸
4-tert-Octylphenol	233^a	68.0^a	314^a	− 0.02	0.89
Fluoranthene	13.1^a	16.0^a	94.0^a	3.41	3.33 × 10⁻¹¹
Fluoranthene, manipulated data set	8.71^a	4.02^a	20.0^a	0.72	1.17 × 10⁻³
DEHP 2007	1.51^b	0.79^b	4.69^b	1.97	1.02 × 10⁻⁵
DEHP 2008	1.18^b	0.64^b	2.48^b	0.96	2.71 × 10⁻⁴
DEHP 2010	0.68^b	0.40^b	2.04^b	1.35	2.9 × 10⁻⁴
DEHP 2016	0.58^b	0.25^b	1.16^b	0.32	0.43

All calculated values are based on the concentrations of 52 weekly composite samples. Variability is expressed as SD (standard deviation) and range. Normality was checked by the Shapiro–Wilk test (α = 0.05)
^ang/L
^bµg/L