Table 2 Quality criteria and requirements for fulfillment

1

Moderate risk of bias

The study covered at least one complete annual cycle and included at least 12 sampling occasions evenly distributed in time

The hydrologic data obtained in the study was adequate for calculating hydraulic loads at inlet and outlet

There were no obvious deficiencies in the water balance

2

High sampling frequency

Samples were flow proportional composites or grab samples with a reasonably high sampling frequency (at least twice a month)

3

Hydraulic control

All major water flow paths were quantified and considered in the calculations of the outcomes

4

Removal processes quantified

At least one important removal process was quantified independently, and the result was reasonable in relation to the inlet/outlet difference

5

Effect modifiers

Sufficient information related to potential effect modifiers was reported

6

Replication

Replicate wetlands were studied, or the same wetland was studied for two or more complete annual cycles. If not reported it should be possible to calculate the variance of the replicates