Table 6 Primary conclusions/observations of relevance to future research
Conclusions/observations | Comments |
|---|---|
• There is a need for additional studies of P plumes downstream from OWTSs that have been in use for long periods of time | • Such studies provide valuable examples of the development of P plumes over time |
• There is a need for additional studies performed in the vadose zone below OWTSs, preferably below facilities that have been in use for long periods of time | • Such studies could contribute to better estimates of the time frame regarding the process of P saturation • The studies should account for dilution • Oxalate-extractable iron and aluminium should be measured |
• Many studies are not replicated. In future research, study designs should strive for true replication whenever possible | • Unreplicated study designs make research results less valid and less usable; such studies cannot be included in regular meta-analyses |
• The reporting quality within the research field is often unsatisfactory. We recommend establishing reporting and study design standards | • This would improve the possibilities of critical evaluation, comparison, and compilation of study results |