Compared with NS condition, the concentrations of inorganic nitrogen (NH4+-N, NO3−-N and NO2−-N) and DON were both higher under HA, HS and HT conditions. The results were expected since the growth of nitrifying bacteria and denitrifying bacteria, as well as the nitrification reaction were inhibited under HA, HS and HT conditions , thus resulting in high levels of inorganic nitrogen and DON. The concentration of inorganic nitrogen under HM condition was almost the same with that Embelin under NS condition, while the concentration of DON was significantly lower, implying that heavy metal might favor the growth of anaerobic microorganisms and promote the degradation of DON.
3.2. MW distribution of SMPs
Molecular weight (MW) distribution of SMPs.MW (%)NSHAHSHMHTLow MW (%)a7075867484High MW (%)3025142616NS = normal state, HA = high ammonia content, HS = high salinity, HM = high level of heavy metal, HT = high temperature.aLow MW is defined as components eluted after 9.47 min (corresponding to MW = 15,000) and High MW before 9.47 min on gel permeation chromatography (Fig. 1).Full-size tableTable optionsView in workspaceDownload as CSV