Emissions of H₂S from Hog Finisher Farm Anaerobic Manure Treatment Lagoons: Physical, Chemical and Biological Influence

Round 1

Reviewer 1 Report

Manuscript is very good.

Author Response

No comments to respond to.

Reviewer 2 Report

This is an excellent paper which describes field measurement results on the hydrogen sulfide emissions from two anaerobic manure treatment lagoons. The variation in the emission rates of hydrogen sulfide and difference between two sites were well discussed with other parameters such as wind speed, water quality, bacterial activity and so on, and the conclusion was properly lead based on the discussions. So, I have no severe criticisms on the present manuscript. Before publication, please address following points.

• Abstract: Authors should describe the purpose of this study in the abstract to clearly show the value of this field experiments. Only methods and results were described in the present manuscript.
• Figure 1: Please contain a mark pointing north in Figure 1 a) and b).
• Figure 4: The solid line in Figure 4 (a) indicate the hog population. So, “population” is better instead of “depopulation” in the caption.
• Figure 7: Authors estimated the hydrogen sulfide liquid concentration based on the S content analysis and pH assuming no organic S. Is this reasonable? Considering pH and ORP, HS^- can be a dominant species in water of lagoons, I think. The organic S is one of the sources of hydrogen sulfide in the lagoon water. So, the assumption of no organic S is reasonable? Please confirm on this point.
• Table 5: Mean (g/hd^-1 d^-1) → Mean (g hd^-1 d^-1)

Author Response

• Abstract: Authors should describe the purpose of this study in the abstract to clearly show the value of this field experiments. Only methods and results were described in the present manuscript. Added “Hydrogen sulfide (H₂S) from hog operations contributes to noxious odors in the surrounding environment and can be life-threatening. There is, however, limited understanding of what influences H₂S emissions from these farms.”
• Figure 1: Please contain a mark pointing north in Figure 1 a) and b). Added
• Figure 4: The solid line in Figure 4 (a) indicate the hog population. So, “population” is better instead of “depopulation” in the caption. corrected
• Figure 7: Authors estimated the hydrogen sulfide liquid concentration based on the S content analysis and pH assuming no organic S. Is this reasonable? Considering pH and ORP, HS^-can be a dominant species in water of lagoons, I think. The organic S is one of the sources of hydrogen sulfide in the lagoon water. So, the assumption of no organic S is reasonable? Please confirm on this point. I have added clarification with 3 references concerning the assumption in the ‘Methods’ section and qualified this measurement as ‘Maximum potential’ H2S concentration.  Methods now reads: “Although the steady-state fraction of both total S and organic S in a lagoon depends on the hog feed [18,19], the fraction of organic S was expected to be relatively small compared to H₂S [2]. The maximum potential hydrogen sulfide concentration in the liquid samples was estimated from the sample S content and pH assuming no organic S [11].”
• Table 5: Mean (g/hd^-1d^-1) → Mean (g hd^-1 d^-1) corrected

 

Reviewer 3 Report

This work describes the influence of selected variables on the emissions of H₂S from hog finisher farm anaerobic manure treatment lagoons in 2 different localities. The authors consider both abiotic (winds, turbulences) and biotic factors (purple sulfur bacteria) in the elaboration of their work.

The work is well written and data and information are well organized.

Minor revisions:

Line 193-194: is the acronym PNSB or NPSB?

Line 332: a bracket is missed

Author Response

Line 193-194: is the acronym PNSB or NPSB? PNSB. corrected

Line 332: a bracket is missed, removed