Complex sentence: These poor sequestration results have caused some, to suggest that ocean iron fertilization is not an effective carbon mitigation strategy "in general", however prior ocean fertilization experiments in high silica locations have observed much higher carbon sequestration rates because of diatom growth.
Split into simpler sentences: These poor sequestration results have caused some to suggest that ocean iron fertilization is not an effective carbon mitigation strategy in general. However, prior ocean fertilization experiments in high silica locations have observed much higher carbon sequestration rates because of diatom growth.