The phrase "a concentration was" is correct and usable in written English.
It can be used when discussing the presence or level of a particular substance or quality in a specific context, such as scientific or analytical writing.
Example: "In the experiment, a concentration was measured to determine the effectiveness of the solution."
Alternatives: "a level of concentration was" or "a degree of concentration was".
Mixed macrophyte assemblages resulted in even stronger allelopathic effects than monocultured macrophytes; the biomass was reduced by 7 fold after 5 days using the mixed exudates and Chl a concentration was between 3 and 5 times lower.
When phytoplankton grew in water with exudates from monocultures, microalgal biomass was from 4 to 6 times lower than in the control after 5 days and Chl a concentration was up to 4 times lower.
A good linear relationship between the oxidation peak current and the bisphenol A concentration was found in the range of 2.0 × 10−7 ∼ 1.0 × 10−5 mol L−1, with a detection limit of 1.7 × 10−8 mol L−1.
The biomass (both above and below ground) and net photosynthesis rate was higher in high light than in the low light condition, but the chlorophyll a concentration was always higher in the low light condition than in the high light condition.
Interestingly, the chlorophyll a concentration was greater during the unsuccessful cultivation at almost all time points.
The chlorophyll a concentration was determined using the same biomass utilized for the extraction of phycobiliproteins.
Chlorophyll-a concentration was highly variable, both spatially and temporally.
An increase in DO concentration, accompanied by a decrease in water temperature and an increase in salinity and Chl-a concentration, was measured at sampling stations close to the typhoon track.
After 20 kg MLS were sprayed in the whole water pond (400 m2), the chlorophyll-a (Chl-a) concentration was decreased from 42 to 18 μg L−1 within 2 h and remained below 20 μg L−1 in the following 15 months, while the average Chl-a was 36 μg L−1 in the control pond throughout the experiment.
The conjugate (GNPs-Pep-A) concentration was measured using the GNP's concentration.
The EC was relatively low and the Chl-a concentration was high at the surface compared to those at the bottom.
