Bromide is commonly used as a tracer in studies of water and chemical transport in soil and rock because it is relatively nonreactive with soil and rock constituents and because of its low environmental background concentrations. Based on a largely ignored modification of an American Public Health Association standard colorimetric method for determining Br– using phenol red and chloramine-T(CT), we have corrected an internal error and recast the technique for use with 96-well microplates. Furthermore, the addition of thiosulfate to quench the undesirable chlorination reaction as previously published is shown to be unnecessary and even detrimental following the use of NH4+ to produce chloramine from excess Cl species. The method detection limit is 0.11 mg L–1 Br–; negative interference with dissolved organic C can be addressed by either standard additions or solid-phase extraction with C18 sorbent. By reducing the sample size from 300 to 20 µL, the concentration range can be expanded from 12 mg L–1 Br– to as much as 300 mg L–1 Br–.
We investigated the effect of binary mixtures of Zn, Cu, Cd, and Ni on the growth of a freshwater diatom Navicula pelliculosa. A 7 × 7 full factorial experimental design (49 combinations in total) was used to test each binary metal mixture. A 3‐d fluorescence microplate toxicity assay was used to test each combination. Mixture effects were predicted by concentration addition (CA) and independent action (IA) models based on single metal concentration‐response relationship between relative growth rate and the...
A novel method was proposed to determine biofouling potential by direct analysis of a reverse osmosis (RO) membrane through fluorescence intensity analysis of biofilm formed on the membrane surface, thereby incorporating fouling tendencies of both feedwater and membrane. Evaluation of the biofouling potential on the RO membrane was done by accelerated biofilm formation through soaking of membranes in high biofouling potential waters obtained by adding microorganisms and glucose in test waters. The biofilm formed...
We used 5 species periphytic algae to conduct toxicity assays of twenty herbicides. The 5 tested species represent riverine primary producers most likely to be affected by herbicides. A fluorescence microplate toxicity assay was used as an efficient and economical high‐throughput assay. Toxicity characteristics were analyzed, focusing on their relationship to herbicide mode of action (MoA). The relative differences between 50% and 10% effect concentrations depended on herbicide MoA, rather than tested species....
Silver nanoparticles (Ag‐NPs) are widely applied nowadays for their antibacterial activity. Their increasing use in consumer products implies that they will find their way into the environment via waste water treatment plants. It was the aim of the present study to compare the ecotoxicological impact of two differently designed Ag‐NPs using the solid contact test for the bacterial strain Arthrobacter globiformis. In addition, a miniaturized version of this test system was established which requires only small‐sized...
Microbial regrowth causes problems during water reuse. Comprehensive understanding of the microorganisms that can regrow in reclaimed water and their substrate requirements are necessary. In this study, potential regrowth organisms were isolated from seven water reclamation plants in Japan. Based on 16S rDNA analysis, the isolates were grouped into 34 operational taxonomic units, belonging to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes. Substrate...
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