Algicidal Effectiveness of Clearigate, Cutrine-Plus, and Copper Sulfate and Margins of Safety Associated with Their Use

Abstract

Laboratory studies of algicide toxicity to algal species provide information to improve the efficacy and efficiency of copper-containing algicides in actual field situations. The objectives of this study were (1) to measure the influence of copper form, initial concentration, and duration of exposure on the response of Raphidocelis subcapitata, a planktonic freshwater green alga; (2) to determine the contact time required for these copper-containing algicides (Clearigate, Cutrine-Plus, and copper sulfate) and the target species to obtain control; (3) to measure the critical burden of the three algicides required to obtain control of R. subcapitata; (4) to measure the residence time of the copper applied as the algicides in the water column of three waters having different water characteristics ( i.e., alkalinity, hardness, pH, and conductivity); and (5) to contrast exposures of copper (as algicides) required to control algae and the lower thresholds causing adverse effects on sensitive nontarget animal species. Algal control (EC(100)) was accomplished at 55.8, 117.5, and 187.5 microg Cu/L for CuSO(4), Cutrine-Plus and Clearigate with a contact time of 3 days in all cases. The critical burdens of copper (concentration sorbed by the algae) were 4.2, 7.3, and 7.9 microg Cu/mg algae (dry weight) for CuSO(4), Cutrine-Plus, and Clearigate, respectively. Because algicide toxicity generally decreases as cell density increases, the density of cells in algal blooms may hamper algicide effectiveness even at maximum label application rates. Determinations of critical burdens for algicides and target algal species provide necessary information to forecast the performance of algicide applications in field situations. The margin of safety ( i.e., the difference between the concentration where control of algae was obtained and the lower threshold concentration causing adverse effects on nontarget species) was greatest for Cutrine-Plus. However, the margins of safety are minimal (< 0, 12.5, and 82.5 microg Cu/L for Ceriodaphnia dubia exposed to CuSO(4), Clearigate, and Cutrine-Plus, respectively) when they are applied according to their labels.

Dynamics of metal availability and toxicity in historically polluted floodplain sediments

“…Differences in biodiversity, succession and total biomass were found, but these differences were not related to total or available copper concentrations. Also the functioning of the algal biofilm in terms of photosynthetic efficiency or primary production was not impaired on the polluted sediments, although copper blocks electron transport in PSII and is considered to be a very effective algaecide (Murray- Gulde et al, 2002). If the total amount of copper present in the sediment was available as free ions in the sediment pore water, concentrations would be more than 3 orders of magnitude higher than reported effect concentrations (Barranguet et al, 2000).…”

Contribution of Streptomyces in sediment to earthy odor in the overlying water in Xionghe Reservoir, China

“…These compounds are semi-volatile terpenoids produced as secondary metabolites by planktonic and benthic cyanobacteria, actinomycetes, fungi, and myxobacteria (Schulz et al, 2004;Wood et al, 1983). In an effort to eliminate these types of taste and odor compounds, many studies have been aimed at preventing the growth of cyanobacteria based upon the isolation and identification of odor-producing cyanobacteria and the conditions promoting their growth in natural lakes and ponds (Schrader et al, 2003;Murray-Gulde et al, 2002). However, the application of these preventive measures may not be appropriate in odorous waters where the organisms responsible for geosmin and 2-MIB production are not cyanobacteria.…”

EFFECTIVENESS OF DIQUAT, BOTH ISOLATED AND ASSOCIATED WITH COPPER SOURCES IN CONTROLLING THE Hydrilla verticillata SUBMERGED MACROPHYTES AND ANKISTRODESMUS Gracilis microphyte

“…From day 15 to 60 DAA a similar control behavior was observed in all concentrations (Table 3). Compared with the isolated diquat test, the final concentration of chlorophyll a was lower in this test, indicating that the presence of 1.0% copper hydroxide in the herbicide formulation increases the algaecide effect in the experimental unit, similar to copper sulphate, in 55.8, 117.5, and 187.5 μg L -1 concentrations (CuSO 4 ), to control Raphidocelis subcapitata (Murray-Gulde et al, 2002) and similar to diquat + 0.1% copper hydroxide, which was effective from 0.8 mg L -1 in controlling A. gracilis as well, with 0.32 μg L -1 chlorophyll a values (Garlich et al, 2016a).…”