Differential sensitivity of two green algae, Scenedesmus quadricauda and Chlorella vulgaris, to 14 pesticide adjuvants

Growth-inhibition tests for 14 pesticide adjuvants which are widely used to manufacture various pesticidal formulations in China, were performed on the green algae Scenedesmus quadricauda, and Chlorella vulgaris to compare differential sensitivity among populations of these algae to the adjuvants. The results showed that the acute toxicities of 700#, 1601#, By-140, and SOPA to S. quadricauda and C. vulgaris were the lowest among all the tested adjuvants. The acute toxicities of Tween 80, O-25, and AEO-13 phosphate to the selected two green algae were intermediate among the tested adjuvants. The acute toxicities of 602#, 500#, OT, NP-10, OP-10, and JFC were the highest. Meanwhile, the algal species vary widely in their response to those adjuvants. The results showed that there was a differential response to various adjuvants among the selected algal species and that the sensitivities of the various algal species exposed to 1601# and OT varied by nearly 1 order and to 700#, and By-140 varied by over 1 order of magnitude. In addition, the NOEC and LOEC values of the selected 14 adjuvants to S. quadricauda and C. vulgaris were tested; the result showed that NOEC < or = EC10相似文献   

Influence of chloride on silver uptake by two green algae, Pseudokirchneriella subcapitata and Chlorella pyrenoidosa

Silver bioavailability in the presence of chloride was estimated from short-term (< or = 60 min) uptake experiments with two green algae, Pseudokirchneriella subcapitata and Chlorella pyrenoidosa. In the first experiment, silver uptake was monitored under two concentration regimes in which total dissolved silver ([Ag]tot) and [Cl] were manipulated to maintain [Ag+] at a constant value (10 nM). Comparable uptake rates were measured for both treatments despite the dramatic changes in [Cl] and [Ag]tot. In the second experiment, ambient [Ag]tot was held constant (10 or 115 nM), but [Cl] was varied (0.005-50 mM) to explore the whole range of silver chloro-complexes. Intracellular silver varied markedly along the [Cl] gradient and exhibited a clear, positive correlation with ambient [Ag+] for both algae. We conclude that the biotic ligand model reliably describes silver bioavailability in the presence of chloride for the two test algae and that its applicability depends on the relative magnitudes of silver fluxes through the unstirred diffusion layer and across the cell membrane, with the latter being affected by the presence or absence of a Cu(I) transporter. In the presence of chloride, no evidence was found for the internalization of silver via anion transport or passive diffusion of the neutral mono-chloro-complex, AgCl0.     

Effects of chloramphenicol, florfenicol, and thiamphenicol on growth of algae Chlorella pyrenoidosa, Isochrysis galbana, and Tetraselmis chui

This study investigated the growth inhibition effects of three phenicol antibiotics on microalgae used in aquaculture. Different dose levels of chloramphenicol (CAP), florfenicol (FF), and thiamphenicol (TAP) were added to cultures of one freshwater green alga, Chlorella pyrenoidosa, and two marine algae, Isochrysis galbana and Tetraselmis chui. For the two marine algae, FF showed higher toxicity levels (EC50, 1.3-8 mg l(-1)) than CAP (4-41 mg l(-1)) and TAP (38-158 mg l(-1)). CAP was more toxic to the freshwater algae (EC50, 14 mg l(-1)) than FF (215 mg l(-1)) and TAP (1283 mg l(-1)). TAP was the least toxic to the three algae, but maintained the highest stability during the test period. Among the tested algae, T. chui was the species most sensitive to the three antibiotics. This study demonstrates that all three phenicol antibiotics can inhibit growth of the three microalgae and should be carefully used in aquaculture.     

Effects of organic solvents and solvent-atrazine interactions on two algae, Chlorella vulgaris and Selenastrum capricornutum

When assessing pesticides toxicity on test organisms, the use of organic solvents is frequently required to formulate solutions of pesticides having low or moderate water solubility. These solvents may influence the results of toxicity tests. This study examined the effects of ethanol and dimethyl sulfoxide (DMSO) on two species of algae, Chlorella vulgaris and Selenastrum capricornutum. The interactives effects of these organic solvents with various concentrations of atrazine were tested to analyse how these solvents can affect the toxicity of atrazine. Toxicity was measured as the change in chlorophyll (a) content (estimated via fluorescence) in cultures of the test organism that were incubated over a 96-h period at standard conditions of temperature and light. In the absence of atrazine, ethanol was toxic to both algae, yielding significant inhibition of chlorophyll (a) content at concentrations as low as 0.05%. Morever, S. capricornutum was less sensitive to ethanol than was C. vulgaris. DMSO did not show any toxic effects on either chlorophycea. At concentrations up to 0.5%, DMSO interacted additively with atrazine for both chlorophycea. An additive response was also observed with ethanol towards S. capricornutum. For C. vulgaris, ethanol interacted antagonistically at most of atrazine concentrations and gave few additive and synergistic interactions. An additive response of an atrazine-solvent mixture indicate the inherent toxicity of the atrazine. Since DMSO generally gave additive responses for both algae, it can be considered as an adequate organic solvent to use in bioassays.     

Phytochelatin induction, cadmium accumulation, and algal sensitivity to free cadmium ion in Scenedesmus vacuolatus

Phytochelatins are small, intracellular, metal-binding polypeptides produced by algae on exposure to increased metal concentration in their environment. The aim of the present study was to examine the relationship between phytochelatin concentration, bioaccumulated metal, and sensitivity of algal growth on cadmium exposure. For that purpose, intracellular cadmium concentration and thiol (glutathione, gamma-glutamylcysteine [gammaGluCys], and phytochelatins [PCn]) content were determined in the freshwater green alga Scenedesmus vacuolatus exposed to growth-inhibitory and noninhibitory concentrations of free Cd2+ in the range from 10(-14) to 10(-7) M. The algal growth rate was optimal up to a free Cd2+ concentration of 10(-9) M and then decreased by 40% at higher concentrations. The intracellular cadmium content increased sharply from 0.22 to 746 amol/cell over this free Cd2+ range. At the lowest Cd2+ concentration (control), glutathione was the only detectable thiol (127 amol/cell). With increasing Cd2+, formation of gammaGluCys and phytochelatins from PC2 to PC6 were observed. The predominant oligomer was PC3, with 42 amol/cell at the highest Cd2+ concentration (10(-7) M). The ratio of the concentration of total thiol groups to intracellular cadmium was important for maintaining optimal growth. In contrast, thiol groups from phytochelatins were never measured in excess to intracellular cadmium content.     

Effect of pesticides on blue-green algae and nitrogen-fixation

The effects of the pesticides, amitrol, a derivative of amitrol (viz. 3,5-diamino-1,2,4-triazole), diquat, paraquat, linuron, MCPA, malathion, and monuron, were studied on the nitrogen-fixing algae,Anabaena cylindrica, Aulosira sp.,Calothrix elenkenii, Chlorogloeae fritschii, Cylindrospermum muscicola, Nostoc sp. fromCollema tenax, Nostoc muscorum, Tolypothrix tenuis, andWestiellopsis sp. In general, two types of response were discernible; an initial period of depression succeeded by an increased activity and an initial period of depression followed by a distinct decrease on prolonged incubation. The results indicate that some pesticidal compounds can severely limit the nitrogen-fixing capacities of blue-green algae, thereby affecting the overall nitrogen economy of soils in general.     

酚酸类物质对铜绿微囊藻以及蛋白核小球藻的抑藻作用

目的研究单一以及复合酚酸对混合藻类的抑制作用。方法选用水杨酸、肉桂酸与焦性没食子酸单一或两两结合作用于铜绿微囊藻(Microcystis aeruginosa)与蛋白核小球藻(Chlorella pyrenoidosa)的复合体系,以叶绿素为生物量指标,计算其单一酚酸抑藻的半最大效应浓度(EC_(50)),判断其联合抑藻的复合效应。结果三种酚酸单独对铜绿微囊藻和蛋白核小球藻混合藻类均有一定抑制作用,抑制作用为焦性没食子酸水杨酸肉桂酸,实验第6 d,这三种酚酸单独对铜绿微囊藻和蛋白核小球藻混合体系抑制作用的EC_(50)依次为:7.87、64.90以及89.34 mg/L;复合酚酸对混合藻的抑制作用为焦性没食子酸与水杨酸组合焦性没食子酸与肉桂酸组合水杨酸与肉桂酸组合,前两种组合表现为协同抑藻作用,后一种组合的抑藻效应为相加作用。结论某些酚酸联合应用可协同抑藻,从而能减少其单一酚酸的使用量,具有相对较高的环境安全性。     

Toxicity of 40 herbicides to the green alga Chlorella vulgaris

The effects on the green alga Chlorella vulgaris of 40 herbicides in 19 different chemical structure classes and with 11 dissimilar modes of action were studied through 96-h acute toxicity tests. Experimental results indicated that the average acute toxicity of acetolactate synthase (ALS)-inhibiting herbicides to C. vulgaris was close to those of the acetyl-CoA carboxylase (ACCase)-inhibiting herbicides and the lipid synthesis-inhibiting protoporphyrinogen oxidase (Protox) inhibitor. Their acute toxicities were higher than those of the microtubule process inhibitor, mitotic process inhibitor, the glutamine synthase inhibitors, and 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSP synthase) inhibitors. The acute toxicities of auxin herbicides to C. vulgaris were the lowest among all herbicides tested and that of the photosynthesis-inhibiting herbicides was the highest.     

Toxicity of fluorotelomer carboxylic acids to the algae Pseudokirchneriella subcapitata and Chlorella vulgaris, and the amphipod Hyalella azteca

Perfluorinated acids (PFAs) have elicited significant global regulatory and scientific concern due to their persistence and global pervasiveness. A source of PFAs in the environment is through degradation of fluorotelomer carboxylic acids (FTCAs) but little is known about the toxicity of these degradation products. Previous work found that FTCAs were two to three orders of magnitude more toxic to some freshwater invertebrates than their PFA counterparts and exhibited comparable chain-length-toxicity relationships. In this study, we investigated the toxicity of the 6:2, 8:2, and 10:2 saturated (FTsCA) and unsaturated (FTuCA) fluorotelomer carboxylic acids to two species of freshwater algae, Chlorella vulgaris and Pseudokirchneriella subcapitata, and the amphipod, Hyalella azteca. C. vulgaris was generally the most sensitive species, with EC₅₀s of 26.2, 31.8, 11.1, and 4.2 mg/L for the 6:2 FTsCA, 6:2 FTuCA, 8:2 FTuCA, and 10:2 FTsCA, respectively. H. azteca was most sensitive to the 8:2 FTsCA and 10:2 FTuCA, with LC₅₀s of 5.1 and 3.7 mg/L. The toxicity of the FTCAs generally increased with increasing carbon chain length, and with saturation for most of the species tested, with the exception of P. subcapitata, which did not exhibit any trend. These observations agree with chain-length-toxicity relationships previously reported for the PFCAs and support the greater toxicity of the FTCAs compared to PFCAs. However, the toxicity values are approximately 1000-fold above those detected in the environment indicating negligible risk to aquatic invertebrates.     

Comparative sensitivity of sea urchin sperm bioassays to metals and pesticides

A simple sperm/fertilization bioassay, primarily using sea urchin gametes, has been developed and used by a variety of laboratories. This assay was recently refined into a standard test and is now being used by the U.S. Environmental Protection Agency and others for toxicity testing in marine waters. One factor that has lagged behind the development of this assay is the comparison of its sensitivity to various common toxicants as compared to other bioassay systems and life stages of other marine organisms. The objective of this study was to compare the sensitivity of a standardized sea urchin sperm/fertilization assay to the responses of embryo, larval, and adult marine organisms to metals (Ag, Cd, Cu, Pb, Zn) and pesticides (DDT, Dieldrin, Endrin, Endosulfan) added to natural seawater. The results, although highly variable, generally showed that sperm/fertilization and embryo assays were quite sensitive to the metals tested, but that the larval and adult assays were more sensitive to the pesticides. These comparative data, together with other studies of complex effluents, show that the standardized sperm/ fertilization bioassay is an especially quick and useful tool for biomonitoring of marine waters.Contribution No. 746, School of Fisheries, University of Washington, Seattle, Washington 98195.     

Differential responses of eight cyanobacterial and green algal species, to carbamate insecticides

In this study, five carbamate insecticides were subjected to 96 h acute toxicity tests to examine their effects on three cyanobacteria, Anabaena flos-aquae, Microcystis flos-aquae, and Mirocystis aeruginosa, and five green algae, Selenastrum capricornutun, Scenedesmus quadricauda, Scenedesmus obliquus, Chlorella vulgaris, and Chlorella pyrenoidosa. The average acute toxicity of the carbamate insecticides to the cyanobacteria and the green algae was in descending order carbaryl>carbofuran, propoxur, metolcarb > carbosulfan. Wide variations in response to the tested carbamate insecticides occurred among the eight individual species of cyanobacteria and green algae. The sensitivity of various species of algae exposed to carbofuran, propoxur, metolcarb, and carbaryl varied over one order of magnitude, and that of algae exposed to carbosulfan varied over two orders of magnitude. With regard to the diffrential sensitivity of cyanobacteria and green algae, the cyanobacteria were less sensitive than green algae to carbosulfan and propoxur. The pollutants may initiate a shift of algal group structure; especially, a shift from dominance by green algae to dominance by cyanobacteria, and may sustain cyanobacterial blooms at particular times. Therefore, the descending order of the ecosystem risk was carbosulfan > propoxur > carbofuran > carbaryl, metolcarb. There was a strong variance between toxicity and ecosystem risk; i.e., "low toxicity" does not imply "low ecosystem risk."