Application of principal component analysis for the optimisation of lead(II) biosorption

Differential Zn and Mn sensitivity of microalgae species from genera Bracteacoccus and Lobosphaera

One of the most common pollutants in natural ecosystems is heavy metals. Algae are sensitive to the action of heavy metals. This allows to use algae to assess the toxicity of heavy metals, bioindication, and during phycoremediation. This study examines the effect of different Zn and Mn concentrations (1.0, 5.0, 25.0, 50.0, 500.0, 1000.0 mg L^-1) on green algae Bracteacoccus minor and Lobosphaera incisa in a chronic bioassay. The results of this study showed that the toxic effect of Zn and Mn on B. minor and L. incisa begins to manifest itself at the lowest of the studied metal concentrations-1 mg L^-1. The critical concentration of Zn, which leads to the complete death of B. minor and L. incisa, is 50.0 and 500.0 mg L^-1, and Mn is 1000.0 mg L^-1 and 500.0 mg L^-1, respectively. It was found that principal component (PC) 1 accounts for 60.47% of the total variance and reflects changes associated with low concentrations of heavy metals (up to 5.0 mg L^-1). PC2 accounts for 27.95% of the total variance. PC2 is mostly associated with high concentrations of ions of heavy metals. Thus, the effect of Zn and Mn concentrations up to 5 mg L^-1and above 50 mg L^-1on B. minor and L. incisa has a different character. At the same time, the response of the studied algae species to the action of Zn and Mn has individual differences. In general, B. minor is more resistant to Mn, while L. incisa is more resistant to Zn.

Principal component analysis reveals microbial biomass carbon as an effective bioindicator of health status of petroleum-polluted agricultural soil

We investigated a number of microbiological activities in the soil to serve as biomonitoring tools in assessing the ecotoxicity of diesel-contaminated soil samples during the different periods of bioremediation. Sawdust was used as the biostimulant for the biodegradation of artificial diesel-polluted soil samples. Soil microbial population, soil microbial enzymatic activities (catalase, lipase, dehydrogenase, urease, phosphatase and β-glucosidase), soil microbial biomass carbon (MBC), nitrogen (MBN) and phosphorus (MBP), soil microbial respirometric index and total petroleum hydrocarbon (TPH) concentration were monitored to evaluate the efficiency of the bioremediation process. After a period of 56 d, total petroleum hydrocarbon content reduced from 14,221 to 270 mg/kg. The parameter estimation using the nth-order kinetic model revealed that the first-order rate constants (k) for TPH removal were 4.417 d^-1 and 0.2670 d^-1 for sawdust-amended and unamended soil, respectively. This implied that, the sawdust amendment resulted in reaction rate 16.5 times faster than unamended soil. Thus, the biological indicators were generally more pronounced in biostimulated soil than the attenuated soil. However, to evaluate the efficiency of the sawdust-assisted bioremediation, principal component analysis, which was used in selecting the most sensitive bioindicators. It was observed that microbial biomass carbon, catalase, lipase and dehydrogenase were the most responsive bioparameters. A positive relationship between TPH removal and the four most sensitive bioparameters suggests that the use of four biological activities have proven to be effective monitoring tools for evaluating the efficiency of a bioremediation strategy.

Tolerance and sorption of Bromacil and Paraquat by thermophilic cyanobacteria Leptolyngbya 7M from Costa Rican thermal springs

We studied the adsorption ability and tolerance of the thermophilic filamentous cyanobacteria Letolyngbya 7M towards Paraquat and Bromacil. Adsorption isotherms at pH = 7.0 showed an adsorption capacity of 24.4 mg/g and 66.8 mg/g, respectively, and a good fit to the Langmuir model (R² = 0.97 and 0.99, respectively). To evaluate the effect of both herbicides on photosynthetic pigments and viability of cyanobacteria, cell autoflorescence and esterase activity was determined using flow cytometry. Autofluorescence was less sensitive to changes in cell viability, as it was only slightly reduced at high Paraquat and Bromacil concentrations. Herbicide effect on esterase activity is dose-dependent. Bromacil did not cause a significant effect on either chlorophyll a content or cell viability. This study demonstrates the potential of Leptolyngbya 7M to remove Paraquat and Bromacil herbicides from aqueous solution under laboratory conditions.

Chemometric Characterization of Synthetic Dye Sorption onto Slovakian River Sediments: A Laboratory Batch Experiment

The aim of the work was to characterize the sorption of cationic dyes thioflavine T (ThT) and methylene blue (MB) onto selected Slovakian river sediments using chemometric approaches including principal component analysis (PCA) and cluster analysis (CA). Also, the potential of mentioned multivariate analyses for comparison of studied objects (river sediments or river and model waters) as well as in finding relationships between the variables describing the physico-chemical characteristics of studied matrices or waters and sorption/desorption characteristics of matrices for dyes binding under laboratory conditions was evaluated. Parameters describing the physico-chemical characteristics of sediments include: pH, pHzpc, or cation-exchange capacity; and in the case of waters: pH, conductivity, water hardness, content of dissolved solids or presence of organic compounds. From the comparison of dye sorption onto sediments, it was found that sorption of thiazine dye MB was minimally 1.5-times higher than sorption of benzothiazole dye ThT. Sorption capacities Qs reached the maximum values in the case of sediments originated from Dudvah River (MB-Qs = 8.70 ± 0.42 mg g−1; ThT-Qs = 5.03 ± 0.28 mg g−1; ±SD). Obtained results showed that applied methods of multivariate analyses represent a suitable tool for evaluation of sorption/desorption processes of organic xenobiotics binding in sediments.