•Topramezone induced oxidative stress & mechanical damage to Chlorella vulgaris cells.•Pigment content and relative transcript of photosynthesis-related genes changed in topramezone exposed cells.•Photosynthetic system of algae cells disrupted.•Changes in morphology and membrane permeability induced by topramezone treatment.Topramezone is a new, highly selective herbicide of pyrazole structure for the post-emergence control of broadleaf and grass weeds in corn. In this study, the effects of topramezone on C. vulgaris, especially in relation to the cell growth, oxidative stress, cell morphology and photosynthetic activity were assessed. Results showed that topramezone treatment was detrimental to C. vulgaris growth during the 24–96 h of exposure. The changes in cells pigments content and relative transcript of photosynthesis-related genes, which implies that topramezone disrupted the photosynthetic system. Moreover, topramezone induced membrane permeability in a significant proportion of cells with a maximum damage rate of 40.40%, and morphology of cells was more complicated than the control group. TEM images also revealed that topramezone compromised the integrity of the cells. The data corroborated topramezone induced ROS triggered oxidative stress, leading to an increase of MDA. These results suggested that topramezone could have significant effects on growth and physiological functions in algae species, and we supposed that this herbicide affected all of these parameters and the observed effects can be explained by the generation of oxidative stress. This research helps to understand how topramezone affects C. vulgaris and provides a scientific basis for applications of topramezone in aquatic environment.

•Interaction of BSA with butachlor was studied by different spectroscopic methods.•Binding constant and number of binding site of butachlor with BSA were determined.•UV, CD, SFS and 3D fluorescence results revealed conformational changes in BSA.•The fluorescent quenching mechanism was static quenching.•Van der Waals force and hydrogen bond were the major types of interaction forces.Butachlor is an effective herbicide to deal with undesired weeds selectively and is used at high levels in Asian countries. However, its interaction and impairment effect on BSA was still not clear. In this study, we investigated the interaction between butachlor and bovine serum albumin (BSA) by multi-spectroscopic methods including UV absorption, circular dichroism (CD) spectra, Fourier transform infrared (FTIR) spectra and fluorescence spectra under physiological conditions (pH = 7.4). The results revealed that there was a static quenching of BSA induced by butachlor stemmed from the formation of complex. Based on thermodynamic data, the interaction of butachlor with BSA was due to happen, and van der Waals force as well as hydrogen bond were the major forces contributed to the interaction. The binding constant Kb and number of binding site of butachlor with BSA were 5.158 × 105 and 1.372 at 303 K, respectively. The distance r between donor (BSA) and acceptor (butachlor) was 0.113 nm, obtained according to the Förster theory. The results revealed that butachlor induced conformational changes in BSA but the secondary structure of BSA was still retained. In addition, the microenvironment around chromophore residues of BSA, for example, tryptophan, changed as well, resulting from the formation of more hydrogen bonds.

•CoFe2O4 NPs induce conformation changes in acid phosphatase.•Influence of Protein corona on the physicochemical properties of NPs and protein.•Cobalt Ferrite NPs influence the activity and kinetics of acid phosphatase.•Mechanism for sensing NPs in the environmental and biological samples was proposed.The present study explored the interaction and kinetics of cobalt ferrite nanoparticles (NPs) with acid phosphatase (ACP) by utilizing diverse range of spectroscopic techniques. The results corroborate, the CoFe2O4 NPs cause fluorescence quenching in ACP by static quenching mechanism. The negative values of van’t Hoff thermodynamic expressions (ΔH = −0.3293 J mol−1K−1 and ΔG = −3.960 kJ mol−1K−1) corroborate the spontaneity and exothermic nature of static quenching. The positive value of ΔS (13.2893 J mol−1K−1) corroborate that major contributors of higher and stronger binding affinity among CoFe2O4 NPs with ACP were electrostatic. In addition, FTIR, UV-CD, UV–vis spectroscopy and three dimensional fluorescence (3D) techniques confirmed that CoFe2O4 NPs binding induces microenvironment perturbations leading to secondary and tertiary conformation changes in ACP to a great extent. Furthermore, synchronous fluorescence spectroscopy (SFS) affirmed the comparatively significant changes in microenvironment around tryptophan (Trp) residue by CoFe2O4 NPs. The effect of CoFe2O4 NPs on the activation kinetics of ACP was further examined in Chlorella vulgaris. Apparent Michaelis constant (Km) values of 0.57 and 26.5 mM with activation energy values of 0.538 and 3.428 kJ mol−1 were determined without and with 200 μM CoFe2O4 NPs. Apparent Vmax value of −7 Umml−1 corroborate that enzyme active sites were completely captured by the NPs leaving no space for the substrate. The results confirmed that CoFe2O4 NPs ceased the activity by unfolding of ACP enzyme. This suggests CoFe2O4 NPs perturbed the enzyme activity by transitions in conformation and hence the metabolic activity of ACP. This study provides the pavement for novel and simple approach of using sensitive biomarkers for sensing NPs in environment.

•A direct mercury analyzer was used to estimate total organic carbon.•Mercury and organic carbon were measured in oxbow lake sediment cores.•Temporal and spatial deposition of Hg in the Mississippi Delta were evaluated.The purpose of this work was to study the feasibility of using a direct mercury analyzer (DMA) to simultaneously determine mercury (Hg) and organic matter content in sediment and soils. Organic carbon was estimated by re-weighing the sample boats post analysis to obtain loss-on-ignition (LOI) data. The DMA-LOI results were statistically similar (p < 0.05) to the conventional muffle furnace approach. A regression equation was developed to convert DMA-LOI data to total organic carbon (TOC), which varied between 0.2% and 13.0%. Thus, mercury analyzers based on combustion can provide accurate estimates of organic carbon content in non-calcareous sediment and soils; however, weight gain from moisture (post-analysis), measurement uncertainty, and sample representativeness should all be taken into account. Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed. Wetland sediments generally had higher levels of Hg than open water areas owing to a greater fraction of fine particles and higher levels of organic matter. Annual loading of Hg in open water areas was estimated at 4.3, 13.4, 19.2, 20.7, 129, and 135 ng cm−2 yr−1 for Beasley, Roundaway, Hampton, Washington, Wolf and Sky Lakes, respectively. Generally, the interval with the highest Hg flux was dated to the 1960s and 1970s.Comparison of LOI data obtained by a conventional method and by the DMA. The dark line represents a 1:1 ratio.

In this study, a simple, fast and reliable method for the simultaneous ICP-MS determination of Mg, Mn, Fe, Zn, Ag, Ba, Pb and Cr in edible vegetable oils using extraction induced by emulsion breaking is proposed. In the method, each sample of oil was emulsified with a Triton X-114 solution containing HNO3 and the emulsion was broken by centrifugation for 12 min at 6800 rcf, and then the acid aqueous phase deposited in the bottom of the centrifuge tube was collected for the determination of the metals of interest. The optimization of the method was performed by studying the effect of several parameters that could affect the extraction efficiency such as the concentrations of HNO3 and the emulsifying agents (Triton X-114 and Triton X-100) in the extractant solution, the centrifugal speed and the extraction time. The limits of detection and quantification for Mg, Mn, Fe, Zn, Ag, Ba, Pb and Cr were in the range of 0.004–0.271 μg L−1 and 0.013–0.903 μg L−1, respectively. The proposed method was applied in the determination of metals in eighty edible vegetable oil samples produced with different plants. The accuracy of the method was performed by spiking the samples with known amounts of the metals in the form of organometallic standards and the recoveries were in the range of 87–108%.

In this study, a simple, fast and reliable method for the simultaneous ICP-MS determination of Mg, Mn, Fe, Zn, Ag, Ba, Pb and Cr in edible vegetable oils using extraction induced by emulsion breaking is proposed. In the method, each sample of oil was emulsified with a Triton X-114 solution containing HNO3 and the emulsion was broken by centrifugation for 12 min at 6800 rcf, and then the acid aqueous phase deposited in the bottom of the centrifuge tube was collected for the determination of the metals of interest. The optimization of the method was performed by studying the effect of several parameters that could affect the extraction efficiency such as the concentrations of HNO3 and the emulsifying agents (Triton X-114 and Triton X-100) in the extractant solution, the centrifugal speed and the extraction time. The limits of detection and quantification for Mg, Mn, Fe, Zn, Ag, Ba, Pb and Cr were in the range of 0.004–0.271 μg L−1 and 0.013–0.903 μg L−1, respectively. The proposed method was applied in the determination of metals in eighty edible vegetable oil samples produced with different plants. The accuracy of the method was performed by spiking the samples with known amounts of the metals in the form of organometallic standards and the recoveries were in the range of 87–108%.