The use of pesticides to increase agricultural production can result in the contamination of the environment, causing changes in the genetic structure of organisms and in the loss of biodiversity. This practice is also inducing changes in the rainforest ecosystem. In this work, a Pseudomonas aeruginosa isolated from a preservation soil area of the Brazilian Amazon Forest, without usage of any pesticide, was evaluated for its potential to degrade atrazine. This isolate presented all responsible genes (atzA, atzB, atzC, atzD, atzE, and atzF) for atrazine mineralization and demonstrated capacity to use atrazine as a nitrogen source, having achieved a reduction of 44 % of the initial concentration of atrazine after 24 h. These results confirm gene dispersion and/or a possible contamination of the area with the herbicide, which reinforces global concern of the increase and intensive use of pesticides worldwide.

When applied to agricultural soils, phosphate fertilizers and the mineral or organic compounds present in solid and/or liquid waste may raise phosphorus (P) content and increase soil P saturation. The degree of phosphorus saturation (DPS) is a good indicator of potential P loss from agricultural soils. The purpose of this study was to calculate the DPS of samples from an Oxisol amended for 5 years with biosolids and mineral fertilizer. DPS was calculated based on P, iron, and aluminum extracted by ammonium oxalate and oxalic acid (DPSₒₓ) or by Mehlich-1 solution (DPSM₁). Treatments included NPK mineral fertilization (175 kg ha⁻¹of P), B1 = 19.02 t ha⁻¹of biosolids (350 kg ha⁻¹of P), B2 = 38.17 t ha⁻¹of biosolids (703 kg ha⁻¹of P), B3 = 76.26 t ha–¹of biosolids (1,405 kg ha⁻¹of P), and a control (no P added). Water-extractable P (WEP) was also measured. Critical levels of DPSₒₓand DPSM₁(21 and 24 %, respectively) were only achieved in the topsoil (0–0.1 m) at the highest biosolid dose. Concentration of WEP was positively correlated to DPSₒₓand DPSM₁. The DPSM₁method may be an alternative to DPSₒₓfor assessing the environmental risk of P loss from soil into surface runoff.

The purpose of this study was to investigate adsorption characteristic of swine manure biochars pyrolyzed at 400 °C and 700 °C for the removal of Cu(II) ions from aqueous solutions. The biochars were characterized using BET surface area, Fourier transform infrared spectroscopy (FTIR), zeta potential, scanning electron microscopy/energy dispersive spectrometer (SEM–EDS), and X-ray diffraction (XRD). The adsorption of Cu(II) ions by batch method was carried out and the optimum conditions were investigated. The adsorption processes of these biochars are well described by a pseudo-second-order kinetic model, and the adsorption isotherm closely fitted the Sips model. Thermodynamic analysis suggested that the adsorption was endothermic. The maximum Cu(II) adsorption capacities of biochars derived from fresh and composted swine manure at 400 °C were 17.71 and 21.94 mg g⁻¹, respectively, which were higher than those at 700 °C. XRD patterns indicated that the silicate and phosphate particles within the biochars served as adsorption sites for Cu(II). The removal of Cu(II) ions from industrial effluent indicated that the fresh swine manure biochar pyrolyzed at 400 °C can be considered as an effective adsorbent.

Oxidative degradation of ofloxacin (OFX) by sulfate free radicals (SO₄ ⁻•) in the UV/Oxone/Co²⁺oxidation process was investigated for the first time, with a special focus upon identifying the transformation products as well as understanding the reaction pathways. Thirteen main compounds were identified after the initial transformation of OFX; the detailed structural information of which were characterized by high-performance liquid chromatography–high resolution mass spectrometry and MS fragmentation analysis. The degradation pathways mainly encompassed ring openings at both the piperazinyl substituent and the quinolone moiety, indicating that the usage of SO₄ ⁻• aided the oxidative degradation of OFX to undergo more facile routes compared to those in previous reports by using OH•/h⁺ as the oxidant, where the initial transformation attacks were mainly confined to the piperazine moiety. Moreover, in this study, smart control over the pH conditions of the oxidation system via different modes of Oxone dosage resulted in the selective degradation of the functional sites of OFX molecule, where it was shown that the SO₄ ⁻•-driven destruction of the quinolone moiety of OFX molecule favored the neutral pH conditions. This would be beneficial for the reduction of bacterial resistance against quinolones in the aqueous environment.

Several population studies relate exposure to high levels of arsenic with an increased incidence of ischemic heart disease and cardiovascular mortality. An association has been shown between exposure to high levels of arsenic and cardiovascular risk factors such as hypertension and diabetes mellitus, and vascular damage such as subclinical carotid atherosclerosis. The mechanisms underlying these phenomena are currently being studied and appear to indicate an alteration of vascular function. However, the effects of low levels of exposure to arsenic and their potential detrimental cardiovascular effect are less explored. The article provides an overview of the pathophysiologic mechanisms linking low-level arsenic exposure to the occurrence of cardiovascular disease and its complications, and some potential preventive strategies to implement.

We determined the distribution of polychlorinated biphenyls (PCBs), pentachlorobenzene (PeCBz), hexachlorobenzene (HxCBz), and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in surface sediments at 21 sites inside and outside Muroran Port, Japan. The concentration ranges and geometric means of PCBs (Σ209PCB), PeCBz, HxCBz, and PCDD/Fs and toxicity equivalence quantity (total TEQ) of dioxins inside Muroran Port were 1,100–65,000 (mean, 17,000) pg/g dw, 37–220 (100) pg/g dw, 31–810 (84) pg/g dw, 69–410 (170) pg/g dw, and 0.51–6.2 (2.3) pg TEQ/g dw, respectively. Their corresponding inventories inside Muroran Port were estimated to be 76, 0.31, 0.32, 0.55, and 7.8 g TEQ, respectively. The amounts of these pollutants were higher inside the port than outside the port and especially large in the inner part of the port. Most PCBs were homologues and congeners of penta- to hepta-chlorinated compounds, and the PCBs around Muroran Port were derived from technical PCBs, especially KC500 and KC600. As for PCDD/Fs, the influence of pentachlorophenol was significant, although pollution due to chloronitrofen and combustion was detected. The congeners of PCDD/Fs predominantly contributed to total TEQ. The concentration distributions of PeCBz, HxCBz, and PCDD/Fs and total TEQ were highly correlated with one another. This indicates that they are derived from the same combustion process.

Dissolved organic matter (DOM) affects arsenite [As(III)] toxicity by altering its sorption equilibrium at the cell wall interface. A better understanding of such mechanism is of great importance to assess As(III) ecotoxicity in aquatic systems. Batch experiments were conducted to study the effects of DOM on the regulation of As(III) sorption and toxicity in the diatom Navicula sp. The influence of humic acid (HA) on As(III) toxicity was assessed by measuring algal growth, chlorophyll a, and reactive oxygen species (ROS), whereas As(III) mobility across the cell wall was estimated by determining the concentration of intracellular, cell-wall-bound, and free As(III) ions in cell media. Results showed that the effects of HA on arsenite toxicity varied depending on various combinations of As(III)-HA concentrations. EC₅₀had an approximate threefold increase from 8.32 (HA-free control) to 22.39 μM (at 20 mg L⁻¹HA) when Navicula sp. was exposed to 1.0–100.0 μM of As(III), compared to an overall low complexation ratio of HA-As(III) in a range of 0.91–6.00 %. The cell wall-bound and intracellular arsenic content decreased by 19.8 and 20.3 %, respectively, despite the lower arsenite complexation (2.10 ± 0.16 % of the total As). Meanwhile, intracellular ROS was decreased by 12.6 % in response to 10.0 μM As(III) and 10 mg L⁻¹HA vs. the HA-free control. The significant contrast indicated that complexation alone could not explain the HA-induced reduction in arsenite toxicity and other factors including HA–cell surface interactions may come into play. Isotherms describing adsorption of HA to the Navicula sp. cells combined with morphological data by scanning electron microscopy revealed a protective HA floccule coating on the cell walls. Additional Fourier transform infrared spectroscopic data suggested the involvement of carboxylic groups during the adsorption of both HA and As(III) on the Navicula sp. cell surface. Collective data from this study suggest that cell wall-bound HA can moderate As(III) toxicity through the formation of a protective floccule coating occupying As(III) sorption sites and decreased effective functional groups capable of binding As(III). Our findings imply that As(III) toxicity can be alleviated due to the increased hindrance to cellular internalization of As(III) in the presence of naturally abundant DOM in water.

The remediation of copper-contaminated soils by aided phytostabilisation in 16 field plots at a wood preservation site was investigated. The mobility and bioavailability of four potentially toxic trace elements (PTTE), i.e., Cu, Zn, Cr, and As, were investigated in these soils 4 years after the incorporation of compost (OM, 5 % w/w) and dolomite limestone (DL, 0.2 % w/w), singly and in combination (OMDL), and the transplantation of mycorrhizal poplar and willows. Topsoil samples were collected in all field plots and potted in the laboratory. Total PTTE concentrations were determined in soil pore water (SPW) collected by Rhizon soil moisture samplers. Soil exposure intensity was assessed by Chelex100-DGT (diffusive gradient in thin films) probes. The PTTE phytoavailability was characterized by growing dwarf beans on potted soils and analyzing their foliar PTTE concentrations. OM and DL, singly and in combination (OMDL), were effective to decrease foliar Cu, Cr, Zn, and As concentrations of beans, the lowest values being numerically for the OM plants. The soil treatments did not reduce the Cu and Zn mineral masses of the bean primary leaves, but those of Cr and As decreased for the OM and DL plants. The Cu concentration in SPW was increased in the OM soil and remained unchanged in the DL and OMDL soils. The available Cu measured by DGT used to assess the soil exposure intensity correlated with the foliar Cu concentration. The Zn concentrations in SPW were reduced in the DL soil. All amendments increased As in the SPW. Based on DGT data, Cu availability was reduced in both OM and OMDL soils, while DL was the most effective to decrease soil Zn availability.

The influence of two neonicotinoids, i.e., imidacloprid (IMI) and acetamiprid (ACE), on soil microbial activities was investigated in a short period of time using a combination of the microcalorimetric approach and enzyme tests. Thermodynamic parameters such as QT(J g⁻¹soil), ∆Hₘₑₜ(kJ mol⁻¹), JQ/S(J g⁻¹ h⁻¹), k (h⁻¹), and soil enzymatic activities, dehydrogenase, phosphomonoesterase, arginine deaminase, and urease, were used to evaluate whole metabolic activity changes and acute toxicity following IMI and ACE treatment. Various profiles of thermogenic curves reflect different soil microbial activities. The microbial growth rate constant k, total heat evolution QT(expect for IMI), and inhibitory ratio I show linear relationship with the doses of IMI and ACE. QTfor IMI increases at 0.0–20 μg g⁻¹and then decreases at 20–80 μg g⁻¹, possibly attributing to the presence of tolerant microorganisms. The 50 % inhibitory ratios (IC₅₀) of IMI and ACE are 95.7 and 77.2 μg g⁻¹, respectively. ACE displays slightly higher toxicity than IMI. Plots of k and QTagainst microbial biomass-C indicate that the k and QTare growth yield-dependent. IMI and ACE show 29.6; 40.4 and 23.0; and 23.3, 21.7, and 30.5 % inhibition of dehydrogenase, phosphomonoesterase, and urease activity, respectively. By contrast, the arginine deaminase activity is enhanced by 15.2 and 13.2 % with IMI and ACE, respectively. The parametric indices selected give a quantitative dose-response relationship of both insecticides and indicate that ACE is more toxic than IMI due to their difference in molecular structures.

The establishment of an efficient surface water quality monitoring (WQM) network is a critical component in the assessment, restoration and protection of river water quality. A periodic evaluation of monitoring network is mandatory to ensure effective data collection and possible redesigning of existing network in a river catchment. In this study, the efficacy and appropriateness of existing water quality monitoring network in the Kabbini River basin of Kerala, India is presented. Significant multivariate statistical techniques like principal component analysis (PCA) and principal factor analysis (PFA) have been employed to evaluate the efficiency of the surface water quality monitoring network with monitoring stations as the evaluated variables for the interpretation of complex data matrix of the river basin. The main objective is to identify significant monitoring stations that must essentially be included in assessing annual and seasonal variations of river water quality. Moreover, the significance of seasonal redesign of the monitoring network was also investigated to capture valuable information on water quality from the network. Results identified few monitoring stations as insignificant in explaining the annual variance of the dataset. Moreover, the seasonal redesign of the monitoring network through a multivariate statistical framework was found to capture valuable information from the system, thus making the network more efficient. Cluster analysis (CA) classified the sampling sites into different groups based on similarity in water quality characteristics. The PCA/PFA identified significant latent factors standing for different pollution sources such as organic pollution, industrial pollution, diffuse pollution and faecal contamination. Thus, the present study illustrates that various multivariate statistical techniques can be effectively employed in sustainable management of water resources. Highlights • The effectiveness of existing river water quality monitoring network is assessed• Significance of seasonal redesign of the monitoring network is demonstrated• Rationalization of water quality parameters is performed in a statistical framework.