Copper (Cu) contamination has become a global concern because of industrial, agricultural, and other anthropogenic activities. In the present experiments, the toxicological effects, mechanisms, and potential toxicity thresholds were investigated in the roots of Vicia faba L. seedlings that were cultivated in Cu-amended soils (0, 6.25, 12.5, 25, 50, 100, 200, 400, and 600 mg kg⁻¹) for 20 days, based on an analysis of the soil physicochemical properties, native Cu, available Cu, and root-enriched Cu contents. The superoxide dismutase (SOD), ascorbate peroxidase (APX), and guaiacol peroxidase (POD) isozymes and activities, as well as glutathione (GSH) and heat shock protein 70 (HSP70), changed like biphasic dose-response curves, cooperating to control the redox homeostasis. The APX and POD enzymes exhibited enhanced activities and became H₂O₂ scavengers primarily when the catalase (CAT) activities tended to decrease. Endoprotease (EP) isozymes and activities might be enhanced to degrade carbonylated proteins and alleviate metabolic disturbance in the roots. Additionally, HSP70 may not be suitable as a biomarker for relatively higher soil Cu concentrations and relatively longer exposure times for the roots. As a result, the isozymes and activities of SOD, CAT, and EP, as well as GSH, can be adopted as the most sensitive biomarkers. The toxicity threshold is estimated as 0.76–1.21 mg kg⁻¹ of available Cu in the soils or 25.04–36.65 μg Cu g⁻¹ dry weights (DW) in the roots.

The occurrence and migration of heavy metal in coastal aquifer incorporating tidal effects were investigated in detail by the field geological survey and observation. The continuous groundwater sampling, field observation (for groundwater potentiometric surface elevation, pH, dissolved oxygen, temperature, and salinity), and laboratory analysis (for Cr, Ni, Cu, Zn, Cd, and Pb concentration) were conducted through eight monitoring wells located around the landfill in the northern part of Chongming Island, China. The results showed that the unconfined aquifer medium was estuary-littoral facies deposit of Holocene, mainly gray clayey silt and grey sandy silt, and the groundwater flow was mainly controlled by topography condition of the aquifer formation strike. The background values of Cr, Ni, Cu, Zn, Cd, and Pb in Chongming Island were 3.10 ± 3.09, 0.81 ± 0.25, 1.48 ± 1.09, 43.32 ± 33.06, 0.08 ± 0.16, and 0.88 ± 1.74 μg/L, respectively. Compared with the groundwater samples around the study area, the drinking water was qualified and was free from the seawater intrusion/estuarine facies contaminant encroachment. Pollutant discharge was reflected in water quality parameters, the Cr and Cu concentrations elevated to the peak of 50.07 and 46.00 μg/L, respectively, and meanwhile specific migration regularity was embodied in observation time series as well as other elements. This migration regularity was not fully identical according to correlations between these analyzed elements. Ambient watery environment, anthropogenic disturbance, regional hydrogeological condition, and biogeochemical reactivity on heavy metals reduced/altered the significance of elements correlation in the migration pathway in coastal aquifer.

This study aimed to determine the Pb⁺²adsorption capacities of hazelnut shell and activated carbon obtained from hazelnut shell. It also aimed to determine the effect of ZnCl₂in the activation process. The hazelnut was pyrolyzed at 250 and 700 °C. For determining the capture speed of the adsorbents, the pseudo-first- and second-order kinetic studies were performed. The Freundlich and Langmuir isotherm models were used to determine adsorption equilibrium. The surface characterization of hazelnut shell and activated carbon was determined by Brunauer-Emmett-Teller (BET) analysis and FTIR spectrum. Pb⁺²adsorption capacity of obtaining activated carbon was determined by ICP-OES analysis. The raw hazelnut shell’s BET surface area is 5.92 m²/g and the surface area of activated carbons which is pyrolyzed at 250 and 700 °C were determined (270.2 and 686.7 m²/g, respectively. The surface area of hazelnut shell, which pyrolyzed at 700 °C after being activated with ZnCl₂, was determined to be 736.49 m²/g. Results show that physical adsorption process is dominant for the activated carbon pyrolysis at 700 °C but the chemical adsorption is dominant for the activated carbon pyrolysis at lower degrees and for raw hazelnut shell.

A soil survey was conducted in urban areas from five sites, including Beijing, Baotou, Datong, Fuyang, and Xiantao in China. The objective was to explore the most significant factors that may impact the bioaccessibility of heavy metals (Bio-HMs), including As, Cr, Cu, Pb, and Zn, in soils. Twenty to 30 composite soil samples were collected at each site. The various soil properties, including pH, particle size, Fe/Mn, and organic matter contents, were analyzed. The chemical operated forms of HMs in soils were measured by the Bureau of Reference (BCR) sequential extraction scheme, while the Bio-HMs were determined by the simple bioaccessibility extraction test (SBET) procedure. The concentrations of total heavy metals (T-HMs) in soils from different sites (cities) were in the range as As (5.69–9.86), Cr (77.42–230.20), Cu (15.68–36.54), Pb (14.12–58.93), and Zn (38.66–183.46) mg/kg. Cu and Pb had higher relative bioaccessibilities (48–70 %) than those of As and Cr (6–15 %), indicating higher health risks of the former than the latter two HMs. The Bio-HMs for various HMs were comparable to the first two or three combined BCR extracted fractions, with an exception of Cu, whose Bio-HMs were larger than the combined three BCR fractions, indicating that Cu was highly accessible in soils as compared with other HMs. Factor analysis showed that all variables, including soil property parameters and BCR extracted fractions, could be represented by three common factors extracted with higher than 0.5 loadings and ∼80 % cumulative contribution to the total variance. Among the three common factors, factor 1, containing mainly pH, texture, and Fe/Mn variables, and factor 3, containing mainly organic matter variable, could be attributed to geographical regions, while factor 2, containing mainly BCR extracted fractions, could be ascribed to relative bioaccessibility of HMs (R-Bio-HMs). Interactive mapping of the main factors and cluster analysis were consistent, which supported the “site gathering” of the soil sample pools, suggesting that the Bio-HMs in soils in different geographical localities were site dependent.

We simultaneously measured bacterial production (BP), bacterial respiration (BR), alkaline phosphatase activity (phos) and ectoaminopeptidase activity (prot) in relation to biogeochemical parameters, nutritive resources and in situ temperature over a 1-year survey at the long-term observatory the SOLEMIO station (Marseille bay, NW Mediterranean Sea). Despite its proximity to the coast, oligotrophic conditions prevailed at this station (yearly mean of Chl a = 0.43 μg dm⁻³, NO₃ = 0.55 μmol dm⁻³ and PO₄ = 0.04 μmol dm⁻³). Episodic meteorological events (dominant winds, inputs from the Rhone River) induced rapid oscillations (within 15 days) in temperature and sometimes salinity that resulted in rapid changes in phytoplankton succession and a high variability in C/P ratios within the particulate and dissolved organic matter. Throughout the year, BP ranged from 0.01 to 0.82 μg C dm−³ h−¹ and bacterial growth efficiency varied from 1 to 39 %, with higher values in summer. Enrichment experiments showed that BP was limited most of the year by phosphorus availability (except in winter). A significant positive correlation was found between in situ temperature, BP, BR and phos. Finally, we found that temperature and phosphate availability were the main factors driving heterotrophic bacterial activity and thus play a fundamental role in carbon fluxes within the marine ecosystem.

Multidrug resistance of heterotrophic bacteria isolated from an aquaculture farm effluent in Parangipettai, at the southeastern coast of India, was investigated. In the initial screening, 27 antibiotic-resistant strains were isolated. All the strains were tested for antibiotic susceptibility against chloramphenicol with varying concentrations. From these, two highly resistant strains, i.e. S1 and S5, were isolated. The selected strains were identified by 16S ribosomal RNA (rRNA) sequencing techniques and confirmed as Bacillus pumilus and Bacillus flexus. Both the antibiotic-resistant strains were further utilized for multidrug susceptibility test by using various antibiotics. These two strains showed antibiotic resistance to 14 of 17 antibiotics tested. Both microdilution assay and well assay methods were used to determine the minimal inhibitory concentration (MIC) for the sensitive strains. Both the tests were shown to be almost similar. Our study highlights the occurrence of multidrug-resistant bacteria in the shrimp farm effluents.

Magnetite iron oxide (Fe₃O₄) nanoparticles (NPs) are key materials applied in many different fields of modern technology. The potential environmental impact of these NPs is of great concern. In this study, initially the effect of Fe₃O₄ NPs size (20 and 40 nm) as well as bulk (>100 nm) at 200 mg L⁻¹ on Picochlorum sp. (Trebouxiophyceae, Chlorophyta) is investigated during the different growth phases. The most inhibitory NPs were then chosen to assess their effects at different concentrations. The 20 nm NPs at 200 mg L⁻¹ were found to significantly reduce the viable cell concentration and chlorophyll a content during the exponential growth phase compared to the other particle sizes. However, the 20 nm NPs at different concentrations were found to promote algal growth during the late growth stages (stationary and decline phases) compared to the control. Additionally, algae were found to accelerate the aggregation and sedimentation of nanoparticles into the medium and therefore can be considered as potential organisms for bioremediation of nano-pollution.

Microelectrodes were used for real-time detection of hydrogen peroxide (H₂O₂) in a heterogeneous sono-Fenton system with ferrocene as the catalyst. The working mechanism of reactive blue 13 decolorization in a heterogeneous sono-Fenton system was investigated. Ultrasonic irradiation showed no effect on decolorization when used alone and did not enhance decolorization in the H₂O₂ system (43.0 % for H₂O₂ vs. 48.1 % for US+H₂O₂). However, a system with the presence of Fenton-like reagents achieved complete decolorization. Decolorization was greatly accelerated by the addition of ultrasonic irradiation. Thorough decolorization was achieved in 20 min in the heterogeneous sono-Fenton system, which was 30 min faster than in the heterogeneous Fenton system. Based on the data collected by microelectrodes, accelerated decomposition of H₂O₂ was also observed. Ultrasonic irradiation aided the ferrocene catalyst in liberating more •OH from Fenton reactions, leading to the faster decolorization.

The concentrations, composition profiles, and sources of polycyclic aromatic hydrocarbons (PAHs) were analyzed in 55 surface soil samples collected from four oil fields across China (Daqing, DQ; Shengli, SL; Xinjiang, XJ; and Huabei, HB). The total 16 priority PAHs concentrations of DQ, SL, XJ, and HB ranged from 857 to 27,816; 480 to 20,625; 497 to 43,210; and 12,112 to 45,325 ng/g, respectively, with means of 9160; 6394; 13,569; and 22,954 ng/g and the seven possible carcinogenic PAHs accounted for 8–25.7 % of the total PAHs. Almost all the samples were heavily contaminated, and phenanthrene, chrysene, and pyrene were the most dominant components. The PAH isomeric ratios indicated that PAHs in oil fields mainly originated from petroleum. The toxic assessment illustrated that people living and working in oil fields would suffer low carcinogenic risk, which was somehow coincided with the results of epidemiological survey on cancer incidence. It seems essential to pay more attention to the chronic human health effects of exposure to oil fields and to focus new studies on the public health field that involves a large number of people all over the world.

The objectives of this study were (1) to assess the responses of benthic nematodes to a polycyclic aromatic hydrocarbon (PAH) contamination and (2) to test bioremediation techniques for their efficiency in PAH degradation and their effects on nematodes. Sediments with their natural nematofauna communities from Bizerte lagoon (Tunisia) were subjected to a PAH mixture (100 ppm) of phenanthrene, fluoranthene, and pyrene during 30 days. Nematode abundance and diversity significantly decreased, and the taxonomic structure was altered. Results from multivariate analyses of the species abundance data revealed that PAH treatments were significantly different from the control. Spirinia parasitifera became the dominant species (70 % relative abundance) and appeared to be an “opportunistic” species to PAH contamination while Oncholaimus campylocercoides and Neochromadora peocilosoma were strongly inhibited. Biostimulation (addition of mineral salt medium) and bioaugmentation (inoculation of a hydrocarbonoclastic bacterium) were used as bioremediation techniques. Bioremediation treatments enhanced degradation of all three PAHs, with up to 96 % degradation for phenanthrene resulting in a significant stimulation of nematode abundance relative to control microcosms. Nevertheless, these treatments, especially the biostimulation provoked a weak impact on the community structure and diversity index relative to the control microcosms suggesting their feasibility in biorestoration of contaminated sediments.