The toxicity of engineered nanoparticles (ENPs) on bacteria has aroused much interest. However, few studies have focused on the effects of low-level ENPs on bacterial group behaviors that are regulated by quorum sensing (QS). Herein, we investigated the effects of nine ENPs (Ag, Fe, ZnO, TiO₂, SiO₂, Fe₂O₃, single-wall carbon nanotubes (SWCNTs), graphene oxide (GO), and C₆₀) on QS in Pseudomonas aeruginosa PAOl. An ENP concentration of 100 μg L⁻¹ did not impair bacterial growth. However, concentrations of 100 μg L⁻¹ of Ag and GO ENPs induced significant increases in 3OC₁₂–HSL in the culture and significantly promoted protease production and biofilm formation of PAO1. C₄–HSL synthase and its transcription factors were less sensitive to 100 μg L⁻¹ Ag and GO ENPs compared with 3OC₁₂-HSL. Fe ENPs induced a significant increase in the 3OC₁₂–HSL concentration, similar to Ag and GO ENPs. However, Fe ENPs did not induce any significant increase in protease production or biofilm formation. Different size distributions, chemical compositions, and aggregation states of the ENPs had different effects on bacterial QS. These whole circuit indicators could clarify the effects of ENPs on bacterial QS. This study furthers our understanding of the effects of low-level ENPs on bacterial social behaviors.

Most African countries have ratified the Stockholm Convention on persistent organic pollutants (POPs) and are expected to reduce emissions of POPs such as organochlorine pesticides (OCPs) to the atmosphere. Emerging evidence, however, suggests that there are contemporary sources of OCPs in African countries despite the global ban on these products. This study investigated the atmospheric contamination from OCPs in four West African countries—Togo, Benin, Nigeria, and Cameroon—to ascertain the emission levels of OCPs and the characteristic signatures of contamination. Polyurethane foam (PUF) disk passive air samplers (PAS) were deployed in each country for ca. 55 days in 2012 and analyzed for 25 OCPs. Hexachlorocyclohexanes (HCHs) and DDTs constituted the highest burden of atmospheric OCPs in the target countries, at average concentrations of 441 pg m⁻³ (range 23–2718) and 403 pg m⁻³ (range 91–1880), respectively. Mirex had the lowest concentration, ranged between 0.1 and 3.3 pg m⁻³. The concentration of OCPs in rainy season was higher than in dry season in Cameroon, and presupposed inputs from agriculture during the rainy season. The concentrations of ∑25 OCPs in each country were in the following order: Cameroon > Nigeria > Benin > Togo. There was significant evidence, based on chemical signatures of the contamination that DDT, aldrin, chlordane, and endosulfan were recently applied at certain sites in the respective countries.

Germanium (Ge) is widespread in the Earth’s crust. As a cognate element to silicon (Si), Ge shows very similar chemical characteristics. Recent use of Ge/Si to trace Si cycles and changes in weathering over time, growing demand for Ge as raw material, and consequently an increasing interest in Ge phytomining have contributed to a growing interest in this previously rather scarcely considered element in geochemical studies. This review deals with the distribution of Ge in primary minerals and surface soils as well as the factors influencing the mobility of Ge in soils including the sequestration of Ge in secondary mineral phases and soil organic matter. Furthermore, the uptake and accumulation of Ge in plants and effects of plant-soil relationships on the availability of Ge in soils and the biogeochemical cycling of Ge are discussed. The formation of secondary soil minerals and soil organic matter are of particular importance for the concentration of Ge in plant-available forms. The transfer from soil to plant is usually low and shows clear differences between species belonging to the functional groups of grasses and forbs. Possible uptake mechanisms in the rhizosphere are discussed. However, the processes that are involved in the formation of plant-available Ge pools in soils and consequently its biogeochemical cycling are not yet well understood. There is, therefore, a need for future studies on the uptake mechanisms and stoichiometry of Ge uptake under field conditions and plant-soil-microbe interactions in the rhizosphere as well as the chemical speciation in different plant parts.

This comparative study investigates pre-concentration/separation procedure for the magnetic solid phase extraction of Hg(II) species by a new green materials: naked magnetic chitosan flakes coated Fe₃O₄ micro-particles (NMCFs) and magnetic chitosan flakes coated Fe₃O₄ micro-particles embedded ethylenediaminetetraacetic-disodium (MCFs-EDTA-Na₂) in a batch process. The sorption procedure was optimized by using model solutions containing mercury(II) ions in chloride medium. The influence of experimental parameters like pH, time reaction, initial Hg(II) concentration, and ionic strength was investigated. The SEM micrograph indicates a good dispersion of magnetite micro-particles onto chitosan flakes. The FTIR spectrum reveals that EDTA-Na₂ moieties have been successfully cross-linked onto magnetic chitosan flakes. Vibration magneto-metric measurements confirm the paramagnetic (without remanence) behavior of NMCFs and MCFs-EDTA-Na₂. The experimental sorption data show that Hg(II) ions extraction yield decreases in acidic medium in both NMCFs and MCFs-EDTA-Na₂. The found optimum pH values are near 4.5 using NMCFs and 4.7 when the Hg(II) ion sorption occurs onto MCFs-EDTA-Na₂ micro-particles. The results also showed that Hg(II) ion sorption kinetic was very fast at the initial stage of contact time. The maximal sorption capacity was found to be 454 ± 13 mg g⁻¹, under optimum conditions, using NMCFs and 495 ± 14 mg g⁻¹ when MCFs-EDTA-Na₂ was used.

In this paper, a highly copper-resistant fungal strain NT-1 was characterized by morphological, physiological, biochemical, and molecular biological techniques. Physiological response to Cu(II) stress, effects of environmental factors on Cu(II) biosorption, as well as mechanisms of Cu(II) biosorption by strain NT-1 were also investigated in this study. The results showed that NT-1 belonged to the genus Gibberella, which exhibited high tolerance to both acidic conditions and Cu(II) contamination in the environment. High concentrations of copper stress inhibited the growth of NT-1 to various degrees, leading to the decreases in mycelial biomass and colony diameter, as well as changes in morphology. Under optimal conditions (initial copper concentration: 200 mg L⁻¹, temperature 28 °C, pH 5.0, and inoculum dose 10%), the maximum copper removal percentage from solution through culture of strain NT-1 within 5 days reached up to 45.5%. The biosorption of Cu(II) by NT-1 conformed to quasi-second-order kinetics and Langmuir isothermal adsorption model and was confirmed to be a monolayer adsorption process dominated by surface adsorption. The binding of NT-1 to Cu(II) was mainly achieved by forming polydentate complexes with carboxylate and amide group through covalent interactions and forming Cu-nitrogen-containing heterocyclic complexes via Cu(II)-π interaction. The results of this study provide a new fungal resource and key parameters influencing growth and copper removal capacity of the strain for developing an effective bioremediation strategy for copper-contaminated acidic orchard soils.

The remediation of heavy metal-contaminated soils is a great challenge and an important issue for global environmental sciences and engineering. Soil washing technology is popularly used for soil remediation, but there are issues that must be solved. These include selecting an environmentally friendly washing solution and preventing damage to the soil during the washing process. The aim of the present work is to reveal the effects of operational conditions on soil remediation contaminated by lead/cadmium, and the effects on soil physicochemical properties caused by the washing reaction. A loess soil sample was collected from northwestern China, and a humificated straw solution was used as the washing solution. The remediation efficiency was investigated using a small-scale experimental device. The remediation efficiency could be improved by optimizing the operational conditions, and we found that the Elovich equation fits better the reaction process compared to the double-constant equation and the first-order kinetics equation. The washing rate of cadmium was slightly faster than that of lead. Compared to the topsoil in the column, the concentration of lead/cadmium was higher in the bottom soil, and the content of lead/cadmium in the inner layer soil was lower than that in the outer layer soil. The washing process had little influence on the surface characteristics and functional groups of soil. The humificated straw solution could be used effectively to remove lead/cadmium and preserve nutrients in loess soil.

Optimizing the mono-cultivation and mixed cultivation of Chlamydomonas reinhardtii, Chlorella vulgaris, and an Ettlia sp. was evaluated for treating nitrate-contaminated groundwater and biomass production. Ettlia sp. showed the highest nutrient assimilation and growth rate among the three microalgae during bioremediation. Light-dark cycle was the effective condition for nutrient removal and COD mitigation by microalgae. Mixed microalgae with a larger presence of the Ettlia sp. exhibited the highest biomass productivity, nitrate-nitrogen, and phosphate-phosphorus removal rates of 0.21 g/L/d, 16.6, and 3.06 mg/L/d, respectively. An N:P mass ratio of 5 was necessary to increase the mixed-microalgal performance. The settling efficiency of the mixed microalgae increased up to 0.55 when using pH modulation during 30 min. Therefore, applying an Ettlia sp.-dominant consortium was the optimum strategy for the bioremediation of nitrate-contaminated groundwater in 3 days.

Two major concerns over the chemical industrial park (CIP) operations are high consumption of water resources and large amount of pollutant emissions. This study develops an interval chance-constrained programming model for industrial water resources management (ICCP-IWM) with consideration of multi-uncertainty and multi-environmental constraints. Uncertainties expressed as intervals and probability distributions are merged in the ICCP-IWM framework. The developed model is used to solve a real-world water resource management problem in the Shenyang Chemical Industrial Park to demonstrate its capacity and effectiveness, where the objective is to minimize the system cost of water pathways and pollutant-emission control under a series of constraints. Interval solutions with respect to water resources allocation, wastewater management, and pollutant emissions could be generated. Results indicate that a lower violation risk leads to an increased strictness of the constraints, then to a higher system cost; conversely, a higher violation risk results in a lower system cost, at the expense of an increase in the risk. These findings would be recommended by the decision-makers because of their applicability for practical decision process providing the optimal strategy for sustainable water resource management under multiple uncertainties.

System fluctuations of eco-industrial symbiosis network (EISN) organization due to disturbance are very similar to the controller adjustment in the automatic control theory. Thus, a methodology is proposed in this study to assess the vulnerability of EISN based on the automatic control theory. The results show that the regulator plays a key role to enhance the resilience of the network system to vulnerability. Therefore, it is imperative to strengthen the real-time regulation and control of EISN so that the system stability is improved. In order to further explore the impact of various regulations on the system vulnerability, the influence of system stability is simulated by means of proportional, differential, and integral control. A case study with Guigang eco-industrial park (EIP) was undertaken to test this model. The results showed that when the system was disturbed at different positions, the key nodes which had great influence on system vulnerability could be selected according to the magnitude of simulation curve. By changing the ratio coefficient of proportional, differential, and integral units to adjust the ecological chain network, the system’s resilience to vulnerability can be enhanced. Firstly, if basic conditions of EISN organization remain unchanged, the integral control of the policy support and infrastructure sharing should be strengthened. Secondly, the differential regulation should be improved continuously for the technological innovation capability of key node enterprises. Finally, the key chain filling projects should be introduced for proportional control so that the chain network design can be optimized from the source.

Given the rising nitrous oxide (N₂O) concentration in the atmosphere, it has become increasingly important to identify hot spots and hot moments of N₂O emissions. With field measurements often failing to capture the spatiotemporal dynamics of N₂O emissions, estimating them with modeling tools has become an attractive alternative. Therefore, we incorporated several semi-empirical equations to estimate N₂O emissions with the Soil and Water Assessment Tool from nitrification and denitrification processes in soil. We then used the model to simulate soil moisture and the N₂O flux from grassland soils subjected to long-term grazing (> 60 years) at different intensities in Alberta, Canada. Sensitivity analysis showed that parameters controlling the N₂O flux from nitrification were most sensitive. On average, the accuracy of N₂O emission simulations were found to be satisfactory, as indicated by the selected goodness-of-fit statistics and predictive uncertainty band, while the model simulated the soil moisture with slightly higher accuracy. As expected, emissions were higher from the plots with greater grazing intensity. Scenario analysis showed that the N₂O emissions with the recommended fertilizer rate would dominate the emissions from the projected wetter and warmer future. The combined effects of fertilization and wetter and warmer climate scenarios would increase the current N₂O emission levels by more than sixfold, which would be comparable to current emission levels from agricultural soils in similar regions.