A considerable number of studies have been conducted to investigate the effect of physical and chemical variables on the transport of nanoscale zerovalent iron (nZVI) in granular media. However, the role of soil grain size as a crucial factor in nanoparticle mobility is less understood. The present research work sought to examine the simultaneous effects of soil grain size and particle concentration on the transport of nZVI coated with carboxymethyl cellulose (CMC-nZVI), using saturated sand packed column experiments. To this end, a total of 12 tests were conducted by combining four different particle concentrations (C = 10, 200, 3000, 10,000 mg/l) and three grain sizes (dc = 0.297–0.5 mm, 0.5–1 mm, 1–2 mm). The effluent nZVI concentration and water pressure drop along the column were measured. The results showed that during the injection time, decreasing the grain size and increasing the particle concentration reduces the mobility of CMC-nZVI due to ripening phenomena, while during the flushing time (introducing deionized water), such changes in grain size and particle concentration increase the mobility of CMC-nZVI due to a release from the secondary energy minimum well (in the DLVO theory).

Successive applications of copper-based (Cu) fungicides have increased Cu concentration in vineyard soils, inducing Cu toxicity in young vines and cover crops such as black oat, thus inhibiting growth and development. However, increasing soil phosphorus (P) content can reduce Cu toxicity symptoms. In this context, the aim of this study was to evaluate the effect of Cu toxicity and its alleviation by P fertilization in black oat cultivated in sandy soil. For the experiment, Typic Hapludalf soil samples were air-dried, prepared, and subjected to increasing doses of Cu (0, 30, and 60 mg kg⁻¹) and P (0 and 100 mg kg⁻¹). Subsequently, the soil was incubated and stored in pots, where black oat seedlings were grown for 30 days in a greenhouse. Plant roots subjected to Cu, especially with the highest Cu concentration and without P addition decreased the root cap size, showing early tissue differentiation and lateral root formation near the apical region. Decrease in dry matter (DM) production of roots (50 %) and shoots (67 %) was also observed in the highest Cu concentration. Plants without P addition, regardless of Cu concentration, also had lower root (33 %) and shoot (65 %) DM production. P addition in soil and its increased concentration reduced root anatomical changes and stimulated plant DM production. Therefore, we conclude that excessive Cu concentration alters black oat root anatomical structure, affecting plant growth, especially in sandy soils with low organic matter content. However, P supply can reduce root Cu toxicity symptoms, thus increasing plant dry matter production.

In this paper, we present a simple methodological approach to assess the dissolution behaviour of residual light nonaqueous phase liquid (LNAPL) sources entrapped in saturated porous media and to estimate the actual risk to human health by water ingestion related to their presence in the subsurface. The approach consists of collecting experimental data on the release kinetics through lab-scale column tests and including these data in a modified version of the analytical model used to describe the groundwater ingestion pathway in risk analysis. The approach was applied to different test scenarios using toluene as a model compound and three types of porous media, i.e. glass beads and two sandy soils with slightly different textures. The experimental results showed that the concentration of toluene in the eluted water was far from the solubility value after a limited number of pore volumes. Furthermore, different behaviour was observed for the three types of porous media. In particular, higher residual saturation and a slower dissolution rate were observed for the soil characterized by the finest texture. This behaviour suggests that the release rate is inversely proportional to the total residual saturation due to the reduction in the porosity available for water flow and the permeability of the porous media. Using these data in a modified risk-based model showed that a remarkable reduction of the hazard index related to the water ingestion pathway can be achieved for a relatively high groundwater velocity and a small contamination source.

There is global concern about the effects of decabromodiphenyl ether (BDE209) on environmental and public health. The molecular properties, biosorption, degradation, accumulation, and cellular metabolic effects of BDE209 were investigated in this study to identify the mechanisms involved in the aerobic biodegradation of BDE209. BDE209 is initially absorbed by wall teichoic acid and N-acetylglucosamine side chains in peptidoglycan, and then, BDE209 is transported and debrominated through three pathways, giving tri-, hepta-, octa-, and nona-bromodiphenyl ethers. The C–C bond energies decrease as the number of bromine atoms on the diphenyl decreases. Polybrominated diphenyl ethers (PBDEs) inhibit protein expression or accelerate protein degradation and increase membrane permeability and the release of Cl⁻, Na⁺, NH₄⁺, arabinose, proteins, acetic acid, and oxalic acid. However, PBDEs increase the amounts of K⁺, Mg²⁺, PO₄³⁻, SO₄²⁻, and NO₃⁻ assimilated. The biosorption, degradation, accumulation, and removal efficiencies when Brevibacillus brevis (1 g L⁻¹) was exposed to BDE209 (0.5 mg L⁻¹) for 7 days were 7.4, 69.5, 16.3, and 94.6 %, respectively.

Reference materials are an indispensable element in the quality control of analytical results and procedures. Complicated natural matrices such as soil and sediment in the environment are subject to different processes. They are a source of various biochemical reactions, degradation, and biotransformation. Subject to these processes are all organic and inorganic pollutions which affect component parts of soil and sediment. The quantity and the composition of the organic and inorganic matter forming a given matrix, its origin, and the particle size fractions—all has an immediate influence on the content and the kind of pollution. The choice of the right reference material is a condition of the correct estimation of the reliability of the results. Many of the components forming the environmental matrix have influence on the content, stability, and homogeneity of the PCBs (e.g., the organic compound content and the percentage of minerals, particle size, moisture level). Reference material must be as similar as possible to real samples tested. Unfortunately, the majority of commercially available certified reference matrices for soils and bottom sediments containing polychlorinated biphenyls (PCBs) are not fully characterized as regards their makeup and the content of mineral and organic substances. Therefore, we face the question of matching (producing) appropriate CRMs for the tested matrices (samples of soils and sediments) to obtain dependable test results. Another solution to this problem could be creation of model compositions of soils and sediments with specific physical and chemical properties.

In order to enhance the oxidation and adsorption capacity of catalyst, two kinds of activated carbon (AC) are mechanically mixed with V₂O₅-WO₃/TiO₂ catalyst respectively. In this study, the mixtures (M-1: catalyst mixing with AC based on lignite; M-2: the one on coconut shell) are investigated to destroy high concentration (9.8 ng I-TEQ Nm⁻³) PCDD/Fs at low temperature (160 °C). Adding AC into the catalyst obviously increases removal efficiency (RE) and destruction efficiency (DE). However, M-2 presents higher RE value and lower DE value compared with M-1 at the same conditions as the stronger adsorption capacity of AC based on coconut shell. For the M-2 mixture, RE values are decreasing while DE values show an opposite trend with the ratios of catalyst to AC increasing. Oxygen plays a positive role on the destruction of PCDD/Fs by accelerating the conversion of V⁴⁺Oₓ and V⁵⁺Oₓ. Adjusting oxygen content from 0 to 20 % could increase the DE value from 27.4 to 82.2 % for the M-1 and from 15.8 to 68.9 % for the M-2. In the presence of ozone, a dark brown flock will be generated when the ratio of AC and catalyst is 4:1 due to the reaction between AC and ozone, which results in the lower RE and DE values. The RE and DE values reach the maximum of 96.3 %, 90.6 % in this paper, respectively, when the ratio of AC and catalyst is 1:1 with ozone. Finally, the regenerating of mixture is investigated. Most of dioxin residues in the mixture are desorbed and oxidized by catalysis at 200 °C in the presence of oxygen.

Previous pilot-scale studies have shown outstanding levels of efficiency in phosphorus removal by using hydrated oil shale ash (HOSA) sediments in horizontal subsurface flow (HSSF) filters with low greenhouse gas emissions. However, no long-term full-scale experiment has been conducted using this material. From September 2013 to December 2015, two HSSF filters with different hydraulic loading regimes (NH1 with a stable loading regime and NH2 with a fluctuating regime), used to treat municipal wastewater, were analysed to estimate greenhouse gas (GHG) fluxes and to develop a treatment system with minimised GHG emissions. The fluxes of CO₂, CH₄ and N₂O, as well as their emission factors were significantly lower when compared with studies where regular filter materials (sand, gravel, etc.) are in use. The fluctuating loading regime significantly increased CO₂ and N₂O fluxes (median values of −3.3 and 2.6 mg CO₂−C m⁻² h⁻¹, and 5.7 and 8.6 μg N₂O−N m⁻² h⁻¹ for NH1 and NH2 regimes, respectively), whereas no impact could be seen on CH₄ emissions (median 93.3 and 95.6 μg CH₄−C m⁻² h⁻¹, for NH1 and NH2, respectively). All GHG emissions were strongly affected by the chemical composition of the water entering into the system. The water purification efficiency of the system was satisfactory for most water quality parameters and excellent for phosphorus. Thus, the HOSA-filled filters have a good potential for municipal wastewater treatment with low GHG emission.

Selenium (Se) has long been known as an effective antagonist for counteracting mercury (Hg) and arsenic (As) toxicity in many animal and plant species. This study is the first to assess a low-dose Se additive as an in situ remediation tool for As- and Hg-contaminated gold mine tailing material. Mine tailing material from an 1860s gold mine stamp mill site was treated with different concentrations of sodium selenite (0, 0.5, 1, 3, 8, and 15 mg Se/kg). Reclamation grass seeds planted in each treatment showed significantly decreased plant toxicity with increasing [Se], as measured by increases in biomass, % emergence, and root lengths. Leachate was collected from each pot after the grass was harvested. The lowest Hg and As concentrations measured in the leachate were associated with the 1 mg Se/kg treatment (94 and 71 % lower than concentrations in leachate from untreated tailing material) and increased with lower and higher Se treatments. Finally, earthworms (Eisenia andrei) were introduced to the experimental treatments. Earthworm [Hg] decreased with increasing [Se], but this effect was confounded by differing [Hg] in the tailing material. Earthworm [As] decreased with [Se] up to 3 mg Se/kg, then earthworm [As] increased with tailing [Se]. This experiment confirms that low-dose selenium additions (up to 3 mg Se/kg tailing material) can have beneficial effects by limiting toxicity and mobility of As and Hg from the tailing material for both grass and earthworms.

Di-n-butyl phthalate (DBP) widely used as plastic films’ plasticizer, can cause agricultural pollution which is of increasing concern because of the food safety issues. Cucumber (Cucumis sativus Linn.), commonly cultured in greenhouse, was exposed to DBP stress to gain more information about the ecological risk of DBP in this study. Changes of DBP residues and fruit quality of cucumber at different DBP concentrations (0, 5, 10, 20, 40 mg/kg of dry soil) were investigated in pot experiments using an agricultural soil under greenhouse condition, respectively. DBP residue in cucumber fruits ranged from 0.5326 to 1.8938 mg/kg, and the quality of cucumber fruits (organic acids, vitamin C, soluble protein, and soluble sugar) were influenced by DBP stress. Moreover, the health risk assessment was evaluated by estimate daily intakes (EDI) and the target hazard quotient (THQ) was analyzed. Under 40 mg/kg DBP condition, the highest value of EDI was 2.49 μg/kg bw/day and the THQ ranged from 0.000700 to 0.0249. Although the risk of DBP in cucumber fruits was lower than the threshold limit value of risk, the potential health risk was not a negligible issue.

To provide growing population with sufficient food, greenhouse vegetable production has expanded rapidly in recent years in China and sustainability of its farming practices is a major concern. Therefore, this study assessed the sustainability of greenhouse vegetable farming practices from environmental, economic, and socio-institutional perspectives in China based on selected indicators. The empirical data were collected through a survey of 91 farm households from six typical greenhouse vegetable production bases and analysis of environmental material samples. The results showed that heavy fertilization in greenhouse vegetable bases of China resulted in an accumulation of N, P, Cd, Cu, Pb, and Zn in soil, nutrient eutrophication in irrigation water, and high Cd in some leaf vegetables cultivated in acidic soil. Economic factors including decreased crop yield in conventional farming bases, limited and site-dependent farmers’ income, and lack of complete implementation of subsidy policies contributed a lot to adoption of heavy fertilization by farmers. Also, socio-institutional factors such as lack of unified management of agricultural supplies in the bases operated in cooperative and small family business models and low agricultural extension service efficiency intensified the unreasonable fertilization. The selection of cultivated vegetables was mainly based on farmers’ own experience rather than site-dependent soil conditions. Thus, for sustainable development of greenhouse vegetable production systems in China, there are two key aspects. First, it is imperative to reduce environmental pollution and subsequent health risks through integrated nutrient management and the planting strategy of selected low metal accumulation vegetable species especially in acidic soil. Second, a conversion of cooperative and small family business models of greenhouse vegetable bases to enterprises should be extensively advocated in future for the unified agricultural supplies management and improved agricultural extension service efficiency, which in turn can stabilize vegetable yields and increase farmers’ benefits.