This paper illustrates the usefulness of pre-screening methods for an effective characterization of polluted sites. We applied a sequence of site characterization methods to a former Soviet military airbase with likely fuel and benzene, toluene, ethylbenzene, and xylene (BTEX) contamination in shallow groundwater and subsoil. The methods were (i) phytoscreening with tree cores; (ii) soil gas measurements for CH₄, O₂, and photoionization detector (PID); (iii) direct-push with membrane interface probe (MIP) and laser-induced fluorescence (LIF) sensors; (iv) direct-push sampling; and (v) sampling from soil and from groundwater monitoring wells. Phytoscreening and soil gas measurements are rapid and inexpensive pre-screening methods. Both indicated subsurface pollution and hot spots successfully. The direct-push sensors yielded 3D information about the extension and the volume of the subsurface plume. This study also expanded the applicability of tree coring to BTEX compounds and tested the use of high-resolution direct-push sensors for light hydrocarbons. Comparison of screening results to results from conventional soil and groundwater sampling yielded in most cases high rank correlation and confirmed the findings. The large-scale application of non- or low-invasive pre-screening can be of help in directing and focusing the subsequent, more expensive investigation methods. The rapid pre-screening methods also yielded useful information about potential remediation methods. Overall, we see several benefits of a stepwise screening and site characterization scheme, which we propose in conclusion.

Phytoremediation comprises a set of plant and microbe-based technologies for remediation of soil heavy metal contamination. In this work, four Pb-resistant bacteria (Agrobacterium tumefaciens, Rahnella aquatilis, and two Pseudomonas sp.) were selected among a collection of isolates from root nodule of Lens culinaris. They had a high degree of bioaccumulation ability in nutrient medium containing 2 mM Pb, and the maximum Pb accumulation of whole cell was found after 48-h incubation. These Pb-resistant bacteria synthesized plant growth promoting substances such as indole acetic acid and siderophore. The presence of the Pb resistance genes (pbrA) in these bacteria has been confirmed by PCR. L. culinaris cultivated in two experimental soils with different levels of contamination showed that Pb contamination affected plant growth; therefore, it’s co-inoculation with the consortium of Pb-resistant bacteria improved plant biomass. The present study demonstrated that lentil accumulated Pb primarily in their roots and poorly in their shoots; in addition, it’s co-inoculation in moderately Pb-contaminated soil induced a reduction in Pb accumulation in roots and shoots by 22 and 80 %, respectively. Whereas in highly Pb-contaminated soil, we registered a diminution in concentration of Pb in shoots (66 %) and an augmentation in roots (21 %). The contamination of soil by Pb caused an oxidative stress in lentil plant, inducing modulation in antioxidant enzymes activities, essentially in superoxide dismutase (SOD) and peroxidase (GPOX) activities which were more pronounced in lentil cultivated in highly Pb-contaminated soil, in addition, co-inoculation enhanced these activities, suggesting the protective role of enzymatic antioxidant against Pb-induced plant stress.Thus, the present study demonstrated that co-inoculation of lentil with A. tumefaciens, R. aquatilis, and Pseudomonas sp. formed a symbiotic system useful for phytostabilization of highly and moderately Pb-contaminated soils.

Naphthenic acids (NAs) are toxic constituents of oil sands process-affected water (OSPW) which is generated during the extraction of bitumen from oil sands. NAs consist mainly of carboxylic acids which are generally biorefractory. For the treatment of OSPW, ozonation is a very beneficial method. It can significantly reduce the concentration of NAs and it can also convert NAs from biorefractory to biodegradable. In this study, a factorial design (2⁴) was used for the ozonation of OSPW to study the influences of the operating parameters (ozone concentration, oxygen/ozone flow rate, pH, and mixing) on the removal of a model NAs in a semi-batch reactor. It was found that ozone concentration had the most significant effect on the NAs concentration compared to other parameters. An empirical model was developed to correlate the concentration of NAs with ozone concentration, oxygen/ozone flow rate, and pH. In addition, a theoretical analysis was conducted to gain the insight into the relationship between the removal of NAs and the operating parameters.

From screening 23 plant species, it was found that Pterocarpus indicus (C₃) and Sansevieria trifasciata (crassulacean acid metabolism (CAM)) were the most effective in polar gaseous trimethylamine (TMA) uptake, reaching up to 90 % uptake of initial TMA (100 ppm) within 8 h, and could remove TMA at cycles 1–4 without affecting photosystem II (PSII) photochemistry. Up to 55 and 45 % of TMA was taken up by S. trifasciata stomata and leaf epicuticular wax, respectively. During cycles 1–4, interestingly, S. trifasciata changed its stomata apertures, which was directly induced by gaseous TMA and light treatments. In contrast, for P. indicus the leaf epicuticular wax and stem were the major pathways of TMA removal, followed by stomata; these pathways accounted for 46, 46, and 8 %, respectively, of TMA removal percentages. Fatty acids, particularly tetradecanoic (C₁₄) acid and octadecanoic (C₁₈) acid, were found to be the main cuticular wax components in both plants, and were associated with TMA removal ability. Moreover, the plants could degrade TMA via multiple metabolic pathways associated with carbon/nitrogen interactions. In CAM plants, one of the crucial pathways enabled 78 % of TMA to be transformed directly to dimethylamine (DMA) and methylamine (MA), which differed from C₃ plant pathways. Various metabolites were also produced for further detoxification and mineralization so that TMA was completely degraded by plants.

High concentrations of chromophoric dissolved organic matter (CDOM) are terrestrially derived from upstream tributaries to Lake Taihu, China, and are influenced by hydrological conditions of the upstream watershed. To investigate how the dynamics of CDOM in Lake Taihu are influenced by upstream inflow runoff, four sampling cruises, differing in hydrological conditions, were undertaken in the lake and its three major tributaries, rivers Yincun, Dapu, and Changdou. CDOM absorption, fluorescence spectroscopy, chemical oxygen demand (COD), and stable isotope δ¹³C and δ¹⁵N measurements were conducted to characterize the dynamics of CDOM. The mean absorption coefficient a(350) collected from the three river profiles (5.15 ± 1.92 m⁻¹) was significantly higher than that of the lake (2.95 ± 1.88 m⁻¹), indicating that the upstream rivers carried a substantial load of CDOM to the lake. This finding was substantiated by the exclusively terrestrial signal exhibited by the level of δ¹³C (−26.23 ± 0.49‰) of CDOM samples collected from the rivers. Mean a(350) and COD in Lake Taihu were significantly higher in the wet season than in the dry season (t test, p < 0.0001), suggesting that the abundance of CDOM in the lake is strongly influenced by hydrological conditions of the watershed. Four components were identified by parallel factor analysis, including two protein-like components (C1 and C2), a terrestrial humic-like component (C3), and a microbial humic-like (C4) component. The contribution percentage of the two humic-like components relative to the summed fluorescence intensity of the four components (C ₕᵤₘᵢc) increased significantly from the dry to the wet season. This seasonal difference in contribution further substantiated that an enhanced rainfall followed by an elevated inflow runoff in the lake watershed in the wet season may result in an increase in humic-like substances being discharged into the lake compared to that in the dry season. This finding was further supported by an elevated a(250)/a(365) of CDOM samples collected in the lake in the wet season than in the dry season. Significantly higher mean levels of C3 and a(350) were recorded for CDOM samples collected from River Yincun than those from rivers Dapu and Changdou, differing in seasons, suggesting the significance of terrestrial CDOM input from River Yincun.

A permeable reactive barrier (PRB) was installed during 2005/2006 to intercept, capture and degrade a fuel spill at the Main Power House, Casey Station, Antarctica. Here, evaluation of the performance of the PRB is conducted via interpretation of total petroleum hydrocarbon (TPH) concentrations, degradation indices and most probable number (MPN) counts of total heterotroph and fuel degrading microbial populations. Results indicate that locations which contained the lowest TPH concentrations also exhibited the highest levels of degradation and numbers of fuel degrading microbes, based on the degradation indices and MPN methods selected. This provides insights to the most appropriate reactive materials for use in PRB’s in cold and nutrient-limited environments.

Cadmium is a ubiquitous carcinogenic pollutant with multiple biological effects. Both observational and experimental studies have suggested associations between cadmium and the rates of many types of cancers. The aim of the present study was to evaluate whether cadmium exposure is associated with nasopharyngeal carcinoma (NPC) in a population with a relatively high prevalence in southeast China. Hospital-based 134 NPC cases and 132 cancer-free controls were recruited from a cancer hospital in Chaoshan area, southeast of China. Basic clinical data and information of lifetime styles, smoking, and drinking as well as other demographic characteristics were also collected from medical records. Blood cadmium levels (BCLs) were detected by graphite-furnace atomizer absorption spectrophotometer (GFAAS). BCLs and over-limit ratios between cases and controls were compared. The relationships between BCLs and NPC were explored by comparing BCLs differences between/among different characteristics of related factors and logistic regression analysis. In addition, BCLs within cases were also compared in relation to the disease clinical stages, pathological types, and metastasis. The median concentration of blood cadmium in cases (3.84, interquartile range 2.21–6.10) was significantly higher than that of controls (2.28, interquartile range 1.79–3.45). The over-limit ratio (≥5 μg/L) in cases was also higher than that in controls (35.1 vs. 13.6 %, χ ² = 16.55, p < 0.001). Smokers tended to have high levels of cadmium burden, and smokers with longer smoking pack-years in cases had relatively higher BCLs (p = 0.001). NPC patients with diseases history presented lower cadmium burden (p = 0.020). In the NPC cases, BCLs were positively associated with clinical stages and N classification (r = 0.193, 0.187, respectively, p < 0.05). Cadmium seems to be a risk factor of NPC, and high cadmium exposure may promote the occurrence and development of NPC.

Currently, there is a growing emphasis on wastewater reclamation and reuse all over the world due to restricted water resources. Among a variety of wastewater reuse technologies, the use of microfiltration membranes (MF) is one of the popular processes because it has the ability to successfully eliminate particulates and colloidal matters. However, successful fouling control is not easy because effluents from the activated sludge process still contain small particulates and colloidal matters such as extracellular polymeric substance (EPS) and soluble microbial products (SMP). On the other hand, microbubbles have advantageous properties compared to common bubbles, but there hasn’t been reporting of the use of microbubbles in physical cleaning instead of aeration. Encouraging results were obtained herein through the application of microbubbles for physical cleaning. In evaluation of the cleaning efficiency, the efficiency of microbubbles was observed to be twice as high as that of aeration, except during the course of the initial 30 min. Total organic carbon (TOC) concentration of the membrane tank after treatment with microbubbles was more than twice as high as that after aeration for physical cleaning. The membrane cleaned with microbubbles also had the smoothest surface, with a roughness of 42.5 nm. In addition, microbubbles were found to effectively remove EPS and make the structure of the gel layer loose. In particular, the microbubbles had the ability to remove proteins through the effect of pyrolytic decomposition. Therefore, in FT-IR spectra of the membrane surfaces taken before and after physical cleaning, while each treatment showed similar peak positions, the peak values of the membrane treated with microbubbles were the lowest. Through various analyses, it was confirmed that microbubbles can remove foulants on the gel layer in spite of their very low shear force. This means that microbubble cleaning has full potential for use as a physical cleaning method in the wastewater reclamation process.

The sorption and retention processes play an important role in determining the bioavaibility and fate of trace elements in soils. Sorption and desorption of Pb²⁺, Zn²⁺, Ni²⁺, Cu²⁺, and Co²⁺ in three Tunisian Aridisols Calcorthids (AR1, AR2, and AR3) were studied using batch experiments. Sorption and retention capacities were determined by means of K ᵣ parameter and they were related to soil properties. The results showed that in all studied soils, K ᵣ values for Pb²⁺ and Cu²⁺ were higher than those of Zn²⁺, Ni²⁺, and Co²⁺ indicating that soils have higher affinity for the first ones. The high sorption and retention capacity of the three studied soils is ascribed to their alkaline pH and their high carbonates contents favoring the precipitation of these elements. Moreover, bivariate correlation analysis showed that sorption and retention of the studied cations was also strongly correlated with clay fraction and Fe oxides contents. All soils show high sorption irreversibility of Pb²⁺, Zn²⁺, Ni²⁺, Cu²⁺, and Co²⁺. The soils with highest sorption capacity show also the highest irreversibility.

Direct emissions of N₂O, CO₂, and CH₄, three important greenhouse gases (GHGs), from biological sewage treatment process have attracted increasing attention worldwide, due to the increasing concern about climate change. Despite the tremendous efforts devoted to understanding GHG emission from biological sewage treatment process, the impact of influent C/N ratios, in terms of chemical oxygen demand (COD)/total nitrogen (TN), on an anaerobic/anoxic/oxic (A/A/O) bioreactor system has not been investigated. In this work, the direct GHG emission from A/A/O bioreactor systems fed with actual sewage was analyzed under different influent C/N ratios over a 6-month period. The results showed that the variation in influent carbon (160 to 500 mg/L) and nitrogen load (35 to 95 mg/L) dramatically influenced pollutant removal efficiency and GHG production from this process. In the A/A/O bioreactor systems, the GHG production increased from 26–39 to 112–173 g CO₂-equivalent as influent C/N ratios decreased from 10.3/10.7 to 3.5/3.8. Taking consideration of pollutant removal efficiency and direct biogenic GHG (N₂O, CO₂, and CH₄) production, the optimum influent C/N ratio was determined to be 7.1/7.5, at which a relatively high pollutant removal efficiency and meanwhile a low level of GHG production (30.4 g CO₂-equivalent) can be achieved. Besides, mechanical aeration turned out to be the most significant factor influencing GHG emission from the A/A/O bioreactor systems.