This study analyses the seasonal trend of polychlorinated biphenyls (PCB) concentrations in air and soil from a high-altitude mountain pasture in the Italian Alps. PCB concentrations in soil were generally comparable to background levels and were lower than those previously measured in the same area. Only CB-209 unexpectedly showed high concentrations with respect to the other congeners. GC-MS-MS identification was very clear, rising a new problem of increasing PCB contamination concerning only CB-209, which is not present in commercial mixtures used in the past in Italy and Europe. Considering all of the congeners, seasonal PCB trends were observed both in air and in soil that were related to the temperature and precipitation measured specifically in the study area. Highly significant relationships were found between the temperature-normalised concentrations in soil and the precipitation amounts. A north/south enrichment factor was present only in soil with rapid early summer re-volatilisation kinetics from soil to air and autumn re-deposition events from air to soil. Fugacity ratio calculations confirmed these trends. Surface soils respond rapidly to meteorological variables, while subsurface soils respond much more slowly. Seasonal trends were different for the northern and southern sides of the mountain. A detailed picture of the interactions among temperature, precipitation, mountain aspects and soil features was obtained.

The response and detoxification mechanisms of three freshwater phytoplankton species (the cyanobacterium Aphanizomenon flos-aquae, the green alga Pediastrum simplex, and the diatom Synedra acus) to cadmium (Cd) were investigated. The cell growth of each species was measured over 10 days, and chlorophyll a fluorescence, Cd bioaccumulation (including surface-adsorbed and intracellular Cd), and phytochelatin (PC) synthesis were determined after 96-h exposures. The growth of the three phytoplankton species was significantly inhibited when Cd concentrations were ≥5 mg L⁻¹. Compared with P. simplex, greater growth inhibition in S. acus and A. flos-aquae occurred. The changes in chlorophyll fluorescence parameters including the maximal quantum yield of PSII (Fv/Fm) and relative variable fluorescence of the J point (Vj) demonstrated that the increase in Cd concentration damaged PSII in all three species. After 96-h exposures, the accumulation of surface-adsorbed Cd and intracellular Cd increased significantly in all three species, with the increase of Cd concentrations in the media; total cadmium accumulation was 245, 658, and 1670 times greater than that of the control in A. flos-aquae, P. simplex, and S. acus, respectively, after exposure to 10 mg L⁻¹. Total thiols exhibited a similar trend to that of Cd accumulation. PC₃ was found in A. flos-aquae and P. simplex in all Cd treatments. Glutathione (GSH) and PC₂ were also produced in response to exposure to high concentrations of Cd. PC₄ was only discovered at exposure concentrations of 10 mg L⁻¹ Cd and only in S. acus. The intracellular Cd/PCs ratio increased in all three phytoplankton with an increase in Cd concentrations, and a linear relationship between the ratio and the growth inhibition rates was observed with P. simplex and S. acus. Our results have demonstrated that metal detoxification mechanisms were dependent on the species. This study suggested that the variance of metal detoxification strategies, such as cadmium accumulation and PCs, might be an explanation why algal species have different sensitivity to Cd at various levels.

Secondary copper smelting (SeCu) is widely considered to be an important source of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs and PCDFs; PCDD/Fs). Laboratory experiments were performed using SeCu fly ash as a matrix for thermochemical reactions to investigate the effects of fly ash on the formation of PCDD/Fs and the potential mechanisms. Thermochemical reactions on SeCu fly ash over a temperature range of 250–450 °C and reaction times of 10–120 min caused the PCDD/F concentrations in the fly ash to increase significantly. The PCDD/F concentrations formed in the thermal reactions were about 99–139 times higher than the PCDD/F concentrations in the original fly ash, clearly indicating that fly ash promoted the formation of PCDD/Fs. The PCDFs dominated the PCDDs, and the PCDF/PCDD concentration ratio was about 30–40. Octachlorodibenzofuran (OCDF), octachlorodibenzo-p-dioxin, and the heptachlorodibenzofurans were the most dominant homologs that were formed. A comparison of the PCDD/F patterns produced in the thermochemical reactions and the patterns in the original fly ash suggested that the chlorination of less chlorinated PCDFs might be an important pathway in the formation of higher chlorinated furans. The results of this study indicated that SeCu fly ash has a high PCDD/F formation potential. It is crucial to have the fly ash filter at low temperature and that fly ash in the cooling system should be minimized.

With rapid response to environmental changes, phytoplankton communities have been used as a favorable bioindicator to evaluate environmental stress and anthropogenic impacts in aquatic ecosystems. The feasibility for their community-based bioassessment was studied in a mid-subtropical canal (Tiesha River), southern China, during a 1-year cycle (November 2009–December 2010). Samples were monthly collected at four sampling stations within a contamination gradient. Environmental variables, such as water temperature, dissolved oxygen (DO), chemical oxygen demand (COD), biological oxygen demand (BOD₅), total phosphorus (TP), and total nitrogen (TN), were measured synchronously for comparison with biotic parameters. The phytoplankton community structures showed a significant difference among four stations. The spatial variation in abundance was significantly correlated with the changes in environmental variables, especially TN, TP, and COD. Four dominant species (Aulacoseira granulata, Leptocylindrus danicus, Oscillatoria tenuis, and Radiococcus nimbatus) were significantly correlated with nutrients, while the species richness index represented a significant correlation with BOD₅. The phytoplankton-based Saprobien indices could not reveal the spatial variation in water quality status although may reflect water pollution levels (from β- to α-mesosaprobic zone) in the canal system. It is suggested that phytoplankton communities might be used as a potentially robust bioindicator for discriminating environmental quality status in mid-tropical canal systems.

Surface sediment grain size as well as the spatial distribution, pollution status, and source identification of heavy metals in the west Zhoushan Fishing Ground (ZFG) of the East China Sea were analyzed to study the geochemical background concentrations of heavy metals and to assess their potential ecological risk. Our results show that surface sediments in the eastern part of study area were mainly composed of sand-sized components. Spatial distributions of heavy metals were mainly controlled by grain size and terrigenous materials, and their concentrations in the coarsest grain sediments formed primarily during the Holocene transgressive period could represent the element background values of our study area. Contamination factor suggests that there was no pollution of Pb, Zn, and Cr generally in our study area and slight pollution of Cu, Cd, and As (especially Cu) at some stations. In addition, ecological harm coefficient indicates that the ecological risk of each heavy metal, except for Cd, at two stations was low as well. These results are consistent with the pollution load index and ecological risk index, which suggest both the overall level of pollution and the overall ecological risk of six studied metals in sediment were relatively low in our study area. Enrichment factor indicates that the heavy metals came mostly from the natural source. Summarily, the quality level of sediment in our study area was relatively good, and heavy metals in sediments could not exert threat to aquatic lives in the ZFG until now.

Cis-1,2,-dichloroethylene (cis-DCE) is a toxic, persistent contaminant occurring mainly as a daughter product of incomplete degradation of perchloroethylene (PCE) and trichloroethylene (TCE). This paper reports on abiotic reductive dechlorination of cis-DCE by mackinawite (FeS₁₋ₓ), a ferrous monosulfide, under variable geochemical conditions. To assess in situ abiotic cis-DCE dechlorination by mackinawite in the field, mackinawite suspensions prepared in a field groundwater sample collected from a cis-DCE contaminated field site were used for dechlorination experiments. The effects of geochemical variables on the dechlorination rates were monitored. A set of dechlorination experiments were also carried out in the presence of aquifer sediment from the site over a range of pH conditions to better simulate the actual field situations. The results showed that the suspensions of freshly prepared mackinawite reductively transformed cis-DCE to acetylene, whereas the conventionally prepared powder form of mackinawite had practically no reactivity with cis-DCE under the same experimental conditions. Significant cis-DCE degradation by mackinawite has not been reported prior to this study, although mackinawite has been shown to reductively transform PCE and TCE. This study suggests feasibility of using mackinawite for in situ remediation of cis-DCE-contaminated sites with high S levels such as estuaries under naturally achieved or stimulated sulfate-reducing conditions.

The organic carbon (OC) and elemental carbon (EC) collected by eight-stage air samplers over northern China during spring 2012 were determined to characterize the spatial variations, size distributions, and sources of carbonaceous aerosols. OC and EC had high concentration levels and spatial heterogeneity. Higher carbonaceous aerosol loadings were found in urban areas, and high concentrations of OC and EC were found in eastern parts of northern China, including Beijing, Taiyuan in Shanxi Province, Yucheng in Shandong Province, Xianghe in Hebei Province, and Shenyang in Liaoning Province. Except the Cele site, OC and EC at all the sites showed a bimodal distribution, peaking in the size of 0.4–0.7 and 4.7–5.8 μm. Carbonaceous aerosols in the fine mode in the urban areas are mostly presented in smaller sizes than those in the rural/regional background areas. For most sites, mass median aerodynamic diameter (MMAD) values in the fine particles for OC were higher than those for EC with the addition of semi-volatile organics. Good correlations between OC and EC in all the cities (5 in North China and 1 in northeast China) may suggest the impact of anthropogenic emissions on carbonaceous aerosols in the above regions.

Phytotoxic ozone (O₃) levels have been recorded in the Metropolitan Region of São Paulo (MRSP). Flux-based critical levels for O₃ through stomata have been adopted for some northern hemisphere species, showing better accuracy than with accumulated ozone exposure above a threshold of 40 ppb (AOT40). In Brazil, critical levels for vegetation protection against O₃ adverse effects do not exist. The study aimed to investigate the applicability of O₃ deposition model (Deposition of Ozone for Stomatal Exchange (DO₃SE)) to an O₃-sensitive tropical tree species (Psidium guajava L. ‘Paluma’) under the MRSP environmental conditions, which are very unstable, and to assess the performance of O₃ flux and AOT40 in relation to O₃-induced leaf injuries. Stomatal conductance (g ₛ) parameterization for ‘Paluma’ was carried out and used to calculate different rate thresholds (from 0 to 5 nmol O₃ m⁻² projected leaf area (PLA) s⁻¹) for the phytotoxic ozone dose (POD). The model performance was assessed through the relationship between the measured and modeled g ₛₜₒ. Leaf injuries were analyzed and associated with POD and AOT40. The model performance was satisfactory and significant (R ² = 0.56; P < 0.0001; root-mean-square error (RMSE) = 116). As already expected, high AOT40 values did not result in high POD values. Although high POD values do not always account for more injuries, POD₀ showed better performance than did AOT40 and other different rate thresholds for POD. Further investigation is necessary to improve our model and also to check if there is a critical level of ozone in which leaf injuries arise. The conclusion is that the DO₃SE model for ‘Paluma’ is applicable in the MRSP as well as in temperate regions and may contribute to future directives.

We studied the efficiency of water treatment by water hyacinth (Eichhornia crassipes) from heavy metals (Zn, Cd, Pb, Cu), as well as a possibility of using water hyacinth biomass obtained during treatment for vermicomposting by Eisenia fetida and the vermicompost quality in a model experiment. The results showed that the concentration of heavy metals in the trials with water hyacinth decreased within 35 days. We introduced water hyacinth biomass to the organic substrate for vermicomposting, which promoted a significant weight gain of earthworms and growth in their number, as well as a 1.5- to 3-fold increase in coprolite production. In the trial with 40 % of Eichhornia biomass in the mixture, we observed a 26-fold increase in the number and a 16-fold weight gain of big mature individuals with clitellum; an increase in the number of small individuals 40 times and in the number of cocoons 140 times, as compared to the initial substrate. The utilization of water hyacinth biomass containing heavy metals in the mixture led to a 10-fold increase in the number of adult individuals and cocoons, which was higher than in control. We found out that adding 10 % of Eichhornia biomass to the initial mixture affected slightly the number of microorganisms and their species diversity in the vermicompost. Adding Eichhornia biomass with heavy metals reduced the total number of microorganisms and sharply diminished their species diversity. In all trials, adding water hyacinth in the mixture for vermicomposting had a positive impact on wheat biometric parameters in a 14-day laboratory experiment, even in the trial with heavy metals.

Cultivars of hot pepper (Capsicum annuum L.) have different abilities to accumulate Cd in their fruits. Previously, we suggested that low-Cd cultivars take up more Cd, but can better prevent the Cd translocation from roots to aerial parts. However, the mechanisms involved in those processes are still unclear. In this study, we explored the roles of rhizosphere soil Cd fractions and root secretions of low molecular weight organic acids in the uptake, translocation, and accumulation of Cd in a low-Cd and high-Cd cultivar. The results showed that there was no significant difference in exchangeable Cd between rhizosphere soils of the two cultivars, which might be related to their similar root’s Cd uptake ability. The total content of low molecular weight organic acids released from roots of the low-Cd cultivar was almost equal to that released from roots of the high-Cd cultivar at the same Cd level; however, the composition of low molecular weight organic acids were determined by cultivars and Cd exposure levels. In the higher Cd (10 μM) treatment, the roots of the low-Cd cultivar excreted significantly less tartaric acid and more oxalic and acetic acids than those of the high-Cd cultivar. Additionally, there was no difference in the concentration of citric or succinic acid between the two cultivars. These results indicate that some kinds of low molecular weight organic acids efflux from hot pepper roots played an important role in the difference of Cd accumulation between low- and high-Cd cultivars.