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Levels and distributions of polybrominated diphenyl ethers, hexabromocyclododecane, and tetrabromobisphenol A in sediments from Taihu Lake, China Full text
2016
The concentrations and distribution of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA) were investigated in 28 sediment samples collected from Taihu Lake, Eastern China. The results showed that all three classes of compounds were detected in 28 sediment samples but that PBDEs were the main contaminants in the study area. The total PBDE concentrations ranged from 3.77 to 347 ng/g dry weight (dw) with a mean value of 72.8 ng/g dw, whereas the concentrations ranged from 0.168 to 2.66 and from 0.012 to 1.30 ng/g dw for HBCD and TBBPA, respectively. In all of the sediment samples, BDE-209 was the predominant congener, accounting for 95.9 to 98.6 % of the total PBDEs, which indicated that commercial mixtures of deca-BDEs were the main sources of PBDE contamination. Higher concentrations of PBDEs were found in samples collected from Meiliang Bay and Gonghu Bay near the inflow river, which suggested that inflow runoff might play an important role in the PBDE levels in Taihu Lake sediments.
Show more [+] Less [-]Optimal growth condition of earthworms and their vermicompost features during recycling of five different fresh fruit and vegetable wastes Full text
2016
This study aimed to promote vermicomposting performance for recycling fresh fruit and vegetable wastes (FVWs) and to assess microbial population and community of final products. Five fresh FVWs including banana peels, cabbage, lettuce, potato, and watermelon peels were chosen as earthworms’ food. The fate test of earthworms showed that 30 g fresh FVWs/day was the optimal loading and the banana peels was harmful for the survival of Eisenia fetida. The followed vermicomposting test revealed lower contents of total carbon and weaker microbial activity in final vermicomposts, relative to those in compared systems without earthworms worked. The leachate from FVWs carried away great amounts of nutrients from reactors. Additionally, different fresh FVWs displayed dissimilar stabilization process. Molecular biological approaches revealed that earthworms could broaden bacterial diversity in their products, with significant greater populations of actinobacteria and ammonia oxidizing bacteria than in control. This study evidences that vermicomposting efficiency differs with the types and loadings of fresh FVWs and vermicomposts are rich in agricultural probiotics.
Show more [+] Less [-]Atmospheric pollutants in peri-urban forests of Quercus ilex: evidence of pollution abatement and threats for vegetation Full text
2016
García-Gómez, Héctor | Aguillaume, Laura | Izquieta-Rojano, Sheila | Valiño, Fernando | Àvila, Anna | Elustondo, David | Santamaría, Jesús M. | Alastuey, A. (Andrés) | Calvete-Sogo, Héctor | González-Fernández, Ignacio | Alonso, Rocío
Peri-urban vegetation is generally accepted as a significant remover of atmospheric pollutants, but it could also be threatened by these compounds, with origin in both urban and non-urban areas. To characterize the seasonal and geographical variation of pollutant concentrations and to improve the empirical understanding of the influence of Mediterranean broadleaf evergreen forests on air quality, four forests of Quercus ilex (three peri-urban and one remote) were monitored in different areas in Spain. Concentrations of nitrogen dioxide (NO₂), ammonia (NH₃), nitric acid (HNO₃) and ozone (O₃) were measured during 2 years in open areas and inside the forests and aerosols (PM₁₀) were monitored in open areas during 1 year. Ozone was the only air pollutant expected to have direct phytotoxic effects on vegetation according to current thresholds for the protection of vegetation. The concentrations of N compounds were not high enough to directly affect vegetation but could be contributing through atmospheric N deposition to the eutrophization of these ecosystems. Peri-urban forests of Q. ilex showed a significant below-canopy reduction of gaseous concentrations (particularly NH₃, with a mean reduction of 29–38 %), which indicated the feasibility of these forests to provide an ecosystem service of air quality improvement. Well-designed monitoring programs are needed to further investigate air quality improvement by peri-urban ecosystems while assessing the threat that air pollution can pose to vegetation.
Show more [+] Less [-]Interaction of arsenic species with tropical river aquatic humic substances enriched with aluminum and iron Full text
2016
de Oliveira, Lilian Karla | Melo, Camila de Almeida | Fraceto, Leonardo Fernandes | Friese, Kurt | Rosa, André Henrique
The mobility and bioavailability of arsenic (As) are strongly controlled by adsorption/precipitation processes involving metal oxides. However, the organic matter present in the environment, in combination with these oxides, can also play an important role in the cycle of arsenic. This work concerns the interaction between As and two samples of aquatic humic substances (AHS) from tropical rivers. The AHS were extracted as proposed by IHSS, and were characterized by ¹³C NMR. The experiments were conducted with the AHS in natura and enriched with metal cations, with different concentrations of As, and complexation capacity was evaluated at three different pH levels (5.0, 7.0, and 9.0). The AHS samples showed similar chemical compositions. The results suggested that there was no interaction between As(III) and AHS in natura or enriched with Al. Low concentrations of As(V) were bound to AHS in natura. For As(III), the complexation capacity of the AHS enriched with Fe was approximately 48 μmol per g of C, while the values for As(V) were in the range 69–80 μmol per grams of C. Fluorescence spectra showed that changes in Eh affected the complexation reactions of As(V) species with AHS.
Show more [+] Less [-]Heterotrophic microflora of highly alkaline (pH > 13) brown mud disposal site drainage water near Ziar nad Hronom (Banska Bystrica region, Slovakia) Full text
2016
Stramova, Zuzana | Remenar, Matej | Javorsky, Peter | Pristas, Peter
Brown mud is a waste by-product of alumina production by Bayer process. Due to extensive sodium hydroxide use in the process, brown mud disposal site near Ziar nad Hronom (Banska Bystrica region, Slovakia) and drainage water are ones of the greatest environmental burdens in Slovakia. Drainage water from this landfills has pH value higher than 13, and it contains many heavy metals and elevated salt content. In our experiments, relatively numerous bacterial population was detected in the drainage water with frequency of about 80 cfu/ml using cultivation approach. The alkalitolerant heterotrophic isolates were identified by combination of MALDI-TOF and 16S rDNA analysis. Drainage water population was dominated by Actinobacteria (Microbacterium spp. and Micrococcus spp.) followed by low G + C-content gram-positive bacteria (Bacillus spp.). Two isolates belonged to gram-negative bacteria only, identified as Brevundimonas spp. Phylogenetic and biochemical analyses indicate that nearly half of the bacteria isolated are probably representatives of a new species. Brown mud disposal site is proposed as a source of new bacterial taxa possibly used in bioremediation processes.
Show more [+] Less [-]Combinational effects of sulfomethoxazole and copper on soil microbial community and function Full text
2016
Liu, Aiju | Cao, Huansheng | Yang, Yan | Ma, Xiaoxuan | Liu, Xiao
Sulfonamides and Cu are largely used feed additives in poultry farm. Subsequently, they are spread onto agricultural soils together with contaminated manure used as fertilizer. Both sulfonamides and Cu affect the soil microbial community. However, an interactive effect of sulfonamides and Cu on soil microorganisms is not well understood. Therefore, a short-time microcosm experiment was conducted to investigate the interaction of veterinary antibiotic sulfomethoxazole (SMX) and Cu on soil microbial structure composition and functions. To this end, selected concentrations of SMX (0, 5, and 50 mg kg⁻¹) and Cu (0, 300, and 500 mg kg⁻¹) were combined, respectively. Clear dose-dependent effects of SMX on microbial biomass and basal respiration were determined, and these effects were amplified in the presence of additional Cu. For activities of soil enzymes including β-glucosidase, urease, and protease, clear reducing effects were determined in soil samples containing 5 or 50 mg kg⁻¹ of SMX, and the interaction of SMX and Cu was significant, particularly in soil samples containing 50 mg kg⁻¹ SMX or 500 mg kg⁻¹ Cu. SMX amendments, particularly in combination with Cu, significantly reduced amounts of the total, bacterial, and fungal phospholipid fatty acids (PLFAs) in soil. Moreover, the derived ratio of bacteria to fungi decreased significantly with incremental SMX and Cu, and principal component analysis of the PLFAs showed that soil microbial composition was significantly affected by SMX interacted with Cu at 500 mg kg⁻¹. All of these results indicated that the interaction of SMX and Cu was synergistic to amplify the negative effect of SMX on soil microbial biomass, structural composition, and even the enzymatic function.
Show more [+] Less [-]Photosynthesis performance, antioxidant enzymes, and ultrastructural analyses of rice seedlings under chromium stress Full text
2016
Ma, Jing | Lv, Chunfang | Xu, Minli | Chen, Guoxiang | Lv, Chuangen | Gao, Zhiping
The present study was conducted to examine the effects of increasing concentrations of chromium (Cr⁶⁺) (0, 25, 50, 100, and 200 μmol) on rice (Oryza sativa L.) morphological traits, photosynthesis performance, and the activities of antioxidative enzymes. In addition, the ultrastructure of chloroplasts in the leaves of hydroponically cultivated rice (O. sativa L.) seedlings was analyzed. Plant fresh and dry weights, height, root length, and photosynthetic pigments were decreased by Cr-induced toxicity (200 μM), and the growth of rice seedlings was starkly inhibited compared with that of the control. In addition, the decreased maximum quantum yield of primary photochemistry (Fv/Fm) might be ascribed to the decreased the number of active photosystem II reaction centers. These results were confirmed by inhibited photophosphorylation, reduced ATP content and its coupling factor Ca²⁺–ATPase, and decreased Mg²⁺–ATPase activities. Furthermore, overtly increased activities of antioxidative enzymes were observed under Cr⁶⁺ toxicity. Malondialdehyde and the generation rates of superoxide (O2̄) also increased with Cr⁶⁺ concentration, while hydrogen peroxide content first increased at a low Cr⁶⁺ concentration of 25 μM and then decreased. Moreover, transmission electron microscopy showed that Cr⁶⁺ exposure resulted in significant chloroplast damage. Taken together, these findings indicate that high Cr⁶⁺concentrations stimulate the production of toxic reactive oxygen species and promote lipid peroxidation in plants, causing severe damage to cell membranes, degradation of photosynthetic pigments, and inhibition of photosynthesis.
Show more [+] Less [-]Influence of selected environmental factors on the abundance of aerobic anoxygenic phototrophs in peat-bog lakes Full text
2016
Lew, Sylwia | Lew, Marcin | Koblížek, Michal
Aerobic anoxygenic phototrophs (AAPs) are photoheterotrophic prokaryotes that are widespread in many limnic and marine environments. So far, little is known about their distribution in peat-bog lakes. Seventeen peat-bog lakes were sampled during three summer seasons 2009, 2011, and 2012, and the vertical distribution of AAPs was determined by infrared epifluorescence microscopy. The analysis demonstrated that in the surface layers of the studied lakes, AAP abundance ranged from 0.3 to 12.04 × 10⁵ cells mL⁻¹, which represents <1 to 18.3 % of the total bacteria. The vertical distribution of AAPs confirmed their presence in the upper parts of the water column with minimum numbers in the anoxic bottom waters. We have shown that the AAP abundance was significantly positively correlated with the water pH, and the highest proportion of photoheterotrophs was found in peat-bog lakes with a pH between 6.7 and 7.6. Our results demonstrated an influence of water acidity on the abundance of AAPs, which may reflect a fundamental difference in the microbial composition between acidic and pH neutral peat-bog lakes.
Show more [+] Less [-]Photocatalytic ozonation of pesticides in a fixed bed flow through UVA-LED photoreactor Full text
2016
Radwan, Emad K | Yu, Linlong | Achari, Gopal | Langford, Cooper H.
In this study, a fixed bed flow through UVA-LED photoreactor was used to compare the efficiency of ozone, photocatalysis and photocatalysis-ozone degradation, and mineralization of two pure pesticides, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA), and a commercial one, Killex®. For the degradation of the parent compounds, ozone-based processes were more effective. While for mineralization, photocatalytic processes were more effective. Photocatalytic ozonation was the most efficient process for both the degradation and mineralization of the parent compounds. The degradation rates and mineralization by photocatalytic ozonation were higher than the summation of the corresponding rates by ozonation and photocatalysis, indicating a symbiotic relationship.Overall, the photocatalytic ozonation process with the fixed bed TiO₂ reduces the time needed for the degradation and mineralization of the pesticides, reduces the costs of powder catalyst separation and overcomes the reduced efficiency of immobilized catalysts, which makes the process quite attractive for practical applications.
Show more [+] Less [-]Plastic ingestion by Newell’s (Puffinus newelli) and wedge-tailed shearwaters (Ardenna pacifica) in Hawaii Full text
2016
Kain, Elizabeth C. | Lavers, Jennifer L. | Berg, Carl J. | Raine, André F. | Bond, Alexander L.
The ingestion of plastic by seabirds has been used as an indicator of pollution in the marine environment. On Kaua‘i, HI, USA, 50.0 % of Newell’s (Puffinus newelli) and 76.9 % of wedge-tailed shearwater (Ardenna pacifica) fledglings necropsied during 2007–2014 contained plastic items in their digestive tract, while 42.1 % of adult wedge-tailed shearwaters had ingested plastic. For both species, the frequency of plastic ingestion has increased since the 1980s with some evidence that the mass and the number of items ingested per bird have also increased. The color of plastic ingested by the shearwaters was assessed relative to beach-washed plastics by using Jaccard’s index (where J = 1 complete similarity). The color (J = 0.65–0.68) of items ingested by both species, and the type ingested by wedge-tailed shearwaters (J = 0.85–0.87), overlapped with plastic available in the local environment indicating moderate selection for plastic color and type. This study has shown that the Hawaiian populations of shearwaters, like many seabird species, provide useful but worrying insights into plastic pollution and the health of our oceans.
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