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Forewarning model for water pollution risk based on Bayes theory
2014
Zhao, Jun | Jin, Juliang | Guo, Qizhong | Chen, Yaqian | Lu, Mengxiong | Tinoco, Luis
In order to reduce the losses by water pollution, forewarning model for water pollution risk based on Bayes theory was studied. This model is built upon risk indexes in complex systems, proceeding from the whole structure and its components. In this study, the principal components analysis is used to screen out index systems. Hydrological model is employed to simulate index value according to the prediction principle. Bayes theory is adopted to obtain posterior distribution by prior distribution with sample information which can make samples’ features preferably reflect and represent the totals to some extent. Forewarning level is judged on the maximum probability rule, and then local conditions for proposing management strategies that will have the effect of transforming heavy warnings to a lesser degree. This study takes Taihu Basin as an example. After forewarning model application and vertification for water pollution risk from 2000 to 2009 between the actual and simulated data, forewarning level in 2010 is given as a severe warning, which is well coincide with logistic curve. It is shown that the model is rigorous in theory with flexible method, reasonable in result with simple structure, and it has strong logic superiority and regional adaptability, providing a new way for warning water pollution risk.
Afficher plus [+] Moins [-]Using Bayesian optimization method and FLEXPART tracer model to evaluate CO emission in East China in springtime
2014
Pan, X. L. | Kanaya, Y. | Wang, Z. F. | Tang, X. | Takigawa, M. | Pakpong, P. | Taketani, F. | Akimoto, H.
Carbon monoxide (CO) is of great interest as a restriction factor for pollutants related to incomplete combustions. This study attempted to evaluate CO emission in East China using the analytical Bayesian inverse method and observations at Mount Hua in springtime. The mixing ratio of CO at the receptor was calculated using 5-day source-receptor relationship (SRR) simulated by a Lagrangian Particle Dispersion Model (FLEXPART) and CO emission flux. The stability of the inversion solution was evaluated on the basis of repeated random sampling simulations. The inversion results demonstrated that there were two city cluster regions (the Beijing–Tianjin–Hebei region and the low reaches of the Yangtze River Delta) where the difference between a priori (Intercontinental Chemical Transport Experiment-Phase B, INTEX-B) and a posteriori was statistically significant and the a priori might underestimate the CO emission flux by 37 %. A correction factor (a posteriori/a priori) of 1.26 was suggested for CO emission in China in spring. The spatial distribution and magnitude of the CO emission flux were comparable to the latest regional emission inventory in Asia (REAS2.0). Nevertheless, further evaluation is still necessary in view of the larger uncertainties for both the analytical inversion and the bottom-up statistical approaches.
Afficher plus [+] Moins [-]Development of aquatic life criteria in China: viewpoint on the challenge
2014
Jin, Xiaowei | Wang, Yeyao | Giesy, John P. | Richardson, Kristine L. | Wang, Zijian
While more developed countries have a well-established systems to develop water quality criteria (WQC), little research has been done on the adequacy of the current WQC to protect endemic species of China. In order to maintain the health of aquatic ecosystems in China, a series of projects to establish national WQC based on regional characteristics has recently been initiated. However, the establishment of a completely novel methodology would be costly and time consuming. Also, due to the similarities in physiologies and natural histories of classes of aquatic organisms, there is no reason to believe that WQC would not be sufficient to protect unique species in China. This review was undertaken to identify key outstanding issues regarding establishment of aquatic life criteria (ALC) to be applied in China, including prioritization of chemicals, test species, mode of action, field/semi-field data, and methods of aggregating the information and calculating the ALC. This was used to identify the principle issues that need to be addressed in order to better understand the methods for development of criteria for the protection of aquatic life and provide a reference to China and other developing countries committed to the establishment of their own WQC system.
Afficher plus [+] Moins [-]Carbonyl compounds and dissolved organic carbon in rainwater of an urban atmosphere
2014
Balla, D. | Papageorgiou, A. | Voutsa, D.
This study investigates the occurrence of carbonyl compounds in rainwater at the city of Thessaloniki, Northern Greece. The concentrations of carbonyl compounds (as sum of 14 compounds) ranged from 21.8 to 592 μg/L, mean concentration 119 μg/L. Formaldehyde, acetaldehyde, hexanal, glyoxal, and methylglyoxal were the dominant compounds. DOC concentrations in rainwater ranged from 0.46 to 21.3 mg/L. UV–Vis and fluorescence spectra characteristics showed variation among rain events. Carbonyl compounds were negatively correlated with temperature exhibited relatively higher concentrations in cold season. They also influenced by storm origin with higher concentrations under terrestrial air masses. Calm conditions enhance the concentrations of DOC. Wash out is an effective removal mechanism of DOC.
Afficher plus [+] Moins [-]Enhanced bioaccumulation of pentachlorophenol in carp in the presence of multi-walled carbon nanotubes
2014
Sun, Hongwen | Ruan, Yuefei | Zhu, Hongkai | Zhang, Zhiyan | Zhang, Yanwei | Yu, Li
The impact of suspended particles on the bioavailability of pollutants has long been a controversial topic. In this study, adsorption of pentachlorophenol (PCP) onto a natural suspended particulate matter (SPM) and multi-walled carbon nanotubes (MWCNTs) was studied. Facilitated transports of PCP into carp by SPM and MWCNTs were evaluated by bioaccumulation tests exposing carp (Carassius auratus red var.) to PCP-contaminated water in the presence of SPM and MWCNTs, respectively. Desorption of PCP on SPM and MWCNTs in simulated digested fluids was also investigated. The results demonstrate that MWCNTs (KF = 7.99 × 10⁴) had a significantly stronger adsorption capacity for PCP than the SPM (KF = 19.0). The presence of SPM and MWCNTs both improved PCP accumulation in the carp during the 21 days of exposure, and the 21 days PCP concentration in the carp was enhanced by 25.9 and 12.8 % than that without particles, respectively. The enhancement in bioaccumulation by MWCNTs was less than that by the SPM. Considerably more PCP was accumulated in the viscera of the fish (BCF = 519495 for SPM and 148955 for MWCNTs), and the difference in PCP concentrations between different tissues became greater with particles. PCP desorption in the simulated digestive fluids was faster than that in the background solution. Compared to MWCNTs-bound PCP, more SPM-bound PCP was desorbed, and KFof desorption for SPM was at least 4 orders of magnitude higher than that for MWCNTs, which can explain the greater enhancement in bioaccumulation in the presence of SPM. Particle-bound pollutants might pose more risk than pollutants alone.
Afficher plus [+] Moins [-]Metals bioaccumulation and histopathological biomarkers in Carcinus maenas crab from Bizerta lagoon, Tunisia
2014
Ben-Khedher, Sana | Jebali, Jamel | Houas, Zohra | Nawéli, Hmida | Jrad, Amel | Banni, Mohamed | Boussetta, Hamadi
Metals concentrations and histolopathological lesions of gills and digestive gland were investigated in Carcinus maenas crabs sampled from Bizerta Lagoon and Kuriat Island (Tunisia) as control site. The concentrations of trace metals varied between tissues, sites and sampling time. The highest levels of the analysed metals in gills and digestive gland were noted in Menzel Bourguiba and Cimentery sites at both sampling times (February and July). The higher metals loads were associated with severe and various tissues alterations in contaminated crabs. We particularly noted in the gills a haemocytic infiltration, distension and enlargement of the lamellae, lifting of lamellar epithelium, necrotic lesions and fusion of lamellae in the most polluted sites (Menzel Bourguiba and Cimentery). Moreover, others pathological alterations were observed in digestive gland of crabs collected from polluted sites and with a severity site dependent. We observed necrotic tubules containing tissue debris in the lumen with more intensity in crabs collected from Cimentery site in both sampling times. The thickened basal laminae and the walling off of the tubules by haemocytes around the thickened basal laminae were more abundant at Menzel Bourguiba than at others sites. The coagulation in the thickened basal laminae was observed only at Cimentery in February. Tissues histopathological lesions were sensitive to discriminate crabs of different sites and demonstrated its usefulness in this biomonitoring study. We recommend the association of histopatholocial lesions to biochemical biomarkers in future biomonitoring studies.
Afficher plus [+] Moins [-]Sources and pathways of artificial radionuclides to soils at a High Arctic site
2014
Łokas, E. | Bartmiński, P. | Wachniew, P. | Mietelski, J. W. | Kawiak, T. | Środoń, J.
Activity concentrations, inventories and activity ratios of ¹³⁷Cs, ²³⁸Pu, ²³⁹ ⁺ ²⁴⁰Pu and ²⁴¹Am in soil profiles were surveyed in the dry tundra and the adjoining proglacial zones of glaciers at a High Arctic site on Svalbard. Vertical profiles of radionuclide activities were determined in up to 14-cm-thick soil sequences. Additionally, soil properties (pH, organic matter, texture, mineral composition and sorption capacity) were analyzed. Results obtained in this study revealed a large range of activity concentrations and inventories of the fallout radionuclides from the undetectable to the uncommonly high levels (inventories of 30,900 ± 940, 47 ± 6, 886 ± 80 and 296 ± 19 Bq/m² for ¹³⁷Cs, ²³⁸Pu, ²³⁹ ⁺ ²⁴⁰Pu and ²⁴¹Am, respectively) found in two profiles from the proglacial zone. Concentration of these initially airborne radionuclides in the proglacial zone soils is related to their accumulation in cryoconites that have a large ability to concentrate trace metals. The cryoconites develop on the surface of glaciers, and the material they accumulate is deposited on land surface after the glaciers retreat. The radionuclide inventories in the tundra soils, which effectively retain radionuclides due to high organic matter contents, were comparable to the global fallout deposition for this region of the world. The ²³⁸Pu/²³⁹ ⁺ ²⁴⁰Pu activity ratios for tundra soils suggested global fallout as the dominant source of Pu. The ²³⁸Pu/²³⁹ ⁺ ²⁴⁰Pu and ²³⁹ ⁺ ²⁴⁰Pu/¹³⁷Cs activity ratios in the proglacial soils pointed to possible contributions of these radionuclides from other, unidentified sources.
Afficher plus [+] Moins [-]Solar CPC pilot plant photocatalytic degradation of bisphenol A in waters and wastewaters using suspended and supported-TiO₂. Influence of photogenerated species
2014
Saggioro, Enrico Mendes | Oliveira, Anabela Sousa | Pavesi, Thelma | Tototzintle, Margarita Jiménez | Maldonado, Manuel Ignacio | Correia, Fábio Verissimo | Moreira, Josino Costa
Photocatalytic degradation of bisphenol A (BPA) in waters and wastewaters in the presence of titanium dioxide (TiO₂) was performed under different conditions. Suspensions of the TiO₂ were used to compare the degradation efficiency of BPA (20 mg L⁻¹) in batch and compound parabolic collector (CPC) reactors. A TiO₂ catalyst supported on glass spheres was prepared (sol–gel method) and used in a CPC solar pilot plant for the photodegradation of BPA (100 μg L⁻¹). The influence of OH·, O₂ ·⁻, and h ⁺ on the BPA degradation were evaluated. The radicals OH· and O₂ ·⁻ were proved to be the main species involved on BPA photodegradation. Total organic carbon (TOC) and carboxylic acids were determined to evaluate the BPA mineralization during the photodegradation process. Some toxicological effects of BPA and its photoproducts on Eisenia andrei earthworms were evaluated. The results show that the optimal concentration of suspended TiO₂ to degrade BPA in batch or CPC reactors was 0.1 g L⁻¹. According to biological tests, the BPA LC₅₀ in 24 h for E. andrei was of 1.7 × 10⁻² mg cm⁻². The photocatalytic degradation of BPA mediated by TiO₂ supported on glass spheres suffered strong influence of the water matrix. On real municipal wastewater treatment plant (MWWTP) secondary effluent, 30 % of BPA remains in solution; nevertheless, the method has the enormous advantage since it eliminates the need of catalyst removal step, reducing the cost of treatment.
Afficher plus [+] Moins [-]Saline irrigation and Zn amendment effect on Cd phytoavailability to Swiss chard (Beta vulgaris L.) grown on a long-term amended agricultural soil: a human risk assessment
2014
Valdez-González, J. C. | López-Chuken, U. J. | Guzmán-Mar, J. L. | Flores-Banda, F. | Hernández-Ramírez, A. | Hinojosa-Reyes, L.
Crops, particularly in the Northeast region of Mexico, have to cope with increasing soil salinization due to irrigation. Chloride (Cl⁻) concentration has been strongly related to enhance cadmium (Cd) uptake by plants due to increased solubility in the soil solution. The effect of irrigation with slightly saline water from a local well was evaluated in this work on the accumulation and translocation of Cd in Swiss chard (Beta vulgaris L.) grown in soil historically amended with stabilized sewage sludge under a regime of phosphorus and zinc fertilization. A factorial pot experiment was conducted with two phosphate fertilizer levels (PF, 0 and 80 kg ha⁻¹dry soil, respectively), two Zn levels (0 and 7 kg ha⁻¹dry soil), and two sources of water for irrigation deionized water (DW) and slightly saline well water (WW) from an agricultural site. Additionally, a human risk assessment for Cd ingestion from plants was assessed. Results showed that Cl⁻salinity in the WW effectively mobilized soil Cd and increased its phytoavailability. A higher level of Cd was found in roots (46.41 mg kg⁻¹) compared to shoots (10.75 mg kg⁻¹). Although the total content of Cd in the edible parts of the Swiss chard irrigated with WW exceeded permissible recommended consumption limit, bioavailable cadmium in the aboveground parts of the plant in relation to the total cadmium content was in the range from 8 to 32 %. Therefore, human health risks might be overestimated when the total concentration is taken into account.
Afficher plus [+] Moins [-]Source apportionment of surfactants in marine aerosols at different locations along the Malacca Straits
2014
Mustaffa, Nur Ili Hamizah | Latif, Mohd Talib | Ali, Masni Mohd | Khan, Md Firoz
This study aims to determine the source apportionment of surfactants in marine aerosols at two selected stations along the Malacca Straits. The aerosol samples were collected using a high volume sampler equipped with an impactor to separate coarse- and fine-mode aerosols. The concentrations of surfactants, as methylene blue active substance and disulphine blue active substance, were analysed using colorimetric method. Ion chromatography was employed to determine the ionic compositions. Principal component analysis combined with multiple linear regression was used to identify and quantify the sources of atmospheric surfactants. The results showed that the surfactants in tropical coastal environments are actively generated from natural and anthropogenic origins. Sea spray (generated from sea-surface microlayers) was found to be a major contributor to surfactants in both aerosol sizes. Meanwhile, the anthropogenic sources (motor vehicles/biomass burning) were predominant contributors to atmospheric surfactants in fine-mode aerosols.
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