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Результаты 1511-1520 из 4,033
Algicidal and denitrification characterization of Acinetobacter sp. J25 against Microcystis aeruginosa and microbial community in eutrophic landscape water
2016
Su, Jun feng | Ma, Min | Wei, Li | Ma, Fang | Lu, Jin suo | Shao, Si cheng
Acinetobacter sp. J25 exhibited good denitrification and high algicidal activity against toxic Microcystis aeruginosa. Response surface methodology (RSM) experiments showed that the maximum algicidal ratio occurred under the following conditions: temperature, 30.46°C; M. aeruginosa density, 960,000cellsmL−1; and inoculum, 23.75% (v/v). Of these, inoculum produced the maximum effect. In the eutrophic landscape water experiment, 10% bacterial culture was infected with M. aeruginosa cells in the landscape water. After 24days, the removal ratios of nitrate and chlorophyll-a were high, 100% and 87.86%, respectively. The denitrification rate was approximately 0.118mgNO3−–N·L−1·h−1. Moreover, the high-throughput sequencing result showed that Acinetobacter sp. J25 was obviously beneficial for chlorophyll-a and nitrate removal performance in the eutrophic landscape water treatment. Therefore, strain J25 is promising for the simultaneous removal of chlorophyll-a and nitrate in the eutrophic landscape water treatment.
Показать больше [+] Меньше [-]Distribution and quantity of microplastic on sandy beaches along the northern coast of Taiwan
2016
Kunz, Alexander | Walther, Bruno A. | Löwemark, Ludvig | Lee, Yao-Chang
Plastic pollution is now ubiquitous in the world's oceans, and studies have shown macroplastic and microplastic pollution of beaches in several East Asian countries. However, to our knowledge, no study of microplastic pollution has been conducted in Taiwan yet. Therefore, we collected sand samples from four beaches along the northern coast of Taiwan in 2015 and extracted microplastic particles using a saturated NaCl solution. Microplastic particles were identified using synchrotron-based FTIR spectroscopy. We recovered 4 to 532 particles from eight 0.0125m3 samples, with a total of 1097 particles weighing 0.771g. A negative trend between the size of the particles and their numbers was documented. We thus established that microplastic pollution was ubiquitous along Taiwan's northern coast. Future research should more comprehensively sample beaches around the entirety of Taiwan's coast, and special emphasis should be placed on identifying different sources and movements of microplastic.
Показать больше [+] Меньше [-]Turbulent transport of particle-bound PAHs: A feasibility study combining GC-APLI-MS and eddy covariance
2016
Stader, Christian | Deventer, Malte Julian | Klemm, Otto | Achten, Christine
A novel approach combining gas chromatography-atmospheric pressure laser ionization-time-of-flight-mass spectrometry (GC-APLI-MS) with the micrometeorological eddy covariance (EC) technique is demonstrated to quantify particle-bound polycyclic aromatic hydrocarbons (PAH) mass fluxes above a central European city. During the case study, 18 different PAH compounds could be identified in two one-hour particle samples and, in combination with size-resolved particle deposition velocities obtained from EC measurements, inferred particulate PAH mass fluxes for two respective size fractions (0.060–0.108 μm and 0.170–10 μm) were quantified. Maximum concentrations and fluxes (in the order of 0.9 ± 0.09–17 ± 8 ng m−2 hr−1) were estimated for the 5-ring PAHs benzo[e]pyrene, benzo[a]pyrene and perylene. Fingerprints of PAH concentrations suggest strong pyrogenic sources, particularly wood burning.
Показать больше [+] Меньше [-]Bioremediation of the Exxon Valdez oil in Prince William Sound beaches
2016
Boufadel, Michel C. | Geng, Xiaolong | Short, Jeff
Oil from the Exxon Valdez laden with polycyclic aromatic hydrocarbons (PAH) has persisted on some beaches in Prince William Sound, Alaska, >20years after these beaches became contaminated. The degradation rate of the total PAH (TPAH) is estimated at 1% per year. Low oxygen concentrations were found to be the major factor causing oil persistence, and bioremediation through the injection of hydrogen peroxide and nutrients deep into four beaches in PWS were conducted in the summers of 2011 and 2012. It was found that due to the treatment, the TPAH biodegradation rate was between 13% and 70% during summer 2011 and summer 2012. The results also showed high efficiency in the delivery of oxygen and nutrient to the contaminated areas of the beach. However, the approach has an environmental cost associated with it, and stakeholders would need to conduct a rigorous net environmental benefit analysis (NEBA) for pursuing the bioremediation of submerged contaminated sediments, especially in higher latitudes.
Показать больше [+] Меньше [-]Polycyclic aromatic hydrocarbons in surface sediments from the Coast of Weihai, China: Spatial distribution, sources and ecotoxicological risks
2016
Zhang, Daolai | Liu, Jinqing | Yin, Ping | Lin, Xuehui | Liu, Na | Meng, Xianwei
This study was conducted to measure the polycyclic aromatic hydrocarbon (PAH) concentrations and evaluate the distribution, sources in surface sediments from various coastal sites in Weihai, which create good conditions for rapid development because of their excellent geographical location and abundant marine resources. The results indicated that the total PAHs contents in the sediments of Weihai ranged from 2.69 to 166.50ngg−1, with an average of 67.44ngg−1. Phenanthrene, Fluoranthene, Benzo(b)fluoranthene, Chrysene, and Pyrene were dominant in sediments, primarily as a result of high temperature combustion and biomass. Molecular ratios suggested that these PAHs in the sediments of Weihai were predominantly from pyrogenic sources such as grass, wood and charcoal combustion, as well as engine exhaust which is similar to the result of the study of the Yellow River Delta, China. The result of probability risk assessment additionally elucidated low PAH ecological risk in the surface sediments of Weihai, China.
Показать больше [+] Меньше [-]Geochemical speciation and ecological risk assessment of selected metals in the surface sediments of the northern Persian Gulf
2016
Neyestani, Mahmoud Reza | Bastami, Kazem Darvish | Esmaeilzadeh, Marjan | Shemirani, Farzaneh | Khazaali, Aida | Molamohyeddin, Neda | Afkhami, Majid | Nourbakhsh, Shahram | Dehghani, Mohsen | Aghaei, Sina | Firouzbakht, Mohammad
The present study aimed to geochemical speciation of metals in the surface sediments of the northern Persian Gulf. Metal contents in the sediment were observed in the order: Al>Fe>Cr>Ni>V>Zn>Cu>Co>As>Pb>Cd. The results of sequential extraction procedure revealed that all metals were predominantly associated with the residual fraction. Among the metals, Cu and As exhibited higher bioavailability. The risk assessment code (RAC) indicated that Cu, As and Cd had medium environmental risk at some sampling sites. Based on enrichment factor (EF), Cd and As had moderate to significant enrichment.
Показать больше [+] Меньше [-]Environmental genotoxicity assessment along the transport routes of chemical munitions leading to the dumping areas in the Baltic Sea
2016
Baršienė, Janina | Butrimavičienė, Laura | Grygiel, Włodzimierz | Stunžėnas, Virmantas | Valskienė, Roberta | Greiciūnaitė, Janina | Stankevičiūtė, Milda
The frequencies of micronuclei (MN), nuclear buds (NB) and nuclear buds on filament (NBf) were examined in 660 specimens of herring (Clupea harengus) collected in 2009–2014 at 65 study stations located mainly along the chemical munition transport routes in the Baltic Sea. The frequency of nuclear abnormalities was strongly increased in herring caught at four stations located close to chemical munition dumping sites, or CWAs — substances (chemical warfare agents) in sediments. Significant increase of MN, NB and NBf was observed in fish caught November 2010–2013 compared to 2009. The most significantly increased genotoxicity responses were recorded in fish caught at stations along CW (chemical weapons) transport routes, close to the Bornholm CW dumping area, in zones with CWAs in sediments and with oil–gas platforms.
Показать больше [+] Меньше [-]Parallel measurements of organic and elemental carbon dry (PM1, PM2.5) and wet (rain, snow, mixed) deposition into the Baltic Sea
2016
Witkowska, Agnieszka | Lewandowska, Anita | Falkowska, Lucyna M.
Parallel studies on organic and elemental carbon in PM1 and PM2.5 aerosols and in wet deposition in various forms of its occurrence were conducted in the urbanised coastal zone of the Baltic Sea. The carbon load introduced into the sea water was mainly affected by the form of precipitation. Dry deposition load of carbon was on average a few orders of magnitude smaller than wet deposition. The suspended organic carbon was more effectively removed from the air with rain than snow, while an inverse relationship was found for elemental carbon. However the highest flux of water insoluble organic carbon was recorded in precipitation of a mixed nature. The atmospheric cleaning of highly dissolved organic carbon was observed to be the most effective on the first day of precipitation, while the hydrophobic elemental carbon was removed more efficiently when the precipitation lasted longer than a day.
Показать больше [+] Меньше [-]Assessment of natural radioactivity and 137Cs in some coastal areas of the Saudi Arabian gulf
2016
Al-Ghamdi, H. | Al-Muqrin, A. | El-Sharkawy, A.
The levels of natural radioactivity have been investigated in some Saudi Arabian Gulf coastal areas. Sampling sites were chosen according to the presence of nearby non-nuclear industrial activities such as, the two main water desalination plants in Al Khobar and Al Jubail, and Maaden phosphate complex in Ras Al Khair, to ensure that effluents discharges into the Arabian Gulf didn't enhance radioactivity in seawater and shore sediments. Seawater samples were analyzed for radium isotopes (Ra-226 & Ra-228) and measured by gamma spectrometry using high purity germanium detector, after radiochemical separation of the isotopes by co-precipitation with MnO2. Shore sediment samples were analyzed for 226Ra, 228Ra (232Th), 4°K and 137Cs using gamma sepectrometry. A small variation was observed in the activity concentrations of the investigated radioisotopes, and the activity levels were comparable to those reported in literature. Quality assurance and methods validation were established through the efficiency calibration of the detectors, the estimation of uncertainties, the use of blanks, the analysis of standard reference materials and the intercomparison and proficiency tests. Radiological hazards were assessed, and the annual effective dose had an average value of 0.02mSv. On the basis of the current results, we may conclude that any radiological hazards to the public visiting these shores are not expected.
Показать больше [+] Меньше [-]Seasonal hypoxia regulates macrobenthic function and structure in the Mississippi Bight
2016
Rakocinski, Chet F. | Menke, Daneen P.
Hypoxic conditions are escalating to the east of the Mississippi River within the Mississippi Bight. The objective of this study was to examine changes in macrobenthic function and structure relative to seasonal hypoxia over a 3.5year period at the 10m (Site 6) and 20m (Site 8) isobaths within the Mississippi Bight. Seasonal hypoxia acted as a regular periodic disturbance during the study period, although the magnitude and duration of hypoxia varied inter-annually. Macrobenthic metrics revealed seasonal hypoxia effects on secondary production potential and community maturity, which agrees with previous studies. In addition, metrics were notably higher at the 20m isobath during the latter half of the study period, following the Deepwater Horizon (DwH) oil spill. This study confirms hypoxia as a major driver affecting the function and structure of soft-bottom macrobenthos in the Mississippi Bight.
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