خيارات البحث
النتائج 611 - 620 من 3,243
Pb, Cu and Cd distribution in five estuary systems of Marche, central Italy
2015
Annibaldi, Anna | Illuminati, Silvia | Truzzi, Cristina | Libani, Giulia | Scarponi, Giuseppe
Heavy metals are subjected to monitoring in estuarine and marine water by the European Union Water Framework Directive, which requires water body health to be achieved by 2021. This is the first survey of heavy metals content in five estuaries of Marche, a region in central Italy. Results showed that total Pb and Cu concentrations decreased by 70–80%, from 1000–2000 to 100–200ngL−1 (Pb) and from 2000–3000 to 500–1000ngL−1 (Cu) from river to sea. Cd was consistently 20–40ngL−1. Dissolved Pb and Cu concentrations declined by 50% and 70% respectively passing from oligohaline to euhaline water, from 150 to 70ngL−1 and from 2000–1000 to 600–400ngL−1. Cd decreased slightly from ∼20 to ∼10ngL−1. Although such concentrations are in the range allowed by the Water Framework Directive, they far exceed (up to 10×) the ground content ceiling set for 2021.
اظهر المزيد [+] اقل [-]Methods for Treatment of Animal Manures to Reduce Nutrient Pollution Prior to Soil Application
2015
Szogi, Ariel A. | Vanotti, Matias B. | Ro, Kyoung S.
For centuries, animal manures have been a traditional source of nutrients in agriculture. However, disposal of animal manure has become an environmental problem in recent times as a result of increased concentration of animal production within small geographic areas. Manure nitrogen (N) and phosphorus (P) applied in excess of the assimilative soil capacity have the potential to reach and pollute water resources through soil leaching or runoff. Yet, conservation and recovery of N and P is a concern in modern agriculture because of the high cost and future limited supply of commercial fertilizers, particularly P which is extracted from mineral deposits. Therefore, N and P recovery methods are necessary to reduce their excess prior to manure soil application and recover them as valuable products. This article is a review of existing technologies for animal waste treatment and additional new methods for recycling manure N and P and possible recovery as valuable byproducts.
اظهر المزيد [+] اقل [-]Relationship of MISR component AODs with black carbon and other ground monitored particulate matter composition
2015
Zeeshan, Muhammad | Nguyễn, Thị Kim Oanh
This study assessed the relationship between the satellite Aerosol Optical Depths (AODs) and the ground monitored concentrations of particulate matter (PM) mass and its major constituents (black carbon–BC, organic carbon–OC, sulfates and nitrates), respectively. Both component AOD and total AOD products of Multi–angel Imaging Spectro Radiometer (MISR) were used for comparison along with the AOD product of the Moderate Resolution Imaging Spectroradiometer (MODIS). The ground PM data available during the period from 2004 to 2010 at the Asian Institute of Technology (AIT), a suburb site of the Bangkok Metropolitan Region, was used. MODIS and MISR AODs were validated against Sun photometer AOD, monitored at the Pimai AERONET station which showed strong linear regression with high R2 values of 0.87 and 0.92, respectively. The correlation coefficients between MODIS and MISR AODs and PM mass concentrations, respectively, were improved after exclusion of observations with cloud cover above 3/10. The R values (square root of determination coefficient R2) for linear relationships between PM10 and MODIS AOD were accordingly increased from 0.33 to 0.58 for MODIS AOD and from 0.25 to 0.54 for MISR AOD, while those for PM2.5 were improved from 0.30 to 0.55 for MODIS AOD and from 0.31 to 0.43 for MISR AOD. The stepwise regression was conducted to analyze the relationship between MISR component AODs and the mass concentration of PM10 and PM2.5, respectively, as well as their constituents. Higher R values were obtained for all regression equations using MISR component AODs as compared to those using total AOD. MISR component AODs showed higher capacity for monitoring daily BC (R=0.74–0.75) and sulfates (R=0.72), as compared to nitrates (R=0.52–0.54) and hourly OC (R=0.47). The potential of MISR component AODs for ambient PM monitoring should be explored and applied in other regions.
اظهر المزيد [+] اقل [-]Number of bacteria decomposing organic phosphorus compounds and phosphatase activity in the sand of two marine beaches differing in the level of anthropopressure
2015
Mudryk, Z.J. | Perliński, P. | Antonowicz, J. | Robak, D.
Number of heterotrophic bacteria ability to decompose organic phosphorus compounds and the level of phosphatase activity in the sand of two marine beaches (southern coast of the Baltic Sea) differing in the level of anthropopressure were studied. The study showed that the number of bacteria and level phosphatase activity were higher in the sand of the beach subjected to stronger anthropopressure. In both studied beaches bacteria hydrolysing DNA were the most numerous (92.7–302.8CFU·g−1 d.w.). The least numerous were phytin (26.0·103CFU·g−1 d.w.) and phenolphthalein diphosphate (11.1·103CFU·g−1 d.w.) decomposing bacteria. Number of bacteria able to attack tested organic phosphorus compounds were the most numerous in dry zones (10.77–739.92CFU·g−1 d.w.) then wet zones (3.34–218.15CFU·g−1 d.w.). In both studied beaches bacteria hydrolysing organic phosphorus compounds and phosphatase activity generally were more numerous in surface sand layer. Seasonal variation in the occurrence of bacteria in both studied beaches was observed.
اظهر المزيد [+] اقل [-]Laboratory tests for the phytoextraction of heavy metals from polluted harbor sediments using aquatic plants
2015
Mânzatu, Carmen | Nagy, Boldizsár | Ceccarini, Alessio | Iannelli, Renato | Giannarelli, Stefania | Majdik, Cornelia
The aim of this study was to investigate the concentrations and pollution levels of heavy metals, organochlorine pesticides, and polycyclic aromatic hydrocarbons in marine sediments from the Leghorn Harbor (Italy) on the Mediterranean Sea. The phytoextraction capacity of three aquatic plants Salvinia natans, Vallisneria spiralis, and Cabomba aquatica was also tested in the removal of lead and copper, present in high concentration in these sediments. The average detectable concentrations of metals accumulated by the plants in the studied area were as follows: >3.328±0.032mg/kg dry weight (DW) of Pb and 2.641±0.014mg/kg DW of Cu for S. natans, >3.107±0.034g/kg DW for V. spiralis, and >2.400±0.029mg/kg DW for C. aquatica. The occurrence of pesticides was also analyzed in the sediment sample by gas chromatography coupled with mass spectrometry (GC/MS).Due to its metal and organic compound accumulation patterns, S. natans is a potential candidate in phytoextraction strategies.
اظهر المزيد [+] اقل [-]The air quality of Beijing–Tianjin–Hebei regions around the Asia-Pacific Economic Cooperation (APEC) meetings
2015
Sheng, Li | Lu, Gai | Ma, Xin | Hu, Jiang-kai | Song, Zhen-xin | Huang, Shun-xiang | Zhang, Ji-ping
The Asia-Pacific Economic Cooperation (APEC) meetings of 2014 were held from November 7–12. In order to guarantee the good air quality of Beijing, the Chinese government has taken the most stringent emission reduction measures to date. This study analyzed and compared the air quality of Beijing–Tianjin–Hebei (BTH) regions just before and after APEC meetings. The observations show that the APEC emission reduction measures have effectively improved the air quality of BTH, especially Beijing. Compared with normal emission period (NEP), the PM2.5, PM10, O3, SO2, NO2 and CO concentrations of Beijing during emission reduction periods were reduced by about 58%, 49%, 9%, 34%, 23%, and 4%. The air quality in Tianjin and Hebei were improved significantly, but the rises were smaller than ones in Beijing. During the APEC meetings, due to the weak southerly wind the contribution of backward trajectories from the neighboring air pollution areas of Beijing was less than 10%. The stringent emission reduction measures and favorable weather conditions ensured the good air qualities during the APEC meetings.
اظهر المزيد [+] اقل [-]Trace element and stable isotope analysis of fourteen species of marine invertebrates from the Bay of Fundy, Canada
2015
English, Matthew D. | Robertson, Gregory J. | Mallory, Mark L.
The Bay of Fundy, Canada, is a macrotidal bay with a highly productive intertidal zone, hosting a large abundance and diversity of marine invertebrates. We analysed trace element concentrations and stable isotopic values of δ15N and δ13C in 14 species of benthic marine invertebrates from the Bay of Fundy's intertidal zone to investigate bioaccumulation or biodilution of trace elements in the lower level of this marine food web. Barnacles (Balanus balanus) consistently had significantly greater concentrations of trace elements compared to the other species studied, but otherwise we found low concentrations of non-essential trace elements. In the range of trophic levels that we studied, we found limited evidence of bioaccumulation or biodilution of trace elements across species, likely due to the species examined occupying similar trophic levels in different food chains.
اظهر المزيد [+] اقل [-]Spatial variation, fractionation and sedimentary records of mercury in the East China Sea
2015
Duan, Li-Qin | Song, Jin-Ming | Yu, Yu | Yuan, Hua-Mao | Li, Xue-Gang | Li, Ning
Surface and core sediments were collected to study distributions, phases and potential environmental risk of Hg and to reconstruct anthropogenic Hg change over the past one hundred years in the East China Sea (ECS). Hg contents in surface sediments displayed a decreasing gradient from the Changjiang Estuary to the outer sea. Sequential extraction analysis showed that Hg mainly existed as residual fraction (70.18% of total), and while organic matter fraction (22.96% of total) was the main component of labile fraction, indicating the strong adsorption of organic matters on Hg. Enrichment factor and sediment quality guidelines suggested that Hg in sediments of ECS were at minor enrichment and low adverse effect. Temporal distributions of total Hg content, labile fraction, burial flux and anthropogenic Hg flux showed that anthropogenic Hg input increased since the 1960s, which was related to riverine input and atmospheric transport.
اظهر المزيد [+] اقل [-]Assessing the viability of microorganisms in the ballast water of vessels transiting the North Atlantic Ocean
2015
Steichen, Jamie L. | Quigg, Antonietta
Testing phytoplankton viability within ballast tanks and receiving waters of ballast water discharge remain understudied. Potentially harmful dinoflagellates and diatoms are transported via ballast water to Galveston Bay, Texas (USA), home to three major ports: Houston, Texas City and Galveston. Ballast water from vessels transiting the North Atlantic Ocean was inoculated into treatments representing low and high salinity conditions similar to the Ports of Houston and Galveston respectively. Phytoplankton in ballast water growout experiments were deemed viable and showed growth in low and mid salinities with nutrient enrichment. Molecular methods identified several genera: Dinophysis, Gymnodinium, Gyrodinium, Heterocapsa, Peridinium, Scrippsiella, Chaetoceros and Nitzschia. These phytoplankton genera were previously identified in Galveston Bay except Scrippsiella. Phytoplankton, including those capable of forming harmful algal blooms leading to fish and shellfish kills, are transported to Galveston Bay via ballast water, and are viable when introduced to similar salinity conditions found in Galveston Bay ports.
اظهر المزيد [+] اقل [-]Oil spill experiment using airborne DLR ESAR off the coast of Diu, India
2015
Sasamal, S.K. | Rao, M.V.
Oil spill experiment results in the coastal waters of Diu, India, with an airborne DLR ESAR sensor are discussed with reference to the SAR frequency, polarization and viewing angle. The SAR data acquired in the quad polarization of the L band and dual polarization of the C band over two spills are studied. A higher oil and water contrast is observed in the L-VV polarization than in the C-HH mode. Oil spill discrimination is possible over a wider view angle of the airborne SAR sensor data in L band than in C band. This study has also analyzed the spread and drift of oil in coastal waters.
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