خيارات البحث
النتائج 1321 - 1330 من 4,241
OSPAR standard method and software for statistical analysis of beach litter data
2017
Schulz, Marcus | van Loon, Willem | Fleet, David M. | Baggelaar, Paul | van der Meulen, Eit
The aim of this study is to develop standard statistical methods and software for the analysis of beach litter data. The optimal ensemble of statistical methods comprises the Mann-Kendall trend test, the Theil-Sen slope estimation, the Wilcoxon step trend test and basic descriptive statistics. The application of Litter Analyst, a tailor-made software for analysing the results of beach litter surveys, to OSPAR beach litter data from seven beaches bordering on the south-eastern North Sea, revealed 23 significant trends in the abundances of beach litter types for the period 2009–2014. Litter Analyst revealed a large variation in the abundance of litter types between beaches. To reduce the effects of spatial variation, trend analysis of beach litter data can most effectively be performed at the beach or national level. Spatial aggregation of beach litter data within a region is possible, but resulted in a considerable reduction in the number of significant trends.
اظهر المزيد [+] اقل [-]Isolation and characterization of PAH-degrading bacteria from the Eastern Province, Saudi Arabia
2017
Oyehan, Tajudeen A. | Al-Thukair, Assad A.
Contaminated sediment samples were collected from the Eastern Province, Saudi Arabia for isolation of pyrene- and phenanthrene-degrading bacteria by enrichment method. Four isolates were morphologically characterized as Gram-negative rod strains and 16S rRNA sequence analysis revealed the isolates as closely related to Pseudomonas aeruginosa, P. citronellolis, Ochrobactrum intermedium and Cupriavidus taiwanensis. Degradation of the polycyclic aromatic hydrocarbons (PAHs) by the latter three strains was investigated in liquid cultures. Results of concentration reduction analyzed with gas chromatography show that P. citronellolis_LB was efficient in removing phenanthrene, degrading 94% of 100ppm in 15days while O. intermedium_BC1 was more efficient in pyrene-removal, degrading 62% in 2weeks. Furthermore, bacterial growth assessment using optical density and population counts revealed the latter as more suitable for microbial growth analysis in PAH-containing cultures. In conclusion, the isolated bacterial strains could be further developed for efficient use in biodegradation of PAH.
اظهر المزيد [+] اقل [-]Spatial and temporal microbial pollution patterns in a tropical estuary during high and low river flow conditions
2017
Wiegner, T.N. | Edens, C.J. | Abaya, L.M. | Carlson, K.M. | Lyon-Colbert, A. | Molloy, S.L.
Spatial and temporal patterns of coastal microbial pollution are not well documented. Our study examined these patterns through measurements of fecal indicator bacteria (FIB), nutrients, and physiochemical parameters in Hilo Bay, Hawai'i, during high and low river flow. >40% of samples tested positive for the human-associated Bacteroides marker, with highest percentages near rivers. Other FIB were also higher near rivers, but only Clostridium perfringens concentrations were related to discharge. During storms, FIB concentrations were three times to an order of magnitude higher, and increased with decreasing salinity and water temperature, and increasing turbidity. These relationships and high spatial resolution data for these parameters were used to create Enterococcus spp. and C. perfringens maps that predicted exceedances with 64% and 95% accuracy, respectively. Mapping microbial pollution patterns and predicting exceedances is a valuable tool that can improve water quality monitoring and aid in visualizing FIB hotspots for management actions.
اظهر المزيد [+] اقل [-]Long-term changes in nutrients, chlorophyll a and their relationships in a semi-enclosed eutrophic ecosystem, Bohai Bay, China
2017
Qiao, Yinhuan | Feng, Jianfeng | Cui, Shangfa | Zhu, Lin
As the representative semi-enclosed bay of China, Bohai Bay has experienced severe eutrophication in recent decades. Monitoring data from 1995 to 2013 were analysed by generalized additive models (GAMs) to explore the temporal variations in nutrients concentrations, nutrient ratios, chlorophyll a (Chl a) concentrations and the responses of Chl a to the changes in nutrients in the spring and summer. The results showed that dissolved inorganic nitrogen (DIN) decreased from 1995 to 2000 but increased after 2000 in both the spring and summer, and soluble reactive phosphorus (SRP) decreased while the molar nitrogen/phosphorus (N/P) ratios (DIN to SRP) increased over the last two decades. Generally, P-limited phytoplankton growth was observed in the spring and summer and DIN was identified as the main pollutant constituent in Bohai Bay. Furthermore, negative correlations were found between DIN and Chl a in summer in Bohai Bay.
اظهر المزيد [+] اقل [-]Characterization of organic compounds in winter PM1 aerosols in a small industrial town
2017
Křůmal, K. | Mikuška, P. | Večeřa, Z.
PM1 aerosol, collected during winter campaign in urban area situated close to a large automobile factory, was analysed on content of selected organic compounds, namely monosaccharide anhydrides, diterpenoids (including retene and resin acids), n-alkanes (including pristane and phytane), polycyclic aromatic hydrocarbons (including picene), monosaccharides, disaccharides, polyols, hopanes and steranes.Monosaccharide anhydrides (MAs, markers for biomass burning) were the most abundant organic compounds (the mean sum of concentration of 513 ng m−3). The sum of MAs constituted in average 70.0% of the mass of all analysed organic compounds and 1.91% of the PM1 mass. Diterpenoids, markers for softwood combustion, were the second most abundant analysed organic compounds (the mean concentration of 119 ng m−3). The mean concentrations of other studied organic compounds were smaller, namely saccharides 31.6 ng m−3, n-alkanes, including isoprenoids 35.3 ng m−3, PAHs 15.6 ng m−3 and hopanes, including one sterane 1.54 ng m−3.Combustion of solid fuels (coal and wood) for household heating was the dominant emission source of carbonaceous aerosols sampled during the campaign. The composition of aerosols collected in the studied locality was affected by local emissions and also by regional transport of polluted air from small villages nearby Mladá Boleslav.Two unit risks (WHO and CalEPA) were applied for the estimation of carcinogenic risk of PAHs exposure. The computed lifetime cancer risk at the studied locality during the campaign period was 1.93 × 10−4 (WHO unit risk) and 2.43 × 10−6 (CalEPA unit risk) on average. However, the real cancer risk for the lifetime exposure (70 years) is lower at the studied locality because our measurement lasted only 2 weeks in winter when the concentrations of PAHs were higher than in other seasons of the year.
اظهر المزيد [+] اقل [-]Ocean acidification: One potential driver of phosphorus eutrophication
2017
Ge, Changzi | Chai, Yanchao | Wang, Haiqing | Kan, Manman
Harmful algal blooms which may be limited by phosphorus outbreak increases currently and ocean acidification worsens presently, which implies that ocean acidification might lead to phosphorus eutrophication. To verify the hypothesis, oxic sediments were exposed to seawater with different pH 30days. If pH was 8.1 and 7.7, the total phosphorus (TP) content in sediments was 1.52±0.50 and 1.29±0.40mg/g. The inorganic phosphorus (IP) content in sediments exposed to seawater with pH8.1 and 7.7 was 1.39±0.10 and 1.06±0.20mg/g, respectively. The exchangeable phosphorus (Ex-P) content in sediments was 4.40±0.45 and 2.82±0.15μg/g, if seawater pH was 8.1 and 7.7. Ex-P and IP contents in oxic sediments were reduced by ocean acidification significantly (p<5%). The reduced phosphorus in sediments diffused into water, which implied that ocean acidification was one potential facilitator of phosphorus eutrophication in oxic conditions.
اظهر المزيد [+] اقل [-]Tools for evaluating environmental performance at Brazilian public ports: Analysis and proposal
2017
Roos, Erica Caetano | Kliemann Neto, Francisco José
The port sector critically needs improved management techniques to evaluate its environmental performance. In the present study, we conducted an exploratory research to understand the metrics used in the Brazilian public ports to assess their environmental performance. We considered two state agencies and two port authorities of southern Brazil. As preliminary results, we found that economic factors are excluded in the tools for measuring environmental performance. A system of indicators to address this shortcoming was then proposed, but it could not be applied because of data deficiencies. Thus, the system was divided into two parts: a simplified system with 7 indicators (measuring costs related to criteria were measured only technically) and an advanced system with 5 indicators (approaching costs were currently difficult to measure). Thus, the proposed indicators can be applied by port authorities to facilitate decision-making related to environmental management. As suggestions for further work, we propose research that includes more ports, both public and private, to provide an overview at the national level.
اظهر المزيد [+] اقل [-]Coastal dynamics vs beach users attitudes and perceptions to enhance environmental conservation and management effectiveness
2017
Aretano, Roberta | Parlagreco, Luca | Semeraro, Teodoro | Zurlini, Giovanni | Petrosillo, Irene
This work carries out a landscape analysis for the last 60years to compare the degree of preservation of two areas on the same Italian coastline characterized by different environmental protection levels: a National designated protected areas and a highly tourist coastal destination. The conversion of natural land-covers into human land uses were detected for protected and unprotected coastal stretches highlighting that the only establishment of a protected area is not enough to stem undesirable land-use outcomes. A survey analysis was also conducted to assess attitudes of beach users and to evaluate their perception of natural habitats, beach and coastal water quality, and coastal dynamic over time. The results of 2071 questionnaires showed that there is similarity between subjective and objective data. However, several beach users perceived a bad quality of coastal water in the legally unprotected coastal area. The implications from a planning and management perspective are discussed.
اظهر المزيد [+] اقل [-]State of the art review and future directions in oil spill modeling
2017
Spaulding, Malcolm L.
A review of the state of the art in oil spill modeling, focused on the period from 2000 to present is provided. The review begins with an overview of the current structure of spill models and some lessons learned from model development and application and then provides guiding principles that govern the development of the current generation of spill models. A review of the basic structure of spill models, and new developments in specific transport and fate processes; including surface and subsurface transport, spreading, evaporation, dissolution, entrainment and oil droplet size distributions, emulsification, degradation, and sediment oil interaction are presented. The paper concludes with thoughts on future directions in the field with a primary focus on advancements in handling interactions between Lagrangian elements.
اظهر المزيد [+] اقل [-]Seasonal dynamics of marine litter along the Bulgarian Black Sea coast
2017
Simeonova, Anna | Chuturkova, Rozalina | Yaneva, Velika
In this study marine litter (ML) surveys were conducted in 8 beaches along the Bulgarian Black Sea coastline within 4 seasons for 2015–2016. The monitoring applied OSPAR guideline, classifying ML in eight categories and 167 types. The results exhibited predominance of artificial polymer materials - 84.3%. ML densities ranged from 0.0587±0.005 to 0.1343±0.008 n/m2, highest on the urban beaches. The seasonal dynamics of most top 10 ML showed highest quantities in summer than the other seasons, as the differences are of high statistical significance (0.001≤P≤0.05). Top 1 ML item for most of the beaches was cigarette butts and filters reaching 1008±10.58 nos. in summer and from 19±3.41 to 89±7.81 nos. during the rest of the seasons (P<0.001). For the pronounced seasonality contributed the recreational activities, increased tourist flow and the wild camping. The investigation will enrich data scarcity for Descriptor 10 “Marine litter”.
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