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Investigating the impact on modeled ozone concentrations using meteorological fields from WRF with an updated four–dimensional data assimilation approach
2015
Godowitch, James M. | Gilliam, Robert C. | Roselle, Shawn J.
The four–dimensional data assimilation (FDDA) technique in the Weather Research and Forecasting (WRF) meteorological model has recently undergone an important update from the original version. Previous evaluation results have demonstrated that the updated FDDA approach in WRF provides more accurate wind fields aloft than the original approach, particularly during the nocturnal period when low level jets are a common feature in the Eastern United States. Due to the importance of WRF/FDDA meteorological fields in retrospective air quality applications, a modeling study with the Community Multiscale Air Quality (CMAQ) model was undertaken to ascertain if the improved wind flow fields translate into better performance for ozone. To undertake this objective, separate CMAQ model simulations were performed with meteorological inputs generated by WRF using the original and the updated FDDA approaches for a three month summer period. The evaluation effort focused on observed and modeled surface ozone from a mid–morning hour (10 local daylight time (LDT)). Comparisons of modeled results against concentrations aloft from an instrumented tall tower and from available morning vertical profile measurements were also examined. Surface concentrations near 10 LDT are desirable for evaluating the transport process since they are often representative of ozone that has been transported aloft overnight and has undergone downward entrainment in response to convective mixing the following morning. Statistical results from surface observed and modeled concentration pairs indicated modeled ozone from the CMAQ simulation using the updated FDDA meteorology displayed smaller biases and lower absolute errors at 88% and 80% of monitoring sites, respectively, in the Eastern United States. The CMAQ results with the updated FDDA generally exhibited smaller biases and lower absolute errors at monitoring sites across the northern states than in the southeastern states. The results provide evidence that the more accurate wind flows generated with the updated WRF/FDDA approach improved CMAQ model performance based on the statistical results from 10 LDT ozone concentrations.
Show more [+] Less [-]The New York Bight 25years later: Use impairments and policy challenges
2015
Ofiara, Douglas D.
This paper reexamines policies and outcomes concerning the NY Bight Restoration Plan, and the NY–NJ Harbor Estuary Program (NYNJHEP) precipitated by washups of marine debris and medical wastes in the New York Bight some 25-years ago. Findings indicate progress has been made but further work is necessary. Extensive beach closures have not occurred since 1987–88, although localized closings occur annually from pathogens. Objectives of “0” beach closures may not be feasible for some beaches, not to exceed 5% closures may be more achievable. Pathogen and DO data show further reductions of the last 10–20% will be more challenging and costly, suggesting “hot spots” be a focus for further remediation. Marine debris show increasing trends on beaches; presence of balloons, plastic bags, syringes and personal hygiene items found annually is another concern. Future challenges are on two fronts, upstream (harbor estuary based)-toxics, nutrient/organic loads, and atmospheric (bight based)-toxics, metals.
Show more [+] Less [-]Temporal pattern in biometrics and nutrient stoichiometry of the intertidal seagrass Zostera japonica and its adaptation to air exposure in a temperate marine lagoon (China): Implications for restoration and management
2015
Zhang, Xiaomei | Zhou, Yi | Liu, Peng | Wang, Feng | Liu, Bingjian | Liu, Xujia | Yang, Hongsheng
In coastal areas of China, the seagrass Zostera japonica has drastically decreased in the past decades. Swan Lake is an exception, where we found extensive areas of Z. japonica beds. The growth of Z. japonica in the lagoon exhibited strong seasonal variation. The maximum shoot density of 9880±2786shootsm−2 occurred in August. The maximum specific growth rate (SGR) of 4.99±1.99%⋅d−1 was recorded in June 2012. SGR might be a good parameter for assessing the growth status of Z. japonica population. N and P contents in the rhizome were significantly lower than those in the leaf and leaf sheath. Lower C/P ratios suggested P enrichment of the seagrass. The occurrence of Z. japonica in Swan Lake was featured by adapting to the intertidal harsh environments. The transplantation method using sectioned rhizomes would be a potential way for restoration of degraded Z. japonica beds. The establishment of the Rongcheng Swan National Nature Reserve in China has contributed to the survival and expansion of Z. japonica in Swan Lake.
Show more [+] Less [-]Effect of heavy metals on the carbon and nitrogen ratio in Avicennia marina from polluted and unpolluted regions
2015
Yadav, Ajay | Ram, Anirudh | Majithiya, Divya | Salvi, Shailesh | Sonavane, Swati | Kamble, Archana | Ghadigaonkar, Suman | Jaiswar, Jiyalal Ram M. | Gajbhiye, S.N.
The accumulation of heavy metals and its impact on the C/N ratio of Avicennia marina of the Patalganga and Amba estuaries were studied. Vadinar was selected as a relatively uncontaminated location for comparison. Cd was accumulated in leaves of the Patalganga and Amba estuarine mangroves; however, at Vadinar it was accumulated and arrested only in roots and stems. Negative correlation of Cr, Cd, Pb and Zn with C in the mangroves suggested that their accumulation may lead to lowered C content in the mangroves. The average C/N ratios in mangroves of the inner Patalganga estuary, Patalganga mouth, and Amba estuary were found to be 80.1±7.3, 105.8±12.5 and 52.4±3.4 respectively, whereas at Vadinar it was well within the expected range (26.4±2.8). The results of the present study suggest: (i) metal accumulation, leading to less carbon content in plants; (ii) heavy metal enrichment in the root zone sediment, affecting the uptake of nitrogen by plants and resulting in altered C/N ratio.
Show more [+] Less [-]Trace elements pollution and toxicity of airborne PM10 in a coal industrial city
2015
Xiaoyan, Song | Longyi, Shao | Shushen, Yang | Riying, Song | Limei, Sun | Shihong, Cen
Trace elements in particulate matter associated with coal industries hold high risk to human health. Understanding the contents and occurrences of modes of these elements as well as their contribution to particulate toxicity is significant both environmentally and pathologically. A total of 24 PM10 samples were collected in Pingdingshan City, a coal industrial city in North China, in both winter and summer of 2008. An inductively coupled plasma mass spectrometry (ICP–MS) was used to determine the concentrations of 12 trace elements associated with coal industries (Cr, Ni, Cu, Zn, As, Mo, Cd, Sn, Sb, Tl, Pb, and Bi) in PM10 samples. The results indicated that the trace element concentrations were higher in winter than in summer; due mainly to more coal combustion during winter and to the different meteorological conditions of these two seasons. The soluble proportions of these trace elements compared with total values of intact whole samples were higher in winter than in summer, and this difference was attributed mainly to more SO2 reacting with pre–existing particles to form soluble particles in winter. Of all the analyzed elements, Ni, Tl, Sb, Mo, and Cd occurred mainly in the soluble state (>50% in the soluble fraction), Cr, Cu, Zn, and As occurred in both the soluble and insoluble state (20% to 50% in the soluble fraction), and Sn, Pb, and Bi occurred mainly in the insoluble state (<20% in the soluble fraction). A plasmid DNA assay indicated that winter samples had higher toxicity than summer samples. The correlation of PM10 toxicity (TD50 value) with the contribution of various trace elements to DNA damage (trace element concentration) was further analyzed, and the results indicated that PM10 toxicity was caused mainly by the soluble fractions of trace elements, including those of Ni, Pb, Cu, Cd, As, Zn, Cr, and Tl, which were the major toxic trace elements in Pingdingshan PM10.
Show more [+] Less [-]Studies on crude oil removal from pebbles by the application of biodiesel
2015
Oil residues along shorelines are hard to remove after an oil spill. The effect of biodiesel to eliminate crude oil from pebbles alone and in combination with petroleum degrading bacteria was investigated in simulated systems. Adding biodiesel made oil detach from pebbles and formed oil–biodiesel mixtures, most of which remained on top of seawater. The total petroleum hydrocarbon (TPH) removal efficiency increased with biodiesel quantities but the magnitude of augment decreased gradually. When used with petroleum degrading bacteria, the addition of biodiesel (BD), nutrients (NUT) and BD+NUT increased the dehydrogenase activity and decreased the biodegradation half lives. When BD and NUT were replenished at the same time, the TPH removal efficiency was 7.4% higher compared to the total improvement of efficiency when BD and NUT was added separately, indicating an additive effect of biodiesel and nutrients on oil biodegradation.
Show more [+] Less [-]Marine debris ingestion by albatrosses in the southwest Atlantic Ocean
2015
Jiménez, Sebastián | Domingo, Andrés | Brazeiro, Alejandro | Defeo, Omar | Phillips, Richard A.
Plastics and other marine debris affect wildlife through entanglement and by ingestion. We assessed the ingestion of marine debris by seven albatross species in the southwest Atlantic by analyzing stomach contents of birds killed in fisheries. Of the 128 specimens examined, including four Diomedea species (n=78) and three Thalassarche species (n=50), 21 (16.4%) contained 1–4 debris items, mainly in the ventriculus. The most common type was plastic fragments. Debris was most frequent in Diomedea species (25.6%) and, particularly, Diomedea sanfordi (38.9%) and very rare in Thalassarche species (2.0%), presumably reflecting differences in foraging behavior or distribution. Frequency of occurrence was significantly higher in male than female Diomedea albatrosses (39.3% vs. 18.0%). Although levels of accumulated debris were relatively low overall, and unlikely to result in gut blockage, associated toxins might nevertheless represent a health risk for Diomedea albatrosses, compounding the negative impact of other human activities on these threatened species.
Show more [+] Less [-]Recovery from TBT pollution in English Channel environments: A problem solved?
2015
Langston, W.J. | Pope, N.D. | Davey, M. | Langston, K.M. | O’ Hara, S.C.M. | Gibbs, P.E. | Pascoe, P.L.
Following recognition of effects in the 1980s, tributyltin (TBT) has been monitored at sites in the English Channel to evaluate the prognosis for biota – spanning the introduction of restrictions on TBT use on small boats and the recent phase-out on the global fleet. We describe how persistence and impact of TBT in clams Scrobicularia plana has changed during this period in Southampton Water and Poole Harbour. TBT contamination (and loss) in water, sediment and clams reflects the abundance and type of vessel activity: half-times in sediment (up to 8y in Poole, 33y in Southampton) are longest near commercial shipping. Recovery of clam populations – slowest in TBT-contaminated deposits – provides a useful biological measure of legislative efficacy in estuaries. On rocky shores, recovery from imposex in Nucella lapillus is evident at many sites but, near ports, is prolonged by shipping impacts, including sediment legacy, for example, in the Fal.
Show more [+] Less [-]Modeling increased riverine nitrogen export: Source tracking and integrated watershed-coast management
2015
Yu, Dan | Yan, Weijin | Chen, Nengwang | Peng, Benrong | Hong, Huasheng | Zhuo, Guihua
The global NEWS model was calibrated and then used to quantify the long term trend of dissolved inorganic nitrogen (DIN) export from two tributaries of Jiulong River (SE China). Anthropogenic N inputs contributed 61–92% of river DIN yield which increased from 337 in 1980s to 1662kgNkm−2yr−1 in 2000s for the North River, and from 653 to 3097kgNkm−2yr−1 for the West River. North River and West River contributed 55% and 45% respectively of DIN loading to the estuary. Rapid development and poor management driven by national policies were responsible for increasing riverine N export. Scenario analysis and source tracking suggest that reductions of anthropogenic N inputs of at least 30% in the North River (emphasis on fertilizer and manure) and 50% in the West River (emphasis on fertilizer) could significantly improve water quality and mitigate eutrophication in both river and coastal waters.
Show more [+] Less [-]Baseline distribution and sources of linear alkyl benzenes (LABs) in surface sediments from Brunei Bay, Brunei
2015
Alkhadher, Sadeq Abullah Abdo | Zakaria, Mohamad Pauzi | Fatimah Md. Yusoff, | Kannan, Narayanan | Suratman, Suhaimi | Keshavarzifard, Mehrzad | Magam, Sami Muhsen | Masood, Najat | Vaezzadeh, Vahab | Sani, Muhamad Shirwan Abdullah
Sewage pollution is one of major concerns of coastal and shoreline settlements in Southeast Asia, especially Brunei. The distribution and sources of LABs as sewage molecular markers were evaluated in surface sediments collected from Brunei Bay. The samples were extracted, fractionated and analyzed using gas chromatography- mass spectrometry (GC-MS). LABs concentrations ranged from 7.1 to 41.3ngg−1 dry weight (dw) in surficial sediments from Brunei Bay. The study results showed LABs concentrations variably due to the LABs intensity and anthropogenic influence along Brunei Bay in recent years. The ratio of Internal to External isomers (I/E ratio) of LABs in sediment samples from Brunei Bay ranged from 0.56 to 2.17 along Brunei Bay stations, indicating that the study areas were receiving primary and secondary effluents. This is the first study carried out to assess the distribution and sources of LABs in surface sediments from Brunei Bay, Brunei.
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