Refinar búsqueda
Resultados 1701-1710 de 4,308
Production of sorbent from paper industry solid waste for oil spill cleanup Texto completo
2017
Demirel Bayık, G. | Altın, A.
The aim of the study is to select a cellulosic waste material from paper industry solid wastes and process it for sorbent production. Four different solid wastes were collected from a local paper production facility and rejects were selected due to its sorption capacity and processability. Oil sorption experiments were conducted according to the ASTM F 726-12 method. Effect of sorbent dosage, contact and dripping time, recovery of the oil, reusability of the sorbent and sorption from the water surface were also determined. Maximum oil sorption capacity was determined as 9.67, 12.92 and 12.84g/g for diesel oil, 0W30 and 10W30 motor oils respectively for the static test and 8.27, 10.45 and 11.69g/g for the dynamic test. An efficient and low-cost sorbent was produced from paper industry rejects that can be used on land and on water.
Mostrar más [+] Menos [-]Use of common carp (Cyprinus carpio) and Aeromonas salmonicida for detection of immunomodulatory effects of chemicals on fish Texto completo
2017
Nakayama, Kei | Yamashita, Ryohei | Kitamura, Shin-Ichi
To develop a test for assessing the immunomodulatory effects of chemical pollutants on fish, we evaluated the effects of dexamethasone on the natural host–pathogen interaction between common carp (Cyprinus carpio) and Aeromonas salmonicida. Carp were exposed to 1mgL−1 dexamethasone for the entire experimental period. One week after the exposure test started, the exposed fish, as well as unexposed fish, were bath-infected with A. salmonicida. One hundred percent mortality was observed in bacteria-infected fish exposed to dexamethasone, whereas no infection-associated mortality was observed in infected fish in the absence of dexamethasone exposure. In a separate experiment, dexamethasone exposure significantly suppressed hemolytic complement activity in bacteria-infected fish. These results clearly indicate that exposure to a high concentration of dexamethasone suppressed the carp immune system and caused subsequent mortality. Thus, this proposed test method is likely to be useful for evaluating the immunomodulatory effects of chemicals in fish.
Mostrar más [+] Menos [-]Superstars: Assessing nutrient thresholds for enhanced larval success of Acanthaster planci, a review of the evidence Texto completo
2017
Wolfe, Kennedy | Graba-Landry, Alexia | Dworjanyn, Symon A. | Byrne, Maria
Crown-of-thorns starfish, Acanthaster planci (COTS), predation is a major cause of coral reef decline, but the factors behind their population outbreaks remain unclear. Increased phytoplankton food resulting from eutrophication is suggested to enhance larval survival. We addressed the hypothesis that larval success is associated with particular chl-a levels in tightly controlled larval:algal conditions. We used chl-a conditions found on coral reefs (0.1–5.0μgchl-aL−1), including nominal threshold levels for disproportionate larval success (≥1.0μgchl-aL−1). High success to the juvenile occurred across an order of magnitude of chl-a concentrations (0.5–5.0μgchl-aL−1), suggesting there may not be a narrow value for optimal success. Oligotrophic conditions (0.1μgchl-aL−1) appeared to be a critical limit. With a review of the evidence, we suggest that opportunistic COTS larvae may be more resilient to low food levels than previously appreciated. Initiation of outbreak populations need not require eutrophic conditions.
Mostrar más [+] Menos [-]Settling velocity of microplastic particles of regular shapes Texto completo
2017
Khatmullina, Liliya | Isachenko, Igor
Terminal settling velocity of around 600 microplastic particles, ranging from 0.5 to 5mm, of three regular shapes was measured in a series of sink experiments: Polycaprolactone (material density 1131kgm−3) spheres and short cylinders with equal dimensions, and long cylinders cut from fishing lines (1130–1168kgm−3) of different diameters (0.15–0.71mm). Settling velocities ranging from 5 to 127mms−1 were compared with several semi-empirical predictions developed for natural sediments showing reasonable consistency with observations except for the case of long cylinders, for which the new approximation is proposed. The effect of particle's shape on its settling velocity is highlighted, indicating the need of further experiments with real marine microplastics of different shapes and the necessity of the development of reasonable parameterization of microplastics settling for proper modeling of their transport in the water column.
Mostrar más [+] Menos [-]The cumulative effects assessment of a coastal ecological restoration project in China: An integrated perspective Texto completo
2017
Ma, Deqiang | Zhang, Liyu | Fang, Qinhua | Jiang, Yuwu | Elliott, Michael
Large scale coastal land-claim and sea-enclosing (CLASE) activities have caused habitat destruction, biodiversity losses and water deterioration, thus the local governments in China have recently undertaken seabed dredging and dyke opening (SDADO) as typical ecological restoration projects. However, some projects focus on a single impact on hydrodynamic conditions, water quality or marine organisms. In a case study in Xiamen, China, an integrated effects assessment framework centres on ecohydrology, using modeling of hydrodynamic conditions and statistical analysis of water quality, was developed to assess the effects of ecological restoration projects. The benefits of SDADO projects include improving hydrodynamic conditions and water quality, as a precursor to further marine biological improvements. This study highlights the need to comprehensively consider ecological effects of SDADO projects in the planning stage, and an integrative assessment method combining cumulative effects of hydrodynamic conditions, water quality and biological factors.
Mostrar más [+] Menos [-]Heavy metals in the bottom sediments of the Furo of Laura estuary, Eastern Amazon, Brazil Texto completo
2017
Lima, M.W. | Santos, M.L.S. | Faial, K.C.F. | Freitas, E.S. | Lima, M.O. | Pereira, J.A.R. | Cunha, I.P.R.T.
The Furo of Laura is an economically important river in the Amazon estuary. Thus, in the present study, we evaluated the metal distribution (Al, Cd, Co, Cu, Cr, Fe, Ni, and Mg) in the bottom sediments of this river. The sediments were sampled at four points every 2months for a year with an Ekman-Birge sampler. After microwave acid digestion, the metal levels were determined by optical emission spectrometry with inductively coupled plasma. The particle size and organic matter content influenced the concentration of the metals. The sediments were not enriched by the analyzed metals; the estuary therefore retained the characteristics of an uncontaminated environment, thus serving as a reference environment for comparison.
Mostrar más [+] Menos [-]An approach based on M-AMBI for assessing benthic ecological status of a broad intertidal zone: A case study in the Jiangsu intertidal zone, China Texto completo
2017
Song, Qiaochu | Zou, Xinqing | Zhang, Hu | Yu, Wenwen | Zang, Zheng | Wang, Chenglong
Intensive anthropogenic activities have a serious negative effect on the Jiangsu coastal area of China, especially on the distinctive intertidal zone. Humans are trying to eliminate this effect by taking protection and eco-compensation measures. However, when trying to determine the ecological status and quantify the anthropogenic impact for this area, the complex relationship between ecosystems and environmental stress leads to difficulties in reflecting general environmental quality. This study assessed the benthic ecological status of 10 transects (three stations/transect) across six different typologies over six years (2007, 2009–2013) in the Jiangsu intertidal zone. A unitary assessment of each transect was conducted using the multivariate AZTI Marine Biotic Index (M-AMBI), along with a radar chart (and its parameters). In the Jiangsu intertidal zone, the ecological status was noted as good or moderate at most sampling stations. Among the six assessed years, 2010 had the highest ecological status, while 2007 had the lowest. As for transects, transect 1 had the highest ratings, and transect 3 had the lowest ratings. Various stresses and advantageous human intervention and contributed to the ecological status for the different areas. The M-AMBI could be used in the future as a suitable index to assess the benthic ecological status of the Jiangsu intertidal zone. In addition, the new unitary method validated in this study could be used to assess ecosystems with several small biotopes, while accurately reflecting environmental quality.
Mostrar más [+] Menos [-]Offshore sediments record the history of onshore iron ore mining in Goa State, India Texto completo
2017
Sebastian, Tyson | Nath, BNagender | Naik, Sangeeta | Borole, D.V. | Pierre, Salou | Yazing, Armoury Kazip
Environmental magnetic and geochemical analyses combined with 210Pb dating were carried out on a sediment core off Goa from Arabian Sea to reconstruct the sedimentation history of last three and a half centuries and to investigate the impact of onshore iron ore mining on the offshore sedimentation. A drastic increase in sedimentation rate and mineral magnetic concentration parameters divides the core into two units (1 & 2) at a depth of 41cm (1982CE). The high magnetic susceptibility values in Unit 1 sediments are coeval with increased iron ore production on land and illustrate the role of terrestrial mining on the increased offshore sedimentation. The early diagenetic signals were observed in Unit 2 of the core with low concentration parameters, coarse magnetic grain size and magnetically hard mineralogy. The geochemical data of the core also record the Little Ice Age (LIA) climatic events of Dalton and Maunder solar minima.
Mostrar más [+] Menos [-]Pollution levels and risks of polycyclic aromatic hydrocarbons in surface sediments from two typical estuaries in China Texto completo
2017
Wang, Chenglong | Zou, Xinqing | Li, Yali | Zhao, Yifei | Song, Qiaochu | Yu, Wenwen
To assess the environmental risks of polycyclic aromatic hydrocarbons (PAHs), 48 and 45 sediments were collected from the Yangtze River Estuary (YRE) and Pearl River Estuary (PRE), respectively. The toxicity equivalency concentration (TEQ) in the YRE and PRE were ranged from 1.68 to 76.13 and 9.28 to 129.24ngTEQg−1, respectively. Results of risk quotient suggest that ecological risks of two estuaries are at a moderate level, but are higher in the PRE than YRE. The increment lifetime cancer risks (ILCR) from the YRE via ingestion and dermal contact were 1×10−6 to 5.6×10−5 and 4×10−6 to 1.6×10−4, and ranged from 7×10−6 to 9.4×10−5 and 2×10−5 to 2.8×10−4 in the PRE. ILCR results suggest that some low and moderate cancer risk exists in the YRE and PRE. Therefore, monitoring and control measures should be carried out immediately to reduce or eliminate the risks to human health from environmental exposure.
Mostrar más [+] Menos [-]Evaluation of AhR-agonists and AhR-agonist activity in sediments of Liaohe River protected areas, China Texto completo
2017
Zhang, Yun | Ke, Xin | Gui, Shaofeng | Wu, Xiaoqiong | Wang, Chunyong | Zhang, Haijun
A total of 9 sediment samples of Liaohe River protected areas were collected to evaluate aryl hydrocarbon receptor agonists (AhR-agonists) and AhR-agonist activity via chemical analysis and in vitro H4IIE cell bioassay. Results indicated that bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (Bio-TEQs) ranged from 89.1 to 251.1pg/g dry weight. Concentrations of 16 EPA polycyclic aromatic hydrocarbons (PAHs), 12 dioxin-like polychlorinated biphenyls (PCBs), and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) ranged from 256.8 to 560.1ng/g, 79.2 to 416.2pg/g, and 199.6 to 538.4pg/g, respectively. According to potency balance analysis, TEQchems based on PAHs, PCBs, and PCDD/Fs could contribute 16.56% to 26.11% of Bio-TEQs. This could be explained by the potential existence of unidentified AhR-agonists and the potential non-additive interactions among AhR-agonists in sediment extracts. Through the different contributions to Bio-TEQs, this study confirms that PCDD/Fs were the main pollutants that induced significantly AhR-agonist activity in sediments of Liaohe River protected areas.
Mostrar más [+] Menos [-]