Refinar búsqueda
Resultados 1141-1150 de 3,991
Internal bioerosion in dead and live hard corals in intertidal zone of Hormuz Island (Persian Gulf)
2016
Jafari, Mohammad Ali | Seyfabadi, Jafar | Shokri, Mohammad Reza
Internal macrobioeroders and their erosion rate in three live and dead coral genera (Favia, Platygyra and Porites) from the intertidal zone of the Hormuz Island were studied by collecting five live and five dead colonies from each genus, from which 4mm cross-sections were cut and photographed. Photos were analyzed using the Coral Point Count with Excel extensions. Totally, 9 taxa were identified: four bivalve species, one sponge, three polychaetes, and one barnacle. Bioerosion rate did not significantly differ among the three live corals, but among the dead ones only Porites was significantly more eroded than Favia. Sponge had the highest role in the erosion of the dead Platygyra, while barnacles were the most effective eroding organism in the live Platygyra. Polychaetes, followed by bivalves, were the most destructive bioeroders on the dead and live Porites. Further, none of the bioeroding organisms had selectively chosen either the dead or live Favia.
Mostrar más [+] Menos [-]Chemical Processes Affecting the Mobility of Heavy Metals and Metalloids in Soil Environments
2016
Caporale, Antonio G. | Violante, Antonio
The mobility, bioavailability, and toxicity of metal(loid)s are influenced by their interactions with phyllosilicates, organic matter, variable charge minerals, and microorganisms. Physicochemical processes influencing the chemistry of metal(loid)s in soil environments include sorption/desorption, solution complexation, oxidation-reduction, and precipitation-dissolution reactions. In particular, the sorption/desorption reactions of metal(loid)s on/from soil sorbents are influenced by pH, nature of soil components, and presence and concentrations of cations and inorganic anions. In recent years, many extraction tests have been used for assessing trace elements mobility and phytoavailability. Chemical speciation of toxic elements may be achieved by spectroscopic analyses (XAS), which provide information about oxidation state, symmetry, and identity of the coordinating ligand environment, and possible solid phases.
Mostrar más [+] Menos [-]Managing Groundwater Nitrate Contamination from Livestock Farms: Implication for Nitrate Management Guidelines
2016
Sahoo, Prafulla Kumar | Kim, Kangjoo | Powell, M. A.
Significant nitrate contamination of groundwater has been observed in various parts of the world; intensive livestock farming is one of the major causes. This paper reviews various guidelines/regulations, which have been developed in advanced countries such as USA, Canada, Australia, and Europe to combat this problem by designing effective monitoring and management programs. Monitoring programs deal mainly with selection of sites, number of monitoring wells, specific parameters, and sampling frequency, which are helpful for identifying the source and extend of the contamination. Management programs deal with selection of suitable location, site characterization, proximity of livestock facilities and drinking wells, and proper storage, maintenance of the facilities, and limits of manures application in order to minimize nitrate leaching into groundwater. The main aim of this paper is to help states/countries, which do not have any guideline, and consulting engineers/consultants/owners of livestock operation in the design of effective strategies for point source nitrate management.
Mostrar más [+] Menos [-]Combined nutrient and macroalgae loads lead to response in seagrass indicator properties
2016
Han, Qiuying | Soissons, Laura M. | Bouma, Tjeerd J. | van Katwijk, Marieke M. | Liu, Dongyan
Excess nutrients are potential factors that drive phase shifts from seagrasses to macroalgae. We carried out a manipulative field experiment to study the effects of macroalgae Ulva pertusa loading and nutrient addition to the water column on the nitrogen (N) and carbon (C) contents (i.e., fast indicators) as well as on the morphology and structure (i.e., slow indicators) of Zostera marina. Our results showed rapid impact of increased macroalgae and nutrient load on Z. marina C/N ratios. Also, macroalgae addition resulted in a trend of decreasing belowground biomass of seagrasses, and nutrient load significantly decreased above to belowground biomass ratio. Although some morphological/structural variables showed relatively fast responses, the effects of short-term disturbance by macroalgae and nutrients were less often significant than on physiological variables. Monitoring of seagrass physiological indicators may allow for early detection of eutrophication, which may initiate timely management interventions to avert seagrass loss.
Mostrar más [+] Menos [-]Unmanned vehicles for maritime spill response case study: Exercise Cathach
2016
Dooly, Gerard | Omerdic, Edin | Coleman, Joseph | Miller, Liam | Kaknjo, Admir | Hayes, James | Braga, José | Ferreira, Filipe | Conlon, Hugh | Barry, Hugh | Marcos-Olaya, Jesús | Tuohy, Thomas | Sousa, João | Toal, Dan
This paper deals with two aspects, namely a historical analysis of the use of unmanned vehicles (UAVs ROVs, AUVs) in maritime spill incidents and a detailed description of a multi-agency oil and HNS incident response exercise involving the integration and analysis of unmanned vehicles environmental sensing equipment. The exercise was a first in terms of the level of robotic systems deployed to assist in survey, surveillance and inspection roles for oil spills and harmful and noxious substances.
Mostrar más [+] Menos [-]The influence of wastewater discharge on water quality in Hawai'i: A comparative study for Lahaina and Kihei, Maui
2016
Miller-Pierce, Mailea R. | Rhoads, Neil A.
In Maui, Hawai'i, wastewater reclamation facilities (WWRFs) dispose of partially treated effluent into injection wells connected to the nearshore environment. Hawai'i State Department of Health data from 2004–2015 were assessed for qualitative trends in nutrient, turbidity, and Chlorophyll a water quality (WQ) impairments for fourteen marine sites on Maui Island. We introduce a novel method, the Qualitative Impact Percentage (QIP), to facilitate a qualitative comparison of disparate factors contributing to WQ impairment. Sites near the Lahaina WWRF in West Maui, which was found in violation of the Clean Water Act in 2014, had fewer exceedances and lower geometric means compared to sites near the Kihei WWRF. Our results suggest that WQ impairments may be a greater concern in Kihei than previously acknowledged. This paper attempts to raise the awareness of policymakers and the public and to encourage further research assessing the effects of the Kihei WWRF on the marine environment.
Mostrar más [+] Menos [-]Large amounts of marine debris found in sperm whales stranded along the North Sea coast in early 2016
2016
Unger, Bianca | Rebolledo, Elisa L Bravo | Deaville, Rob | Gröne, Andrea | IJsseldijk, Lonneke L. | Leopold, Mardik F. | Siebert, Ursula | Spitz, Jérôme | Wohlsein, Peter | Herr, Helena
30 sperm whales (Physeter macrocephalus) stranded along the coasts of the North Sea between January and February 2016. The gastro-intestinal tracts of 22 of the carcasses were investigated. Marine debris including netting, ropes, foils, packaging material and a part of a car were found in nine of the 22 individuals. Here we provide details about the findings and consequences for the animals. While none of the items was responsible for the death of the animal, the findings demonstrate the high level of exposure to marine debris and associated risks for large predators, such as the sperm whale.
Mostrar más [+] Menos [-]Abnormally high phytoplankton biomass near the lagoon mouth in the Huangyan Atoll, South China Sea
2016
Ke, Zhixin | Liu, Huajian | Wang, Junxing | Liu, Jiaxing | Tan, Yehui
Nutrient concentration and phytoplankton biomass were investigated in Huangyan Atoll in May 2015. The concentrations of nutrients were very low, and dissolved inorganic nitrogen was composed mainly of ammonia. Nitrogen likely was the primary limiting factor for phytoplankton growth. The spatial variation of phytoplankton biomass was significant among the lagoon, reef flats, and outer reef slopes. Extremely high chlorophyll a concentration and micro-phytoplankton abundance were found in the region near the lagoon mouth. This high phytoplankton biomass might be due to nutrient input from fishing vessels and phytoplankton aggregation driven by the southwestern wind. Our results indicate that phytoplankton biomass could be a reliable indicator of habitat differences in this coral reef ecosystem, and micro-phytoplankton seems to be more sensitive to nutrient input than pico-phytoplankton.
Mostrar más [+] Menos [-]Does Black Carbon Contribute to Eutrophication in Large Lakes?
2016
Odhiambo, Moses | Routh, Joyanto
Eutrophication is a major ecological crisis in water bodies. This is mainly driven by anthropogenic activities in the catchment that incorporate various nutrients. Input of nutrients can also be driven by atmospheric deposition, which has a large footprint that goes beyond local point source(s). In particular, black carbon (BC) can be a carrier of various nutrients and increase primary productivity in lakes. We need to monitor the input of BC in large water bodies to fully understand its role in driving primary productivity and change in trophic status.
Mostrar más [+] Menos [-]Bioaccumulation of polycyclic aromatic hydrocarbons, polychlorinated biphenyls and hexachlorobenzene by three Arctic benthic species from Kongsfjorden (Svalbard, Norway)
2016
Szczybelski, Ariadna S. | van den Heuvel-Greve, Martine J. | Kampen, Tineke | Wang, Chenwen | Brink, Nico W. van den | Koelmans, Albert A.
The predicted expansion of oil and gas (O&G) activities in the Arctic urges for a better understanding of impacts of these activities in this region. Here we investigated the influence of location, feeding strategy and animal size on the bioaccumulation of Polycyclic Aromatic Hydrocarbons (PAHs), Polychlorinated Biphenyls (PCBs) and Hexachlorobenzene (HCB) by three Arctic benthic species in Kongsfjorden (Svalbard, Norway). No toxicity was expected based on biota PAH critical body residues. Biota PCB levels were mainly below limit of detection, whereas samples were moderately polluted by HCB. PAH concentrations in biota and Biota Sediment Accumulation Factors (BSAFs) were generally higher in Blomstrandhalvøya than in Ny-Ålesund, which was explained by a higher abundance of black carbon in Ny-Ålesund harbour. BSAFs differed significantly among species and stations. We conclude that contaminant body residues are a less variable and more straightforward monitoring parameter than sediment concentrations or BSAFs in Arctic benthos.
Mostrar más [+] Menos [-]