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Characterization of spatial patterns in river water quality using chemometric pattern recognition techniques
2012
Gazzaz, Nabeel M. | Yusoff, Mohd Kamil | Ramli, Mohammad Firuz | Ahmad Zaharin Aris, | Juahir, Hafizan
This study employed three chemometric data mining techniques (factor analysis (FA), cluster analysis (CA), and discriminant analysis (DA)) to identify the latent structure of a water quality (WQ) dataset pertaining to Kinta River (Malaysia) and to classify eight WQ monitoring stations along the river into groups of similar WQ characteristics. FA identified the WQ parameters responsible for variations in Kinta River’s WQ and accentuated the roles of weathering and surface runoff in determining the river’s WQ. CA grouped the monitoring locations into a cluster of low levels of water pollution (the two uppermost monitoring stations) and another of relatively high levels of river pollution (the mid-, and down-stream stations). DA confirmed these clusters and produced a discriminant function which can predict the cluster membership of new and/or unknown samples. These chemometric techniques highlight the potential for reasonably reducing the number of WQVs and monitoring stations for long-term monitoring purposes.
Afficher plus [+] Moins [-]A marine secondary producer respires and feeds more in a high CO₂ ocean
2012
Li, Wei | Gao, Kunshan
Climate change mediates marine chemical and physical environments and therefore influences marine organisms. While increasing atmospheric CO₂ level and associated ocean acidification has been predicted to stimulate marine primary productivity and may affect community structure, the processes that impact food chain and biological CO₂ pump are less documented. We hypothesized that copepods, as the secondary marine producer, may respond to future changes in seawater carbonate chemistry associated with ocean acidification due to increasing atmospheric CO₂ concentration. Here, we show that the copepod, Centropages tenuiremis, was able to perceive the chemical changes in seawater induced under elevated CO₂ concentration (>1700μatm, pH<7.60) with avoidance strategy. The copepod’s respiration increased at the elevated CO₂ (1000μatm), associated acidity (pH 7.83) and its feeding rates also increased correspondingly, except for the initial acclimating period, when it fed less. Our results imply that marine secondary producers increase their respiration and feeding rate in response to ocean acidification to balance the energy cost against increased acidity and CO₂ concentration.
Afficher plus [+] Moins [-]Mapping the pollutants in surface riverine flood plume waters in the Great Barrier Reef, Australia
2012
Devlin, M.J. | McKinna, L.W. | Álvarez-Romero, J.G. | Petus, C. | Abott, B. | Harkness, P. | Brodie, J.
The extent of flood plume water over a 10year period was mapped using quasi-true colour imagery and used to calculate long-term frequency of occurrence of the plumes. The proportional contribution of riverine loads of dissolved inorganic nitrogen, total suspended sediments and Photosystem-II herbicides from each catchment was used to scale the surface exposure maps for each pollutant. A classification procedure was also applied to satellite imagery (only Wet Tropics region) during 11 flood events (2000–2010) through processing of level-2 ocean colour products to discriminate the changing characteristics across three water types: “primary plume water”, characterised by high TSS values; “secondary plume water”, characterised by high phytoplankton production as measured by elevated chlorophyll-a (chl-a), and “tertiary plume water”, characterised by elevated coloured dissolved and detrital matter (CDOM+D). This classification is a first step to characterise flood plumes.
Afficher plus [+] Moins [-]Impacts of human activities on coral reef ecosystems of southern Taiwan: A long-term study
2012
Liu, Pi-Jen | Meng, Pei-Jie | Liu, Li-Lian | Wang, Jih-Terng | Leu, Ming-Yih
In July 2001, the National Museum of Marine Biology and Aquarium, co-sponsored by the Kenting National Park Headquarters and Taiwan’s National Science Council, launched a Long-Term Ecological Research (LTER) program to monitor anthropogenic impacts on the ecosystems of southern Taiwan, specifically the coral reefs of Kenting National Park (KNP), which are facing an increasing amount of anthropogenic pressure. We found that the seawater of the reef flats along Nanwan Bay, Taiwan’s southernmost embayment, was polluted by sewage discharge at certain monitoring stations. Furthermore, the consequently higher nutrient and suspended sediment levels had led to algal blooms and sediment smothering of shallow water corals at some sampling sites. Finally, our results show that, in addition to this influx of anthropogenically-derived sewage, increasing tourist numbers are correlated with decreasing shallow water coral cover, highlighting the urgency of a more proactive management plan for KNP’s coral reefs.
Afficher plus [+] Moins [-]Environmentally safe areas and routes in the Baltic proper using Eulerian tracers
2012
Höglund, A. | Meier, H.E.M.
In recent years, the shipping of environmentally hazardous cargo has increased considerably in the Baltic proper. In this study, a large number of hypothetical oil spills with an idealized, passive tracer are simulated. From the tracer distributions, statistical measures are calculated to optimize the quantity of tracer from a spill that would stay at sea as long as possible. Increased time may permit action to be taken against the spill before the oil reaches environmentally vulnerable coastal zones. The statistical measures are used to calculate maritime routes with maximum probability that an oil spill will stay at sea as long as possible. Under these assumptions, ships should follow routes that are located south of Bornholm instead of the northern routes in use currently. Our results suggest that the location of the optimal maritime routes depends on the season, although interannual variability is too large to identify statistically significant changes.
Afficher plus [+] Moins [-]Embryotoxic and genotoxic effects of heavy metals and pesticides on early life stages of Pacific oyster (Crassostrea gigas)
2012
Mai Hương, | Cachot, Jérôme | Brune, Justine | Geffard, Oliver | Belles, Angel | Budzinski, Hélène | Morin, Bénédicte
This study evaluated embryotoxicity and genotoxicity of two dissolved metals copper and cadmium (Cu and Cd) and two pesticides (metolachlor and irgarol) occurring in Arcachon Bay (SW France) in Pacific oyster (Crassostrea gigas) larvae and investigated the relationship between those two endpoints. Embryotoxicity was measured by calculating the percentage of abnormal D-shaped larvae and genotoxicity was evaluated with DNA strand breaks using the comet assay. After 24h exposure, significant increases of the percentage of abnormal D-larvae and the DNA strand breaks were observed from 0.1μgL⁻¹ for Cu, 10μgL⁻¹ for Cd and 0.01μgL⁻¹ for both irgarol and metolachlor in comparison with the controls. A strong positive relationship between embryotoxicity and genotoxicity was recorded for Cu, Cd and metolachlor. The current study suggests that copper, irgarol and metolachlor can induce larval abnormalities and DNA damage in a population of exposed oysters at environmentally relevant concentrations.
Afficher plus [+] Moins [-]A strategy for detecting derelict fishing gear at sea
2012
McElwee, Kris | Donohue, Mary J. | Courtney, Catherine A. | Morishige, Carey | Rivera-Vicente, Ariel
Derelict fishing gear (DFG) is a highly persistent form of marine pollution known to cause environmental and economic damage. At-sea detection of DFG would support pelagic removal of this gear to prevent and minimize impacts on marine environments and species. In 2008, experts in marine debris, oceanography, remote sensing, and marine policy outlined a strategy to develop the capability to detect and ultimately remove DFG from the open ocean. The strategy includes three interrelated components: understanding the characteristics of the targeted DFG, indirectly detecting DFG by modeling likely locations, and directly detecting pelagic DFG using remote sensing. Together, these components aim to refine the search area, increase the likelihood of detection, and decrease mitigation response time, thereby providing guidance for removal operations. Here, we present this at-sea detection strategy, relate it to relevant extant research and technology, and identify gaps that currently prevent successful at-sea detection and removal of DFG.
Afficher plus [+] Moins [-]PCBs, PBDEs and organochlorine pesticides in crabs Hepatus pudibundus and Callinectes danae from Santos Bay, State of São Paulo, Brazil
2012
Magalhães, C.A. | Taniguchi, S. | Cascaes, M.J. | Montone, R.C.
The occurrence of persistent organic pollutants (POPs) as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDE) in crabs Hepatus pudibundus and Callinectesdanae was assessed from two different places inside of the Santos Bay and Moela Island near one of the most economically important metropolitan areas in Southern Brazil. Among POPs analyzed, ∑PCBs (222–923ngg⁻¹lipid weight) and ∑DDTs (154–410ngg⁻¹lw) exhibited the highest concentrations in the crabs. ∑HCHs ranged from 10.3 to 30.9ngg⁻¹lw and were found in all individuals. Other OCPs found in lower concentration was Mirex (7.6–41.6ngg⁻¹lw) and HCB (5.83–16.9ngg⁻¹lw). ∑PBDEs (24.1ngg⁻¹lw) were only found in one male individual from the species C. danae collected near to the submarine sewage of Santos. Male crabs showed higher POP concentrations than female crabs for those two species.
Afficher plus [+] Moins [-]Trace metal pollution and its influence on the community structure of soft bottom molluscs in intertidal areas of the Dar es Salaam coast, Tanzania
2012
Rumisha, Cyrus | Elskens, Marc | Leermakers, Martine | Kochzius, Marc
The influence of trace metal pollution on the community structure of soft bottom molluscs was investigated in intertidal areas of the Dar es Salaam coast. Significant enrichment of As, Mn, Mo, Sb, and Zn in sediments was recorded. Redundancy analysis indicated that trace metal pollution contributed 68% of the variation in community structure. Monte Carlo permutation test showed that As and Sb contributed significantly to variation in species composition. T-value biplots and van Dobben circles showed that the gastropods Acteon fortis, Assiminea ovata, and Littoraria aberrans, were negatively affected by As and Sb, while the bivalve Semele radiata and the gastropod Conus litteratus were only negatively affected by As. Bioaccumulation of As, Cd, Cu, Mo and Zn occurred in the bivalve Mactra ovalina and the gastropod Polinices mammilla. This calls for regular monitoring and management measures.
Afficher plus [+] Moins [-]Antibiotic resistant pathogens versus human impacts: A study from three eco-regions of the Chennai coast, southern India
2012
Vignesh, Sivanandham | Muthukumar, Krishnan | Arthur James, Rathinam
We assessed the occurrence of pollution indicators and antibiotic resistant bacterial isolates from water and sediment samples of three different eco-regions of the Chennai coast between March – May of 2010. Total of 960 bacterial strains belonging to four genera were isolated which show the highest frequencies of resistance to vancomycin (53.6%) and penicillin (52.6%) (except Enterococcus sp., which is highly resistant to erythromycin) and lowest frequencies of resistance to chloramphenicol (3.43%), ciprofloxacin (3.95%), gentamicin (4.68%), and tetracycline (6.97%). The E. coli, Vibrio sp., Salmonella sp. and Enterococcus sp. show high frequency of resistance to 2–5 antibacterials of 60.4%, 45.83%, 69.16% and 46.6%, respectively. High pollution indices (PI – 6.66–14.06) and antibiotic resistance indices (ARI – 0.29–0.343) indicate that the coastal environment is highly exposed to antibiotic sources that suggesting to avoid direct contact.
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