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Anthropogenic Input (anthropogenic + input)
Selected AbstractsDissolved fraction of standard laboratory cladoceran food alters toxicity of waterborne silver to Ceriodaphnia dubia,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008Jason M. Kolts Abstract The biotic ligand model (BLM) for the acute toxicity of cationic metals to aquatic organisms incorporates the toxicity-modifying effects of dissolved organic matter (DOM), but the default parameterization (i.e., assuming 10% of DOM is humic acid) does not differentiate DOM from different sources. We exposed a cladoceran (Ceriodaphnia dubia) to Ag in the presence of DOM from filtered YCT (standard yeast,Cerophyll®,trout chow food recommended by the U.S. Environmental Protection Agency [EPA] for cladocerans), from the Suwannee River (GA, USA; relatively little anthropogenic input), and from the Desjardins Canal in Hamilton (ON, Canada; receives treated municipal wastewater effluent). In all three treatments, the dissolved organic carbon (DOC) concentration was 2 mg/L (the concentration following addition of YCT slurry at the U.S. EPA,recommended volume ratio). The average 48-h median effects concentration (EC50) ratios for dissolved Ag in the presence and absence of DOM [i.e., (EC50 with DOM)/(EC50 without DOM)] were as follows: Suwannee River, 1.6; Desjardins Canal, 2.2; and YCT filtrate, 26.8. Therefore, YCT filtrate provided much more protection against Ag toxicity than that provided by DOM from the surface waters. The major spectral characteristic that differentiated YCT filtrate from the other two types of DOM was a strong tryptophan peak in the excitation,emission matrix for YCT. These results have important implications for interpreting Ag toxicity tests in which organisms are fed YCT, and they suggest BLM-calculated toxicity predictions might be improved by incorporating specific chemical constituents or surrogate indices of DOM. Another component of the protective effect against Ag toxicity, however, might be that the dissolved fraction of YCT served as an energy and/or nutrient source for C. dubia. [source] The formation and sedimentary infilling of the Cave of Hearths and Historic Cave complex, Makapansgat, South AfricaGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2004A.G. Latham The archaeology of caves is best served by including a study of natural effects prior to and during anthropogenic input. This is especially true for the Cave of Hearths because not only has erosion determined the area of occupation, but also subsequent undermining has caused collapse of some of the rearward parts of the site during Early Stone Age (Acheulian) and later times; and this had a major impact on excavation. The key to understanding the nature of the collapsed layers was the rediscovery of a lower part of the cavern below the whole site. This lower cavern is no longer accessible, but the evidence for it was revealed in a swallow hole by R.J. Mason, and in archived material at the Department of Archaeology, University of Witwatersrand. The creation and dissolution of dolomite fragments in the upper layers has resulted in the formation of thick, carbonate-cemented breccia that has preserved underlying layers and prevented further collapse. We agree with Mason that further archaeological and hominid finds await excavation under the proximate Historical Cave west entrance. This area has the potential for archaeological and palaeoanthropological material that predates the layers in the Cave of Hearths. © 2004 Wiley Periodicals, Inc. [source] Atmospheric nitrogen deposition has caused nitrogen enrichment and eutrophication of lakes in the northern hemisphereGLOBAL CHANGE BIOLOGY, Issue 4 2006ANN-KRISTIN BERGSTRÖM Abstract We compiled chemical data and phytoplankton biomass (PB) data (chlorophyll a) from unproductive lakes in 42 different regions in Europe and North America, and compared these data to inorganic nitrogen (N) deposition over these regions. We demonstrate that increased deposition of inorganic N over large areas of Europe and North America has caused elevated concentrations of inorganic N in lakes. In addition, the unproductive lakes in high N deposition areas had clearly higher PB relative to the total phosphorus (P) concentrations illustrating that the elevated inorganic N concentrations has resulted in eutrophication and increased biomass of phytoplankton. The eutrophication caused by inorganic N deposition indicates that PB yield in a majority of lakes in the northern hemisphere is (was) limited by N in their natural state. We, therefore, suggest that P limitation largely concerns lakes where the balance between N and P has been changed because of increased anthropogenic input of N. [source] ECOSYSTEM MODELING: A TOOL TO UNDERSTAND THE INTERACTIONS BETWEEN EXTRACTIVE AND FED AQUACULTUREJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Yarish, C. 1, Rawson, Jr. M. V.2, Chopin, T.3, Wang, D. R.4, Chen, C.4, Carmona, R.1, Chen, C.5 , Wang, L.4, Ji , R.5 and Sullivan, J.5 1University of Connecticut, Stamford, Connecticut 06901-2315, USA; 2Georgia Sea Grant College Program, Athens, GA 30602-3636, USA; 3University of New Brunswick, Saint John, NB, E2L 4L5, Canada; 4Marine and Fishery Dept. of Hainan Province, Haikou, Hainan, P. R. China; 5The University of Georgia, Athens, GA 30602-3636, USA One of the most difficult tasks resource managers face is understanding the carrying capacity of coastal waters for aquaculture. Aquaculture, like many other human activities, can threaten coastal waters. Aquaculture producing shrimp and finfish depends on supplemental feeding and can contribute to eutrophication. A second type, involving shellfish and macroalgae, extracts plankton and nutrients from surrounding waters, and can have a significant positive impact on moderately eutrophic waters. Ecosystem modeling offers a 3-dimensional physical, chemical and biological simulation that can help understand and predict the impacts of aquaculture on coastal embayments. Such a model is being explored for Xincun Bay (22 km2), which is located in southeastern Hainan Province, China. Aquaculture in Xincun Bay includes 6500 fish pens, 100 ha of shrimp ponds, pearl oyster culture rafts and Kappaphycus alvarezii culture that produces 2,000 mt (Oct.-May). The surrounding area has ~ 15,000 people and Xincun City is a major offshore fishing and tourist center. The annual nitrogen and phosphorus removal capacity of Kappaphycus in Xincun Bay may have been in the order of 53.8 and 3.7 mt, respectively, during the 1999-2000 growing season. Lian Bay (~ 15 km2), a nearby bay with only Kappaphycus and pearl oyster culture (and little anthropogenic input), has a macroalgal production of 1,500 mt annually. The annual nitrogen and phosphorus removal capacity of Kappaphycus here may have been in the order of 25 and 0.33 mt, respectively. Our prototype model may hold the promise for showing the importance of integrating seaweed culture activities in the maintenance and health of coastal embayments. [source] Biological significance of metals partitioned to subcellular fractions within earthworms (Aporrectodea caliginosa),ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Martina G. Vijver Abstract Metal ions in excess of metabolic requirements are potentially toxic and must be removed from the vicinity of important biological molecules to protect organisms from adverse effects. Correspondingly, metals are sequestrated in various forms, defining the accumulation pattern and the magnitude of steady-state levels reached. To investigate the subcellular fractions over which Ca, Mg, Fe, Cu, Zn, Cd, Pb, Ni, and As are distributed, earthworms (Aporrectodea caliginosa) collected from the field were analyzed by isolating metal-rich granules and tissue fragments from intracellular microsomal and cytosolic fractions (i.e., heat-stable proteins and heat-denatured proteins). The fractions showed metal-specific binding capacity. Cadmium was mainly retrieved from the protein fractions. Copper was equally distributed over the protein fraction and the fraction comprising tissue fragments, cell membranes, and intact cells. Zinc, Ca, Mg, and As were mainly found in this fraction as well. Lead, Fe, and Ni were mainly isolated from the granular fraction. To study accumulation kinetics in the different fractions, three experiments were conducted in which earthworms were exposed to metal-spiked soil and a soil contaminated by anthropogenic inputs and, indigenous earthworms were exposed to field soils. Although kinetics showed variation, linear uptake and steady-state types of accumulation patterns could be understood according to subcellular compartmentalization. For risk assessment purposes, subcellular distribution of metals might allow for a more precise estimate of effects than total body burden. Identification of subcellular partitioning appears useful in determining the biological significance of steady-state levels reached in animals. [source] Exploring the diversity of bacterial communities in sediments of urban mangrove forestsFEMS MICROBIOLOGY ECOLOGY, Issue 1 2008Newton C. Marcial Gomes Abstract Municipal sewage, urban runoff and accidental oil spills are common sources of pollutants in urban mangrove forests and may have drastic effects on the microbial communities inhabiting the sediment. However, studies on microbial communities in the sediment of urban mangroves are largely lacking. In this study, we explored the diversity of bacterial communities in the sediment of three urban mangroves located in Guanabara Bay (Rio de Janeiro, Brazil). Analysis of sediment samples by means of denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments suggested that the overall bacterial diversity was not significantly affected by the different levels of hydrocarbon pollution at each sampling site. However, DGGE and sequence analyses provided evidences that each mangrove sediment displayed a specific structure bacterial community. Although primer sets for Pseudomonas, alphaproteobacterial and actinobacterial groups also amplified ribotypes belonging to taxa not intended to be enriched, sequence analyses of dominant DGGE bands revealed ribotypes related to Alteromonadales, Burkholderiales, Pseudomonadales, Rhodobacterales and Rhodocyclales. Members of these groups were often shown to be involved in aerobic or anaerobic degradation of hydrocarbon pollutants. Many of these sequences were only detected in the sampling sites with high levels of anthropogenic inputs of hydrocarbons. Many dominant DGGE ribotypes showed low levels of sequence identity to known sequences, indicating a large untapped bacterial diversity in mangrove ecosystems. [source] Stratigraphy and formation processes of the Upper Pleistocene deposit at Gruta da Oliveira, Almonda karstic system, Torres Novas, PortugalGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 3 2009Diego E. Angelucci Gruta da Oliveira is a cave located in the Almonda karstic system in central Portugal. Its Upper Pleistocene fill is made up of gravitational sediments with varied biogenic and anthropogenic inputs. The archaeological sequence (35,70 ka) is fairly homogeneous, reflecting a predominantly moist climatic context modulated by millennial-scale variations. Human occupation was almost continuous throughout. In the richer archaeological layers (8,14), the anthropogenic components are in primary position, and post-depositional processes are restricted, although penecontemporaneous biological activity,such as hyena scavenging,overprinted the record. In layers 15,19, the excavated area corresponds to the footslope of a talus, where accumulation proceeded mainly through runoff and where the lithics and bones derive from occupations situated ca. 5m outward. The base of the deposit is >2m from the current base of the excavation, suggesting that Oxygen Isotope Stage (OIS)-4 and OIS-5 sediments underlay the deposit already exposed. This study confirms the archaeological integrity of the Mousterian assemblages found in the different layers, and, given the dates for layer 8, supports the hypothesis that Neanderthals survived in western Iberia until at least 35,000,38,000 calendar years ago. © 2009 Wiley Periodicals, Inc. [source] Possible solar control on primary production along the Indian west coast on decadal to centennial timescale,JOURNAL OF QUATERNARY SCIENCE, Issue 2 2009Siby Kurian Abstract Using multiple geochemical proxies including specific biomarkers (dinosterol, phytol, stigmasterol and , -sitosterol) measured in a high-sedimentation rate core collected from the inner shelf (depth ,45,m) off Goa (India), we reconstruct surface productivity, which is mainly controlled by the monsoon upwelling in this region, during the last ca. 700 a. Surface productivity appears to have varied in tandem with the Konkan,Goa rainfall and sunspot activity during the instrumental period (last 250 a). The productivity proxies also covary with the total solar irradiance reconstructed for the period beyond the instrumental era, within the considerable uncertainty of the age model. This suggests that solar forcing may control coastal upwelling intensity and biological productivity in the eastern Arabian Sea on decadal to centennial timescales. During the late Anthropocene (last ca. 50 a), steep increases in all four biomarkers indicate greatly enhanced productivity in response to high solar irradiance as well as anthropogenic inputs of nutrients. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||