Small-Scale Distribution of Bacteria, Enzymatic Activities, and Organic Matter in Coastal Sediments

2001 ◽  
Vol 42 (2) ◽  
pp. 177-185 ◽  
Author(s):  
R. Danovaro ◽  
M. Armeni ◽  
A. Dell'Anno ◽  
M. Fabiano ◽  
E. Manini ◽  
...  
Polar Record ◽  
2003 ◽  
Vol 39 (4) ◽  
pp. 357-367 ◽  
Author(s):  
Sofia Koukina ◽  
Galina Korneeva ◽  
Lioudmila Ametistova ◽  
Tatiana Bek

Major (Al, Fe), minor (Mn), and trace (Li, Cu, Ni, Cr, Cd, Zn, Pb) metals along with nutrients (TOC, TON, TS, TP) and enzymatic activities were determined in 18 surface sediment and two soil samples collected in six small bays of the Karelian shore of Kandalaksha Bay, White Sea, Russian Arctic. The studied sediments tended to be marine, with a major input of organic matter from autochthonous sources. Marine organic material might be an important carrier of trace metals in the examined sediments. According to sediment quality guidelines, all trace-metal contents were below the threshold levels. The results of azocasein-trypsin tests also suggested no significant contamination of analysed sediments and soils. A comparison of the trace-metal contents in the sediments examined with those of the western Arctic shelf showed higher levels of Zn and Cr in the Karelian shore. Presumably these disparities were related to regional differences in sediment chemistries rather than to any enhanced pollution within the studied area. Both geochemical composition and enzymatic-activities patterns among sites studied are largely controlled by the sediment granulometry. The evolution of sediments in the restricted exchange environments under investigation is caused by depositional conditions, which are strongly affected by small-scale hydrodynamic processes specific for each particular area. The most vivid examples are separating basins, where the fine-grained sediments enriched in organic matter — and thus in nutrients and metals — are formed under calm hydrodynamic conditions enhanced by severely restricted water exchange.


2016 ◽  
Vol 28 (0) ◽  
Author(s):  
Nilva Brandini ◽  
◽  
Ana Paula de Castro Rodrigues ◽  
Ilene Matanó Abreu ◽  
Luiz Carlos Cotovicz Junior ◽  
...  

Abstract Aim: There are few studies dealing with the biogeochemical processes occurring in small estuaries receiving high sewage loading in tropical regions. The aim of this investigation was to characterize the biogeochemical behavior of nutrients in superficial waters collected at the Iguaçu estuarine system, during specific conditions (neap tide), located at the inner sector of a heavily eutrophicated embayment (Guanabara Bay, SE Brazil). Methods Physical and chemical variables were measured in situ (pH, temperature, conductivity, salinity, total dissolved solids, transparency, dissolved oxygen), whereas suspended particulate matter, chlorophyll a, phaepigments and nutrients (carbon, nitrogen and phosphorus forms) were measured in laboratory across the mesohaline estuarine gradient. Results The Iguaçu River mouth is in a high stage of eutrophication, considering nutrient concentrations, chlorophyll a and transparency of water column. Results indicate a transition from heterotrophic conditions to autotrophic conditions, since the nutrients concentrations showed a decreasing pattern along the saline gradient, while the chlorophyll an increased over the transects. The pH values and chlorophyll : phaeopigments ratios are significantly related to the amount and quality of organic matter contents, especially at transects under strong marine influence. More than 95% of the dissolved and total nitrogen concentrations are represented by NH4+ contributions, which are related to the ammonification of organic matter contents in this region, indicating the existence of untreated sewage loads in this area. Conclusion In this study, the Iguaçu River seemed to contribute with high inputs of nutrients that support important phytoplankton production at the inner regions of the bay related to the CO2 sink and autotrophic metabolism, showing the importance of verifying the biogeochemical behaviors of nutrients in estuarine areas, even in small scale.


2018 ◽  
Vol 247 ◽  
pp. 138-146 ◽  
Author(s):  
Mukesh Kumar Awasthi ◽  
Quan Wang ◽  
Hongyu Chen ◽  
Sanjeev Kumar Awasthi ◽  
Meijing Wang ◽  
...  

2018 ◽  
Vol 612 ◽  
pp. 636-648 ◽  
Author(s):  
Hendryk Czech ◽  
Toni Miersch ◽  
Jürgen Orasche ◽  
Gülcin Abbaszade ◽  
Olli Sippula ◽  
...  

2004 ◽  
Vol 61 (8) ◽  
pp. 1493-1502 ◽  
Author(s):  
R K Johnson ◽  
M L Ostrofsky

Sediment concentrations of total and available nitrogen (N), phosphorus (P), and potassium (K) and organic matter from the littoral zone of Lake Pleasant, Pennsylvania, were highly variable. Only organic matter and total N were correlated with depth, however. This result suggests the existence of more complex environmental gradients than the prevailing paradigm of monotonic changes in sediment characteristics with increasing depth. The spatial heterogeneity of submersed aquatic plant communities was significantly correlated with depth, and available N and P. Canonical correspondence analysis demonstrated that these three factors explained 38% of the variance in community structure. Other sediment characteristics (available K, organic matter, and total N, P and K) were not significant by themselves, but all variables combined explained 63% of community-structure variance. Cluster analysis identified species or groups of species typical of endpoints on the depth versus nutrient axes. Myriophyllum exalbescens was typical of deep sites with relatively nutrient-rich sediments, whereas deep nutrient-poor sites were dominated by Vallisneria americana and Megalodonta beckii. Shallow nutrient-rich sites were dominated by several species of Potamogeton and Elodea canadensis, and shallow nutrient-poor sites were dominated by Heteranthera dubia and Najas flexilis. These results demonstrate the importance of sediment characteristics in determining macrophytes' community structure within lakes.


2015 ◽  
Vol 12 (15) ◽  
pp. 4565-4575 ◽  
Author(s):  
C. Sanz-Lázaro ◽  
T. Valdemarsen ◽  
M. Holmer

Abstract. Increasing ocean temperature due to climate change is an important anthropogenic driver of ecological change in coastal systems. In these systems sediments play a major role in nutrient cycling. Our ability to predict ecological consequences of climate change is enhanced by simulating real scenarios. Based on predicted climate change scenarios, we tested the effect of temperature and organic pollution on nutrient release from coastal sediments to the water column in a mesocosm experiment. PO43− release rates from sediments followed the same trends as organic matter mineralization rates, increased linearly with temperature and were significantly higher under organic pollution than under nonpolluted conditions. NH4+ release only increased significantly when the temperature rise was above 6 °C, and it was significantly higher in organic polluted compared to nonpolluted sediments. Nutrient release to the water column was only a fraction from the mineralized organic matter, suggesting PO43− retention and NH4+ oxidation in the sediment. Bioturbation and bioirrigation appeared to be key processes responsible for this behavior. Considering that the primary production of most marine basins is N-limited, the excess release of NH4+ at a temperature rise > 6 °C could enhance water column primary productivity, which may lead to the deterioration of the environmental quality. Climate change effects are expected to be accelerated in areas affected by organic pollution.


2014 ◽  
Vol 1073-1076 ◽  
pp. 619-627
Author(s):  
Fang She Yang ◽  
Shu Zhen Su ◽  
Juan Juan Zhang ◽  
Ci Fen Bi

In this paper, based on geostatistics and GIS techniques, spatial variation characteristics of soil organic matter (acronym: SOM) on a small scale were analyzed and discussed in east-one-branch gully (EG1) bed with the seabuckthorn flexible dam and the contrastive gully bed (which is non-vegetated any vegetation) located in zhun-ge-er county, Erdos, inner Mongolia, which belongs to the typical Pisha Sandstone area. The results show that the seabuckthorn can significantly increase SOM in the small catchment gully bed in the Pisha sandstone area, and the mean SOM content in gully bed with the seabuckthorn flexible dam is approximate 1.75 times that in the contrastive gully. Apparent spatial variation characteristics of SOM were found in the gully with the seabuckthorn flexible dam and the contrastive gully bed, moreover, the medium spatial autocorrelation of SOM was detected in gully bed with the seabuckthorn flexible dam, and the spatial variation of SOM was together led to by the structural and random variation at 1-6.5 m range, and of which the random variation accounts for 40%. Additional, the spatial autocorrelation of SOM in the contrastive gully bed is higher, the spatial variation of SOM was dominantly brought about by the structural variation at 1-4.5 m range, and of which the random variation accounts for 37%. Furthermore, the fractal dimension values reveal that dependence of SOM of the gully bed with the seabuckthorn flexible dam on spatial is weaker than that of the contrastive gully bed. It is judged that the seabuckthorn has an obvious effect on spatial distribution patterns and heterogeneity of SOM on a small scale.


2003 ◽  
Vol 33 (12) ◽  
pp. 2509-2513 ◽  
Author(s):  
Brian W Benscoter ◽  
R Kelman Wieder

Fire directly releases carbon (C) to the atmosphere through combustion of biomass. An estimated 1470 ± 59 km2 of peatland burns annually in boreal, western Canada, releasing 4.7 ± 0.6 Tg C to the atmosphere via direct combustion. We quantified within-site variation in organic matter lost via combustion in a bog peatland in association with the 116 000-ha Chisholm, Alberta, fire in 2001. We hypothesized that for peatlands with considerable small-scale microtopography (bogs and treed fens), hummocks will burn less than hollows. We found that hollows exhibit more combustion than hummocks, releasing nearly twice as much C to the atmosphere. Our results suggest that spatial variability in species composition and site hydrology within a landform and across a landscape could contribute to considerable spatial variation in the amounts of C released via combustion during peatland fire, although the magnitude of this variation may be dependent on fire severity.


2015 ◽  
Vol 116 ◽  
pp. 326-333 ◽  
Author(s):  
Kenji Nakamoto ◽  
Tadashi Hibino ◽  
Kazutoshi Hino ◽  
Narong Touch

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