Search results for " Fish"
showing 10 items of 1414 documents
The dynamics of soil bacterial community structure in response to yearly repeated agricultural copper treatments
2008
International audience; The annual dynamics of soil bacterial community structure, including early, dose-dependent and transient modifications, was observed consecutively at different levels of copper contamination (high: 48 kg Cu ha−1, low: 16 kg Cu ha−1) repeated yearly over a three-year field experiment. Repeated low-level Cu contamination led to an increase in community stability to metal stress without a long-term shift in the population structure, whereas repeated high-level Cu contamination induced a novel and stable bacterial community structure. Furthermore, field experimentation highlighted that episodic climatic stress can modulate copper impact by enhancing community stability.
Horizontal distribution of copper, nickel and enchytraeid worms in polluted soil
1999
We studied the horizontal distribution of Cu, Ni and enchytraeid worms (Cognettia sphagnetorum, Vejdovsky, Oligochaeta, Enchytraeidae) in forest soil near a Cu–Ni smelter in SW Finland. Soil samples were taken from a polluted site (2 km from the smelter) and a reference area (8 km from the smelter). We used a hierarchical sampling design in the polluted area for studying possible scale-dependent variability in parameters measured, distance between the samples (different scales) being 5, 50 and 500 cm. Distribution of metals was moderately heterogeneous in the polluted soil; coefficient of variances (CV), 26% for Cu and 32% for Ni. Instead, distribution of enchytraeids in the area was highly…
Spatial Distribution of Soil Hydrological Properties in the Kilombero Floodplain, Tanzania
2017
Analysis and interpretation of soil properties dynamics is a keystone in understanding the hydrologic responses and yield potential of floodplain wetlands. This study characterizes the distribution and spatial trends of selected soil physical properties in the Kilombero floodplain, Tanzania. A total of 76 composite soil samples were taken from 0 to 20 cm and 20 to 40 cm depth in a regular grid design across three hydrological zones, related to flooding intensity defined as fringe, middle, and riparian during the rainy season of 2015. The samples were analyzed for soil texture, bulk density, organic carbon, and saturated hydraulic conductivity. Seasonal soil moisture content was monitored at…
Dependence of accelerated degradation of atrazine on soil pH in French and Canadian soils
2000
Abstract A series of agricultural soils varying in their atrazine treatment history were sampled from 12 sites in France and two sites in Canada. The soils varied widely with respect to soil chemical, physical and microbiological (total microbial biomass, kinetics of C and N mineralization) properties. Soils treated with as few as two successive atrazine field applications mineralized [U- ring - 14 C]atrazine significantly more rapidly in 35 d laboratory incubations than did soils which had never received atrazine. Longer treatment history tended to favour more rapid mineralization in the so-called “adapted” soils. Up to 80% of the initially applied 14 C-atrazine was mineralized at the end …
Effect of rhamnolipids on microbial biomass content and biochemical parameters in soil contaminated with coal tar creosote
2019
AbstractThe objective of the present study was to compare the effect of rhamnolipids on the microbial biomass content and the activity of dehydrogenases (DHA), acid phosphatase (ACP), alkaline phosphatase (ALP), and urease (URE) in soil contaminated with two types of coal tar creosote: type C and type GX-Plus. The experiment was carried out on samples of sandy clay loam under laboratory conditions. Coal tar creosote was added to soil samples at a dose of 0 and 10 g·kg−1 DM, along with rhamnolipids at a dose of 0, 10, 100, and 1000 mg·kg−1 DM. The humidity of the samples was brought to 60% maximum water holding capacity, and the samples were incubated at 20°C. Microbial and biochemical param…
Factors Influencing Point Measurement of Near-surface Saturated Soil Hydraulic Conductivity in a Small Sicilian Basin
2017
Hydraulic conductivity of saturated soil, Ks, controls many hydrological processes. Parameterization of basin hydrological models in terms of Ks is complicated and uncertain owing to the very high spatial variability of this soil property. A small Sicilian basin was intensively sampled by the simplified falling head technique to obtain spatially distributed Ks data, and an attempt to explain their spatial variability on the basis of soil physical characteristics, digital elevation model-derived topographic attributes and land cover was carried out. High Ks values were obtained when clay content was low and both elevation and mean slope were high. Moreover, differences in Ks among land cover…
Estimating saturated soil hydraulic conductivity by the near steady-state phase of a Beerkan infiltration test
2017
Abstract Single-ring infiltration experiments carried out in the field, such as the Beerkan runs, allow easy and inexpensive characterization of soil hydraulic properties, and specifically saturated soil hydraulic conductivity, Ks, by maintaining the functional connection of the sampled soil volume with the surrounding soil. However, a single infiltration experiment is not enough to determine Ks. The simplest way to obtain the necessary additional data is based on the assessment of the soil texture and structure characteristics. In this investigation, a simplified method, named SSBI (Steady version of the Simplified method based on a Beerkan infiltration run), was developed to estimate Ks b…
Effects of solarisation on soil thermal-physical properties under different soil treatments: A review
2020
Solarisation technology allows for improving soil quality as well as crop productivity. The influence of the properties and method of use of plastic materials used to cover soils, such as the number and thickness of layers, and colour of the material, significantly alters soil thermal-physical properties. These effects can be managed and modified to increase solarisation efficiency by achieving a decrease in vapour movement between the soil surface and the atmosphere. Also, soil solarisation establishes microclimates that increase the effectiveness of fertilisers, thus modifying the soil thermal-physical properties. However, there is a lack of complete and general overview of this widely us…
Testing a new automated single ring infiltrometer for Beerkan infiltration experiments
2015
International audience; The Beerkan method along with BEST algorithms is an alternative technique to conventional laboratory or field measurements for rapid and low-cost estimation of soil hydraulic properties. The Beerkan method is simple to conduct but requires an operator to repeatedly pour known volumes of water through a ring positioned at the soil surface. A cheap infiltrometer equipped with a data acquisition system was recently designed to automate Beerkan infiltration experiments. In this paper, the current prototype of the automated infiltrometer was tested to validate its applicability to the Beerkan infiltration experiment under several experimental circumstances. In addition, t…
Halfway up the trophic chain: development of parasite communities in the sparid fish Boops boops
2007
SUMMARYWe examined the patterns of composition and structure of parasite communities in the Mediterranean sparid fish Boops boops along a gradient of fish sizes, using a large sample from a single population. We tested the hypothesis that species forming the core of the bogue parasite fauna (i.e. species which have a wide geographical range and are responsible for recognizable community structure) appear early in the fish ontogeny. The sequential community development observed supported the prediction that core species appear in the fish population earlier than rare and stochastic species. There was also a strong correlation between the order of ‘arrival’ of the species and their overall pr…