Groundwater nitrogen (N) and phosphorus (P) transport from ditch-drained, cultivated fields has not been adequately investigated in the Chesapeake Bay watershed.We monitored hydrology and groundwater Nand P concentrations in 26 shallow (~3 m [10 ft]) wells for 27 months on a heavily ditched, poultry-grain farm on Maryland's Lower Eastern Shore. Water tables fluctuated above and below shallow di...

Responses of wetland carbon cycling to environmental changes, particularly changes in water table depth, which are the key determinants to control the ecological and biogeochemical functions of wetlands, are highly non-linear and complex due to the dynamic interactions of several physical and biological processes. Several field experiments have found that wetland productivities have a significa...

a field study was conducted to evaluate the possibility of using water table control techniques in the semi arid region of iran with special attention to its salinity management. the wtm consisted of three subirrigation treatments with water table controls set at 0.3, 0.5 and 0.7 m from the soil surface and a free drainage (fd) treatment. the electrical conductivity (ec) of water was 1.5 ds/m. ...

groundwater drought denotes the condition and hazard during a prolonged meteorological drought when groundwater resources decline and become unavailable or inaccessible for human use. the aim of this study is to identify the influencial factors on groundwater drought in hamadan- bahar watershed,iran, to understand the forcing mechanisms. the standardised precipitation index (spi) has been used ...

In this study we investigate the effect of a water table boundary on solute spreading during infiltration in the vadose zone of heterogeneous soils. It has been found recently that the presence of the water table significantly affects unsaturated flow in a heterogeneous vadose zone and causes the flow to be spatially nonstationary. Because a vadose zone is by definition bounded by the water tab...

Parasites should be better at infecting hosts from sympatric populations than allopatric populations most of the time (parasite local adaptation). In a previous study of a population of snail parasites (Microphallus sp.) from Lake Alexandrina, New Zealand, we found that Microphallus was more infective to snails (Potamopyrgus antipodarum) in shallow water but not in deep water. Here, we repeated...

We compared life-history traits and extinction risk of chondrichthyans (sharks, rays and chimaeras), a group of high conservation concern, from the three major marine habitats (continental shelves, open ocean and deep sea), controlling for phylogenetic correlation. Deep-water chondrichthyans had a higher age at maturity and longevity, and a lower growth completion rate than shallow-water specie...