Seasonal Changes In Water Quality Research Articles

CONSEQUENCES OF THE KUROSHIO PATH FOR HYDRAULIC PHENOMENA AROUND SETO INLAND SEA

We examined the physical factors affecting annual and seasonal changes in water quality of the Seto Inland Sea, Japan by using the data measured by several institutions. The observed sea level height (SLH) and sea surface temperature (SST) at Cape Shiono and Cape Ashizuri were influenced by the Kuroshio path. This result suggests that an open boundary condition is sensitive to the annual/seasonal fluctuation of water quality in inland seas.The water quality in Seto Inland Sea is greatly related with the Kuroshio path. In the recent twenty years, the Kuroshio path changed periodically. The Kuroshio current often takes a meanderings path over 1980's and it tends to come alongside Kii peninsula over 1990's. Also, the salinity distribution in the inland sea changed periodically with the shifts of the Kuroshio path.

Characteristics and the Seasonal Changes in Water Quality of Small Rivers in a Rural Agricultural Catchment Area

Characteristics and the Seasonal Changes in Water Quality of Small Rivers in a Rural Agricultural Catchment Area

Seasonal dynamics of plankton communities and water chemistry in a eutrophic wetland (Lake Monger, Western Australia): implications for biomanipulation

In a large (70 ha) shallow (<2m deep) eutrophic wetland investigated between November 1988 and October 1989, there were marked seasonal changes in water quality and the composition of zooplankton, and to a lesser extent phytoplankton communities, with three distinct groupings evident: summer, winter–spring and autumn. Summer conditions were characterized by high levels of total P (689198 ˜g L –1 ), N limitation, blooms of Microcystis aeruginosa (mean chlorophyll a = 46630 ˜g L –1 ) and zooplankton communities dominated by cyclopoid copepods (Mesocyclops sp. and Microcyclops sp.). Winter–spring conditions were characterized by Secchi disk transparencies to the bed (chlorophyll a <50 ˜g L –1 ), low total P (7140 ˜g L–1 ) and zooplankton communities dominated byDaphnia carinata King. Autumn conditions represented an intermediate state between these two. Significant linear relationships were recorded between chlorophyll a and total P and between chlorophyll a and D. carinata. Abundances of hemipteran predators (Anisops sp.) were correlated with D. carinata, but the relationship did not appear to be causal. The decline in D. carinata in summer was attributed to food limitation. Reductions in nutrient inputs to the lake in 1990–91, resulted in improved water quality and high abundances of D. carinata during summer.

Changes in Water Quality via the Metabolic Process While Penetrating a Sandy Shore in a Shallow, Eutrophic Lake.

Lake water swashing up onto a sandy beach area penetrates the sandy layer before returning to the lake shore zone. As a result, materials contained in the lake water are metabolized, and the water quality of the penetrating water improves. To clarify the process involved, water samples were collected in collection vessels buried at locations 0.2, 0.5, 0.8 and 1.1 m from the shoreline, and seasonal changes in water quality were observed. Organic materials in the lake water were seen to decompose in the sandy beach zone with the organic phosphorus turning into inorganic phosphorus, and to then return almost completely to the lake shore zone. Organic nitrogen was turned mostly into nitrate with the concentration of total nitrogen decreasing as the sample site moved farther from the shoreline. The reduced N/P ratio in water penetrating toward the shoreline suggests the possibility of denitrification as the cause for the decrease in nitrogen concentration as the lake water swashed in and was filtered through the sandy layer.

Seasonal Changes in Water Quality in Commercial Channel Catfish Ponds in Mississippi

AbstractSelected water quality variables were measured at monthly intervals for 1 yr in 10 commercial channel catfish ponds in northwest Mississippi. Temporal changes in most variables appeared to be related to seasonal periodicity of phytoplankton abundance. Phytoplankton standing crops and total organic matter were highest in summer months when primary production was favored by warm water temperatures, high solar irradiance, and large inputs of nutrients resulting from high summer fish feed allowances. As day length, water temperature, and feed inputs decreased in autumn and winter, phytoplankton abundance and organic matter concentrations decreased. Seasonal changes in total nitrogen and total phosphorus concentrations were similar to phytoplankton abundance because much of the total nitrogen and phosphorus was contained within phytoplankton cells. Contrasting to the seasonal trend for total nitrogen, concentrations of dissolved inorganic nitrogen were lowest in the summer and highest in the cooler months. Rapid assimilation by phytoplankton served to maintain relatively low concentrations of dissolved inorganic nitrogen during the summer despite highest nitrogen loading rates during that period. Low water temperatures and generally less favorable conditions for phytoplankton growth decreased rates of nitrogen assimilation in the winter and ammonia, nitrite, and nitrate accumulated. Soluble reactive phosphorus concentrations were low throughout the year because physico‐chemical processes, such as precipitation and adsorption to bottom muds acted to continually remove inorganic phosphorus from the water column.

Seasonal and long-term changes in surface cover of aquatic plants in a shallow pond, Ojaga-ike, Chiba, Japan

Seasonal changes in surface cover and long-term floral changes in aquatic plants of a shallow eutrophic pond, Ojaga-ike, as well as the phenology of each species, were studied. Out of ten floating-leaved and submerged plants, the following five species showed a change in surface cover during 1978: Potamogeton crispus and Elodea nuttallii occupied 53.5% of the total pond surface in May, Trapa natans and Nelumbo nucifera 79.1% in July, N. nucifera and Hydrilla verticillata 62.0% in September and N. nucifera 41.2% in November. In addition to dramatic seasonal changes in surface cover, long-term floral changes occurred in this pond from 1971 onwards. While Nymphoides indica, Myriophyllum spicatum and H. verticillata decreased in number and in distribution ranges between 1971 and 1978, two newly established plants, N. nucifera and E. nuttallii, have now become dominant. The alteration in dominance may be due to water level fluctuations and interspecific competition for light. Seasonal changes in water quality during the study period are also summarized.