Sediment record changing conditions

Data on weather conditions, especially temperature and rainfall (temporal distribution and intensity) in the study area are essential for the evaluation of the dissipation data. It is very important to understand the water balance in the paddy field as accurately as possible when calculating the rate of outflow. Records of changes in water temperature and sediment temperature are also helpful for modeling the behavior of a chemical in the rice paddy field. 

Departures from idealized redox zonation can also result from temporal shifts in sedimentation rates and in the depth of the oxic zone. Some examples are provided in the next section using iron and manganese as case studies. These elements are particularly useful as records of past changes in sedimentation rates because they respond to local redox conditions by undergoing postdepositional migration. 

Lateral transport of particles is an important component of modern biogeochemical cycles. Furthermore, lateral redistribution of sediments modifies the sedimentary record of past changes in environmental conditions. Therefore, paleoceano-graphic studies that rely on reconstructing accumulation rates of sedimentary constituents must account for lateral redistribution of sediments within the ocean. 

Palynology is the study of fossil pollen (and sometimes plant spores) extracted from lake sediment, peat bog, or other matrices. The most common goal of paly-nological research is to reconstruct the probable character of historical plant communities, inferred from the abundance of species in dated portions of the fossil pollen record. Pollen analysis is an extremely useful tool for understanding the character of ancient vegetation and its response to changes in environmental conditions, particularly in climate. Pollen analysis also has an economically important modem industrial use in the exploration for resources of fossil fnels. Palynology is also used to help reconstmct the probable habitats and foods of ancient humans and of wild animals. 

In 1993-1994, two saltwater inflow events caused a change from anoxic to oxic conditions in the deep and bottom water of the Gotland Basin. A further stagnation period established from 1995 until 2003, and permanent anoxic conditions below 150 m were recorded since 1999. Under this context, the change in the environmental conditions coupled with a lifting of the redoxcline was a major process that influenced the speciation of trace metals, the resulting change in their solubility in the water column, and their export to anoxic sediments. 

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