Retention and fate of experimentally added mercury in a Massachusetts salt marsh treated with sewage sludge

A simple, rapid, precise and reproducible procedure is described for sample preparation, extraction and measurement of total mercury in peaty sediments, plants and animal tissues. Various amounts of a heavy metal containing dried sewage sludge were applied to experimental plots in a New England salt marsh. This treatment resulted in elevation of mercury levels in the surface 5 cm of the soil. Discrepancies in the bulk density of marsh sediments corresponded with interparticle spaces and detritus/mineral ratios in the peat matrix. Mass balance calculations showed that wetlands covered with tall Spartina alterniflora lost mercury considerable faster than higher marsh locations which retained virtually all mercury added. The shortest halflife of mercury calculated was four years. Grain size analyses of peat and sewage sludge suggested that mercury in the higher intertidal range remained associated with sludge components. Biochemical and physical processes affecting the dissipation of mercury from creek side sediments are discussed.     

Bottom foraminiferal assemblages in the Deryugin Basin (Sea of Okhotsk) during the past 26000 years

Benthic foraminifers from a core of bottom sediments obtained in the Deryugin Basin at a depth of 1750 m were examined. Three distinct benthic foraminiferal assemblages that replaced one another throughout the last 26000 years were recognized. The assemblage dominated by Alabaminella weddellensis, Uvigerina auberiana, and Cassidulina translucens dwelled here from 26 to 24 ky B.P. The sediments of the glacial period between 26 and 12.18 ky B.P. contain no benthic foraminifers. The composition of the sediments suggests the existence of active bottom vents of gas-bearing fluids during that time. The dominance of Brizalina spissa, Uvigerina peregrina, and Cassidulina laevigata is characteristic of the period from 12.18 to 7 ky B.P., when the productivity of the surface waters in the region was high, and warm, poorly oxygenated waters spread over the bottom of the basin. During the past 7 000 years, the bottom conditions in the sea were similar to the present-day conditions and an assemblage with the dominance of Gyroidina orbicularis, Uvigerina auberiana, and Cassidulina teretis developed in the region.     

Influence of Current Width Variation on the Annual Mean Transport of the East Sakhalin Current: A Simple Model

Recent observations suggest that the annual mean southward transport of the East Sakhalin Current (ESC) is significantly larger than the annual mean Sverdrup transport. Motivated by this observational result, transport of a western boundary current has been investigated using a simple numerical model with a western slope. This transport is defined as the instantaneous barotropic transport integrated from the western boundary to the offshore point where the barotropic velocity vanishes. The model, forced by seasonally varying wind stress, exhibits an annual mean of the western boundary current transport that is larger than that of the Sverdrup transport, as observed. The southward transport from October to March in the model nearly equals the instantaneous Sverdrup transport, while the southward transport from April to September decreases slowly. Although the Sverdrup transport in July vanishes, the southward transport in summer nearly maintains the annual mean Sverdrup transport, because the barotropic Rossby wave cannot intrude on the western slope. This summer transport causes the larger annual mean. Although there are some uncertainties in the estimation of the Sverdrup transport in the Sea of Okhotsk, the seasonal variation of the southward transport in the model is qualitatively similar to the observations.     

A numerical experiment on the calculation of the tropical Atlantic circulation in 1982–1983, with the real wind considered

This paper discusses the results obtained through numerical modelling of the annual course of circulation and thermohaline field evolution in the tropical Atlantic under the impact of real wind forcing (from March 1982 to March 1983) and compares them with the calculation of seasonal variability induced by the climatic wind. Changes in the pattern of the equatorial currents and related temperature fields induced by the specific peculiarities in the wind field are analysed.Translated by Vladimir A. Puchkin.     

A sample changer for automated seawater nutrient analysis systems

An automatic sample changer based upon a commercially available 20-port rotary valve has been developed for use in automated seawater nutrient analyses. All parts exposed to seawater are of stainless steel, Teflon®, or Kel-F®. The sampler has proven to be rugged and efficient in both shore and shipboard laboratories.     

Observation of clouds and solar radiation over the Pacific Ocean as relation to global climate

ＯｂｓｅｒｖａｔｉｏｎｏｆｃｌｏｕｄｓａｎｄｓｏｌａｒｒａｄｉａｔｉｏｎｏｖｅｒｔｈｅＰａｃｉｆｉｃＯｃｅａｎａｓｒｅｌａｔｉｏｎｔｏｇｌｏｂａｌｃｌｉｍａｔｅ￥ＦａｒｎＰａｒｕｎｇｏ；ＣｌａｒｅｎｃｅＮａｇａｍｏｔｏ；ＣｅｃｉｌｉａＭ．Ｉ．Ｒ．Ｇｉ...     

Quaternary geology of the Amazonian Lowland

The Quaternary history of the Amazon lowlands is characterized by deposition of sediments of Andean provenance and by the influences of changing sea levels. Areas well above the present water tables were not reached by Pleistocene high-water stages. These areas have been intensively weathered since the Tertiary, forming hard lateritic weathering horizons. These weathering horizons are best explained by the relatively constant, humid tropical climate throughout the Quaternary. In the western Amazonian Lowland, flood plains corresponding to the different Pleistocene sea-level heights were formed. During low sea level, erosion in the drainage areas increased and the water levels of the central Amazon River system were lowered. Valleys drowned and lakes formed in the lower reaches of rivers and creeks during high sea-level stages. These lakes (ria lakes) remained in the valleys with rivers having a low sediment load. Seismic profiling (3.5 kHz) in some of these lakes clearly showed deposits of the three last periods of Quaternary high sea-level stages.     

Paleoenvironment and sea-level change in the early Cretaceous Barents Sea—implications from near-shore marine sapropels

The late Volgian (early "Boreal" Berriasian) sapropels of the Hekkingen Formation of the central Barents Sea show total organic carbon (TOC) contents from 3 to 36 wt%. The relationship between TOC content and sedimentation rate (SR), and the high Mo/Al ratios indicate deposition under oxygen-free bottom-water conditions, and suggest that preservation under anoxic conditions has largely contributed to the high accumulation of organic carbon. Hydrogen index values obtained from Rock-Eval pyrolysis are exceptionally high, and the organic matter is characterized by well-preserved type II kerogen. However, the occurrence of spores, freshwater algae, coal fragments, and charred land-plant remains strongly suggests proximity to land. Short-term oscillations, probably reflecting Milankovitch-type cyclicity, are superimposed on the long-term trend of constantly changing depositional conditions during most of the late Volgian. Progressively smaller amounts of terrestrial organic matter and larger amounts of marine organic matter upwards in the core section may have been caused by a continuous sea-level rise.     

赤潮生物种类特征光谱获取技术

较为系统地研究了赤潮生物水体反射率曲线获取方法。通过对 2类反射率反演方法得出的反射率曲线与实际反射率曲线进行比较 ,得出在不具备大气环境参数的情况下 ,经验线性法的反演结果与实际反射率曲线最接近的结论 ,并进一步对正常海水和赤潮生物水体的光谱特性进行分析 ,提取出赤潮生物水体的特征光谱。这是进行赤潮监测和识别的重要前提     

Numerical calculation for the flow of submerged bodies under a free surface

The flow field generated by a Rankine body moving under a free surface in afinite-depth water is calculated by potential theory. Velocity field generated by a source located at the origin is calculated first by using highly efficient and adaptive quadratures of the QUADPACK library. This solution is used for generating the flow around a Rankine body by locating a source and an equal strength sink along the body axis. Results agree well with the existing literature.