Microplastic accumulation in deep-sea sediments from the Rockall Trough.

the International Atomic Energy Agency CRP on “The assessment of soil erosion through the use of Cs-137 and related techniques as a basis for soil conservation, sustainable agricultural production, and environmental quality” (D1.50.05) and the IAEA CRP on “Soil erosion and sediment assessment studies by environmental radionuclid es and their applications to soil conservati on measures” (F3.10.01).

Bibliography of publications of 137 cesium studies related to erosion and sediment deposition

Acid volatile sulfide (AVS) is a natural agent in sediments which complexes some cationic metals and thereby influences the toxicity of these metals to benthic organisms. Because of its influence on metal bioavailability, AVS has been proposed as a key normalization phase for the development of sediment quality criteria for metals. However, studies conducted primarily in marine and estuarine systems have shown that AVS concentrations can vary markedly both temporally and with (sediment) depth. In this study, AVS concentrations were measured monthly for 16 mo in several segments of sediment cores from three freshwater lakes: Caribou Lake, Fish Lake and Pike Lake in northeastern Minnesota, USA. The concentrations of AVS in cores from the three lakes varied inversely with sediment depth. AVS concentrations also varied seasonally by as much as two orders of magnitude and were directly correlated with changes in water temperature. The correlation between AVS and temperature likely was related both to changes in primary productivity and sediment microbial activity.

Seasonal variation of acid volatile sulfide concentration in sediment cores from three northeastern Minnesota lakes

Abstract The varved marine anoxic sediment in the deep centre of the Santa Barbara Basin off California has been studied extensively by sedimentologists, micropalaeontologists and geochemists during the past four decades. The Santa Barbara Basin is the only basin in the California Borderland Province that exhibits laminations for most of the Holocene. These sediments are essential to further our understanding of climate in that they provide a rare oceanic record of climate change with high resolution. In this overview of the complex and multidisciplinary Santa Barbara Basin sediment research, we briefly introduce the reader to the various analytical approaches and present a comprehensive collection of literature references.

Tales of 1001 varves: a review of Santa Barbara Basin sediment studies

We used subfossil Chaoborus mandibles preserved in sediments of Cabin, Caledonia, and Celestine lakes, Alberta, to determine whether fish were present in the lakes (which now contain rainbow trout (Oncorhynchus mykiss) and lake chub (Couesius plumbeus)) prior to the first fish stockings early this century. We first tested whether Chaoborus were good indicators of the presence of fish in montane lakes in a survey of 43 lakes in jasper and Banff national parks. Chaoborus americanus was the only species inhabiting fishless lakes and was also found in three lakes with low fish density (co-occurring with C. flavicans in two of the three lakes). Other lakes containing fish had either C. flavicans or no Chaoborus species. Subfossils revealed that C. americanus was the predominant species prior to this century in Cabin and Celestine lakes, suggesting that these lakes were originally fishless; C. americanus (and C. trivittatus in Cabin Lake) were eliminated early this century, contemporarily with the first recorde...

Historical status of fish populations in Canadian Rocky Mountain lakes inferred from subfossil Chaoborus (Diptera: Chaoboridae) mandibles

Gravity coring of soft sediments can result in smearing of sediment between adjacent vertical sections in a core. We have quantified this artifact in a laboratory experiment with soft, highly porous gyttja using radiotracers to label the surface of the sediments. After coring, extrusion, and sectioning, the radiotracers were measured down to 5 cm in inner core sections and to 10 cm in outer core sections. We have estimated the impact of smearing on the interpretation of concentration-depth profiles, and gradients calculated from smeared profiles can be less than those occurring in situ in the sediments. This effect seems most pronounced near the mud— water interface. We have simulated radionuclide profiles in sediments from Chernobyl fallout (e.g. 134Cs) and natural emissions (e.g. 210Pb) to examine this problem. Concentration gradients of these radionuclides and of other contaminants used to establish geochronologies can be altered significantly depending on sediment type. A tracer layered on the surface of the sediments can be used to quantitate smearing effects, and corrections can then be made to concentration-depth profiles.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1991.36.7.1492

R. J. Cornett

Papers

Smearing of gravity core profiles in soft sediments