Distribution of persistent organic contaminants in canyons and on the continental shelf off central California

The National Status and Trends (NS&T) Program has conducted studies to determine the spatial extent and severity of chemical contamination and associated adverse biological effects in coastal bays and estuaries of the United States since 1991. Sediment contamination in U.S. coastal areas is a major environmental issue because of its potential toxic effects on biological resources and often, indirectly, on human health. Thus, characterizing and delineating areas of sediment contamination and toxicity and demonstrating their effect(s) on benthic living resources are therefore important goals of coastal resource management at NOAA. The National Centers for Coastal Ocean Science, and the Office of National Marine Sanctuaries, in cooperation with the U.S. Geological Survey (USGS), University of California Moss Landing Marine Lab (MLML), and the Monterey Bay Aquarium Research Institute (MBARI), conducted ecosystem monitoring and characterization studies within and between marine sanctuaries along the California coast in 2002 and 2004 on the NOAA RV McArthur. One of the objectives was to perform a systematic assessment of the chemical and physical habitats and associated biological communities in soft bottom habitats on the continental shelf and slope in the central California region. This report addresses the magnitude and extent of chemical contamination, and contaminant transport patterns in the region. Ongoing studies of the benthic community are in progress and will be reported in an integrated assessment of habitat quality and the parameters that govern natural resource distributions on the continental margin and in canyons in the region.

Coastal climate reflected in carbon-13/carbon-12 ratio of organic carbon in varved sediment from Santa Barbara basin

A 1844-1987 time-series of carbon stable isotope ratios from dated sedimentary total organic carbon from the center of the Santa Barbara basin is compared with historical climate and oceanographic records. Carbon derived from carbon-13-depleted phytoplankton and carbon-13-enriched kelp appear responsible for a large part of the isotopic variance in sedimentary total organic carbon. El Niño/Southern Oscillation events are recorded by the isotopic response of marine organic carbon in sediments.

Geochemical evidence for enhanced upwelling and organic productivity during the late Quaternary on the continental margin of northern California

EXTRACT (SEE PDF FOR FULL ABSTRACT): Laminated sediments are preserved in upper Pleistocene sections of cores collected on the continental slope at water depths within the present oxygen-minimum zone from at least as far north as the Klamath River and as far south as Point Sur. Comparison of sediment components in the laminae with those delivered to sediment traps as pelagic marine "snow" show the dark/light lamination couplets are indeed annual (varves). ... The presence of carbon-, sulfur-, and metal-rich sediments, as well as lack of bioturbation, all support the theory that the oxygen-minimum zone in the northeastern Pacific Ocean was more intense - in fact, anoxic - during the late Pleistocene in response to greater coastal upwelling and higher organic productivity.

Toxicity of some organic biocides to exotic carp fingerlings Hypophthalmichthys molitrix (C and V)

A bioassay study was conducted using three organic pesticides to determine their comparative toxicity to fingerlings of Hypophthalmichthys molitrix. There was wide variation in the toxicity of different pesticides with 24 hr LC sub(50) values ranging from 0.000403 to 0.294 mg/l. Endosulfan appeared to be the most toxic, whereas BHC was the least.

Culture of Moina micrura on various organic waste products

Moina micrura, a cladoceran species, is considered to be one of the best live food organisms for rearing the young larval stages of fish and prawn. Considering the importance of this species in hatchery operations the present study was undertaken to record its fecundity and life span and to culture it using different locally available organic waste products. In indoor culture, a maximum production of 2600 ind/1 and a minimum of 1050 ind/1 were obtained when treated with gram + maize oilcake and "till" oilcake respectively. In outdoor culture, a highest production of 6000 ind/1 was achieved with "Alsi" and "till" oilcakes and a lowest density of 1050 ind/1 with coconut oilcake and raw cattle dung was obtained with an inoculation rate of 5 ind/1.

Organic carbon in the sediments of the lower reaches of Periar River

Sediments are indicators of the quality of water overlying them and hence, useful in the assessment of environmental pollution. Temporal and spatial variations in sediment characteristics and organic carbon content from 9 stations in the lower reaches of Periyar River an area in Cochin Backwater, India which is polluted from different sources were studied for one year during 1981. Variations in colour and texture of sediments were brought about by changes in the grain size and state of oxidation of organic matter. The colour of the sediment varied from greyish black at stations 1 and 2, brownish at station 3, black at stations 4 to 8 and reddish at station 9. Organic carbon and sediment texture showed a direct relationship at all stations except at station 9 where organic carbon content showed an irregular pattern. Overall range of organic carbon content was between 1.19 and 29.6 mg.g super(-1). The mean organic carbon of the stations ranged between 6.8 mg.g super(-1) (station 5) and 20.8 mg.g super(-1) (station 9). On the whole temporal variations were considerable with high values at station 9 and low values at station 5. Fluctuations were more at stations 6, 7 and 8.

氮素添加对内蒙古羊草草原净氮矿化的影响

　　氮素作为陆地生态系统生产力主要的限制因子，对生态系统过程的调控有着重要的意义。净氮矿化是有机氮素到无机氮素的转变过程，该过程决定了土壤氮素的可利用性。准确估计土壤的供氮能力可以为确定最佳施肥量和施肥时间提供理论依据，并将影响着土地的可持续发展和管理政策。氮矿化潜力N0被定义为在最适温度和湿度下，土壤氮素在无限时间内所能矿化的最大量。由于氮矿化潜力是土壤供氮能力很好的指示值，所以对氮矿化潜力的研究能够使我们更好地了解土壤的氮素矿化动态和其供氮潜力。 　　为更好地了解天然草原氮素矿化对全球氮沉降背景以及草原施肥管理模式的响应，我们从2000年起在内蒙古羊草草原开展了长期的氮素添加实验，分别设置对照(N0)、添加5g N•m-2(N1.75)、30g N•m-2(N10.5)和80g N•m-2(N28)四个氮肥添加梯度以及对照(control)、添加100g有机肥•m-2(O100)、添加500g有机肥•m-2(O500)、添加1000g有机肥•m-2(O1000)四个有机肥添加梯度。氮肥添加在相邻并同时进行施肥的两个生态系统类型中展开，即成熟羊草草原（A区，1979年围封）和退化的羊草草原（B区，1999年围封），有机肥添加也同时在与之相邻的C区中展开（C区的土地利用历史与B区一致）。 2002年和2006年，从A、B区中进行氮肥处理后的土壤取样；有机肥处理的土壤样品从2002年C区中获得。土样在最佳温度(25℃)和湿度(60%田间持水量（WHC）)下进行了5周室内培养，并用阶段淋溶方法来测定氮肥添加和有机肥添加对土壤氮矿化动态的影响。 　　氮肥添加显著降低了土壤的pH值，但累积氮矿化量与土壤pH值、有机碳、全氮均没有显著的相关性。在两个区内，氮素添加都显著改变了土壤的累积氮矿化量。最高氮素处理N28相对应于最低的累积氮矿化量，而低氮素处理N1.75却使得累积氮矿化量最高。同时，在N0和N1.75处理中硝态氮的含量高于铵态氮，但在N28处理中却表现出相反趋势。实验还表明大多数氮素添加强度处理在A区比B区有更高的土壤累积氮矿化量。 　　有机肥添加也显著改变了土壤5周内的累积氮矿化量，并且累积氮矿化量随有机肥添加强度的升高而显著增加。培养5周末时土壤的累积铵态氮的含量与有机肥施加强度之间并没有相关性，但是累积硝态氮的含量有随着有机肥施加强度的上升而增加的趋势。 　　基于前5周土壤培养所得到的结果，我们选择了氮肥添加的N0，N1.75， N28处理以及有机肥添加的control、O100、O1000处理继续进行了长达15周的培养。培养数据与描述土壤氮矿化动态的一级动力学模型--first-order kinetics: Nm=N0（1－exp(-kt)）拟合良好( R2=0.893～0.97)。无论是氮肥添加还是有机肥添加都显著增加了土壤的氮矿化潜力N0，并且N0随着氮肥或者机肥添加强度的增加而增加。对于氮肥处理的土壤来说， N0与氮矿化速率常数k之间反向相关，但是在有机氮处理的土壤中N0与k之间却没有相关性。总的结果显示，经有机肥添加的土壤比经氮肥添加的土样有着更大的氮矿化潜力N0值以及氮矿化速率常数k值，较大的k值暗示着土壤氮素较快的周转速率。