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.

土壤有机碳和氮的分布及其对气候变化的响应

碳、氮不仅是生物体必需的营养元素，也是重要的生态元素。大气中温室气体C02、N2O等浓度的增加使得碳、氮的生物地球化学循环及其温室气体的减缓排放措施研究成为全球变化研究中的热点问题。 土壤是陆地生态系统的核心，是连接大气圈、水圈、生物圈、岩石圈的纽带;它是陆生生物赖以生存的物质基础，是陆地生态系统中物质与能量交换的重要场所，其在全球碳、氮循环中起着十分重要的作用。一方面，土壤有机碳和氮的含量与分布直接关系到生态系统的生产力和生态系统的规模，同时土壤有机碳和氮的转化与迁移又直接影响到温室气体的组成与含量。而土壤本身又是生态系统中生物与环境相互作用的产物。因此，研究土壤有机碳和氮的分布、转化及其对全球变化的响应对于正确理解碳、氮的生物地球化学循环及其对全球变化的响应制定应对策略具有重要意义。 全球变化的陆地样带是从机理上理解陆地生态系统对全球变化的响应，预测全球变化对陆地生态系统的可能影响，实现预警、调节和减少全球变化不良影响，科学地规划和管理陆地生态系统的有效平台。目前，国际地圈一生物圈计划(IGBP)基于不同地区全球变化驱动因素的不同以及全球变化的潜在反馈作用强度的不同，在全球4个关键地区共启动了15条IG8P陆地样带。以水分为主要驱动力的中国东北样带(NECT：Northeast China Transect)即为IGBP的陆地样带之一。 本文以中国东北样带为平台，基于2001年对中国东北样带科学考察所采土壤样品的实测结果和气候资料分析了土壤有机碳和氮的梯度分布及其与土壤、气候等因子之间的关系;借助C02浓度升高和不同土壤湿度的模拟试验探讨了土壤有机碳和氮对气候变化的响应;根据作物残体还田的长期定位试验和盆栽试验研究了作物残体还田对土壤有机碳和氮转化的影响，讨论了农田生态系统通过作物残体还田对减缓温室气体排放的效应。主要结果和结论如下： (1).样带表层土壤有机碳平均为22.3土4.93 g．kg-1，下层土壤有机碳平均为8.9±1.20 g．kg-1。样带表层土壤活性有机碳平均为3.52±0.881 g.kg-1，占表层土壤有机碳的13.1±0.78%;下层土壤活性有机碳平均为1.14±0.250g.kg-l，占下层土壤有机碳的10.9±0.79%。样带土壤活性有机碳与土壤有机碳之间呈极显著正相关关系(相关系数r=0.993，P<0.001)。 (2).不同生态类型土壤有机碳和活性有机碳含量不同。中国东北样带东部(经度126°～131°)为温带针阔混交林山地，植被种类极其丰富，地带性土壤为暗棕壤，并且多为自然土壤，土壤有机碳和活性有机碳含量较高。但由于采样区局部地理环境、植被结构及人类干扰程度的不同，土壤有机碳和活性有机碳含量变异较大，平均为61.9±13.84 g．kg-1和10. 88±2.236g. kg-1。样带中部（经度119°～126°）为松辽平原栎林草原、农田区和大兴安岭山地草甸草原区，属半湿润向半干旱过渡的气候。该区域主要土壤类型为黑土、黑钙土、盐化或碱化草甸土及风沙土，土壤沙化、碱化严重，土壤有机碳和活性有机碳含量明显降低，平均为10.5±1.97 g．kg-l和1. 35±0.327 g．kg-1。样带中西部（经度113°～119°）为内蒙古高原草甸草原和典型草原区域，具有典型的半干旱气候特征。该区地带性土壤为栗钙土，局部丘陵区分布黑钙土，土壤有机碳和活性有机碳含量为14.6±1.65 g．kg-1和2.07±0.342g.kg-1。样带西部（经度111°～113°）为内蒙古高原荒漠草原区域，地带性土壤为棕钙土，土壤较为贫瘠，其有机碳和活性有机碳含量最低，平均为7.99±1.51 g．kg-1和0.51±0.216 g．kg-1。从总的趋势看，样带表层土壤有机碳和活性有机碳的梯度分布趋势一致，都呈现出随经度降低而下降的趋势，局部因土壤退化而出现波动。 (3).样带土壤有机碳和活性有机碳与土壤全量氮、磷、硫、锌及有效氮、磷、钾、锰、锌等均呈显著或极显著相关关系，与土壤PH、容重、持水量及孔隙度也呈显著或极显著相关关系。土壤表层有机碳和活性有机碳与降水量之间具有正的相关关系，其相关系数为r=0.677（P<0.001）和r=0.712（P<0.001）。但下层土壤有机碳和活性有机碳与降水量之间没有显著的相关关系。 (4).样带下层土壤有机碳和活性有机碳与经度之间仍具有显著的相关关系（r=0.454，P=0.026; r=0.473，P=0.020）。样带下层土壤有机碳和活性有机碳的变异小于表层。不同的生态系统，下层土壤有机碳和活性有机碳与表层土壤有机碳和活性有机碳的比率不同。总的来看，土壤活性有机碳含量随深度的增加而下降的幅度大于土壤有机碳。 (5).短期培养条件下，CO2浓度升高及干旱胁迫下，土壤有机碳的变化不大，其变异系数为1.28%;相比较之下，土壤活性有机碳对气候变化比较敏感，其变异系数为29.67%。不同土壤湿度，土壤活性有机碳含量发生变异的幅度因CO2浓度升高而降低。 (6).样带土壤全氮和有效氮与经度呈极显著正相关，其相关系数分别是r=0.695 (P<0.001)和0.636(P<0.001)。土壤表层全氮和有效氮的梯度分布与土壤有机碳的分布基本一致：沿经度呈现东高西低的趋势，局部由于土壤退化而出现低谷。样带除东部山区外，其它各部分土壤有效氮都很低，成为其植被生长的限制因子之一。样带下层土壤全氮和有效氮的含量低于表层，但样带不同部位下层土壤全氮和有效氮下降的幅度不同。总的来看，土壤全氮的剖面分布和土壤有机碳相似，而土壤有效氮则有所不同。 (7).土壤全氮和有效氮是土壤生化环境中两个重要的因子。样带土壤全氮和有效氮和土壤有机碳、全磷、全硫、全锌、土壤活性碳、有效磷、有效钾、有效锰、有效锌、土壤容重、田间持水量土壤总孔度等因子均呈显著或极显著的相关关系。 (8).样带表层土壤全氮和有效氮与降雨量之间呈极显著的正相关关系，相关系数分别是0.682(P<0.001)和0.688(P<0.001)。而下层土壤全氮和有效氮与降雨量之间的没有显著的相关关系（r=0.241，P=0.256; r=0.366，P=0.079）。土壤有效氮占全氮的比例与年均温呈显著正相关关系（相关系数r=0.390，p=0.044）。 (9).短期培养试验中，CO2浓度加倍和不同土壤湿度对土壤全氮和有效氮的影响没有达到显著水平。整个试验中土壤全氮和有效氮的变异较小（变异系数分别是5.55%和3.84%），但仍能反映一定的变化趋势。 (10)．玉米残体还田能够增加土壤氮素含量，减轻因其作为燃烧材料而造成的氮素损失和对大气的污染;玉米残体施入土壤，增加了土壤微生物氮含量，提高土壤氮活性，有利于土壤氮素养分的协调供应;玉米残体还田能够促进氮素从营养器官向籽粒中转移，提高氮素养分的利用效率。同时，玉米残体还田可以降低土壤NO3--N的累 积，减少肥料氮的损失4.7～5.6%。 (ll)．根据国内外文献和我们连续10年作物残体还田的肥料长期定位试验及盆栽试验结果，从减缓CO2排放、增加土壤碳固存、提高土壤生产力入手，分析了农业生态系统作物残体还田的必要性与可行性，讨论了农田作物残体还田，增加土壤碳固存对于减缓CO2排放、提高土壤生产力的作用与意义。提倡作物残体因地制宜地归还土壤，但作物残体还田后土壤固存与减缓温室气体排放的潜力还需要进一步进行研究。

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.