西藏拉果错卤虫：2营养成分

卤虫包括成体,无节幼体和卤虫卵,蛋白质,氨基酸,脂肪酶等营养成分的含量是评价卤虫质量的主要标准,因为摄食动物饵粒效果取决于氨基酸,脂肪酸的组成与含量,西藏拉果错卤虫的营养成分含量较高,１９９６、１９９７年盐湖研究中心连续取样测定,其蛋白质含量成本接近２０％,无节幼体约５５％,脱壳卵近５０％;粗脂肪成体３％,无节幼 和脱壳超过８７％,三种高级不饱和脂肪酸（２０：３,２０：４,２０：５）ＨＵＦＡ含量。     

Anthropogenic nutrient load of the Baltic Sea

The discharge of nutrients is investigated in relation to their sources and effects in two case studies. The reduction of 47% in the phosphorus load from Denmark to marine areas between 1989 and 1993 has resulted in significantly lower phosphorus concentrations in most Danish coastal waters, and tendency to decrease can be seen in the Belt Sea and Kattegat as well. No general changes in nitrogen concentrations have been observed. This is due to the fact that more than 80% of the nitrogen load in Danish waters originate from diffuse agricultural sources.In the Pomeranian Bight strong nutrient gradients are generated by the mixing of Odra river water and coastal water. The spreading of the river plume could be exactly observed especially in winter, when biological activity is low. In general, different types of distribution, transport and modification patterns can be described.The annual input of nutrients from the catchment area to the Baltic Sea was estimated to be around 1000 kt N and 46 kt P. As a result, winter concentrations of phosphate and nitrate are characterized by positive overall trends in the surface layer in all subregions of the Baltic Proper for the period 1969 to 1993. These trends stem mainly from the strong increase in the 1970ies and early 1980ies. Thereafter, the concentrations of both nutrients fluctuate strongly around a high level. The drastic decrease in fertilizer consumption since the late 1980ies mainly caused by the great economic changes in the countries of the former East Bloc is not yet significantly reflected in decreasing winter concentrations, but first signs already have been found in the decrease in averaged phosphate concentrations in winter, especially in the Arkona and Bornholm Seas.     

Water quality and spatio-temporal hot spots in an effluent-dominated urban river

In arid and semi-arid regions, many rivers experience extremely low flow conditions during seasonal dry periods. During these times, effluent from wastewater treatment plants can make up the majority of flow in the river. However, water quality in urban systems can also be strongly influenced by the natural or human-influenced flow regime and discharge from other anthropogenic sources such as industrial operations and runoff from impervious surfaces. In this study, we aimed to determine whether water quality was controlled primarily by wastewater discharge in an effluent-dominated river. Between May 2016–May 2019, we systematically measured water temperature, pH, dissolved oxygen, biochemical oxygen demand, and the concentrations of nitrate-N, ammonia-N, and orthophosphate in the South Platte River in the Denver metropolitan area, Colorado, USA. We found that, despite being an effluent-dominated river, wastewater treatment plant discharge was not the principal factor controlling water quality in many of the sampled areas. Non-point source pollution from impervious surfaces, delivered to the river through storm drains and minor tributary streams, also contributed to the high nutrient conditions in several locations. We also noted a strong seasonality in water quality, with higher concentrations of nutrients and higher biochemical oxygen demand in the winter months when wastewater effluent can make up more than 90% of the flow in the river. Thus, the interaction of discharge location and reduced seasonal flow produced spatio-temporal hot spots of diminished water quality. More stringent enforcement of water quality regulations may improve water quality in this system. However, a large portion of the pollution seems to be from non-point sources, which are very difficult to control.     

Effects of lakes and reservoirs on annual river nitrogen,phosphorus, and sediment export in agricultural and forested landscapes

Recently, effects of lakes and reservoirs on river nutrient export have been incorporated into landscape biogeochemical models. Because annual export varies with precipitation, there is a need to examine the biogeochemical role of lakes and reservoirs over time frames that incorporate interannual variability in precipitation. We examined long‐term (~20 years) time series of river export (annual mass yield, Y, and flow‐weighted mean annual concentration, C) for total nitrogen (TN), total phosphorus (TP), and total suspended sediment (TSS) from 54 catchments in Wisconsin, USA. Catchments were classified as small agricultural, large agricultural, and forested by use of a cluster analysis, and these varied in lentic coverage (percentage of catchment lake or reservoir water that was connected to river network). Mean annual export and interannual variability (CV) of export (for both Y and C) were higher in agricultural catchments relative to forested catchments for TP, TN, and TSS. In both agricultural and forested settings, mean and maximum annual TN yields were lower in the presence of lakes and reservoirs, suggesting lentic denitrification or N burial. There was also evidence of long‐term lentic TP and TSS retention, especially when viewed in terms of maximum annual yield, suggesting sedimentation during high loading years. Lentic catchments had lower interannual variability in export. For TP and TSS, interannual variability in mass yield was often >50% higher than interannual variability in water yield, whereas TN variability more closely followed water (discharge) variability. Our results indicate that long‐term mass export through rivers depends on interacting terrestrial, aquatic, and meteorological factors in which the presence of lakes and reservoirs can reduce the magnitude of export, stabilize interannual variability in export, as well as introduce export time lags. Copyright © 2013 John Wiley & Sons, Ltd.     

Solutes in overland flow following fire in eucalyptus and pine forests,northern Portugal

Small bounded plots were used to investigate dissolved nutrient losses in overland flow in eucalyptus and pine forests in northern Portugal following understorey fires. Losses of NON, POCa²⁺, Mg²⁺ and K⁺ were measured over 19 months during the first 2–3 years after fire. Solute losses in overland flow increased after fire in eucalyptus and pine terrain due to the mineralization of litter and vegetation and increased overland flow. The data suggest that (i) elevated losses persist for at least 2 and 3 years at the pine and eucalyptus sites respectively and (ii) soluble losses of POK⁺ in a post‐fire cycle may exceed those adsorbed to eroded material. Losses of POalthough relatively small, are potentially the most detrimental to soil fertility and forest productivity because of the limited opportunity for P replenishment and correspondingly high P losses adsorbed to eroded sediment. Copyright © 2000 John Wiley & Sons, Ltd.     

氮、磷等营养物质对低洼盐碱地鱼塘水质的影响

通过在实验围隔中添加不同浓度的氮、磷等营养物质,对黄淮海平原低洼盐碱地鱼塘中的水质变化情况进行了初步研究,结果表明：1）围隔水体中异养细菌数量的变动,与水体中氮、磷等营养物质的浓度及比例密切相关,尤其是水体中磷的浓度对异养细菌数量的影响更为显著。2）围隔水体中的氮、磷等营养浓度及比率,明显地影响着其中藻类的数量和生物量。在实验条件下,水体中磷对藻类生长的影响要大于氮对藻类生长的影响,水体中N：P比为10：1左右是比较适宜藻类生长的比例。3）围隔水体中氮、磷等营养盐的去除能力与其中藻类的生物量及水体中N：P的比率密切相关,当围隔水体中的N：P比为10：1左右时,围隔水体中的藻类生长最好,生物量增加最快,相应地其对TN、TP的去除率也是最高的。     

中国南极长城湾及附近海区1993/1994年度夏季表层水样无机氮、磷酸盐的浓度及其分布状况(英)

The concentrations and distributions of four species of inorganic nutrient salts in surface sea water of Chinese Great Wall Bay and its adjacent sea area, Antarctica were surveyed during austral summers of 1993～1994.The results obtained are as follows:The general concentrations of NH4-N, NO3-N, NO2-N and PO4-P are 2. 13, 7. 07, 0. 74 and 1. 12 μg. din-3, respectively. Generally speaking, the concentrations are higher inside the Bay than those　 outside and the higher values of those inorganic salts often appear in December. The time for the station　where their higher and lower concentrations appear are not completely the same. The descending order　of the magnitudes of ΣN/P value according to the arrangement monthly is: Dec. Feb. Jan.. The　 variations of water temperature are mostly consist with the concentrations of NH4-N, PO4-P and ΣN/P, but not often with NO2-N. The low concentrations of nutrient salts as shown in some stations may be related with absorption by phytoplankton, perhaps including autotrophic bacteria.The results suggest that the area surveyed has a typical characteristic of an inner shallow water bay, sub-Antarctica. The nutrients needed for phytoplankton are sufficient, and the Bay surveyed is still in a normal condition.     

青藏铁路沿线高寒草甸植物群落特征对人为干扰梯度的响应——以风火山高山嵩草草甸为例

选择风火山地区受到人为干扰的高寒草甸,对处于不同干扰梯度的高寒草甸植物群落,用样带法进行调查.共调查5条样带,50个样方.统计植物的科属组成,计测其群落盖度、频度指标以及物种丰富度指数、多样性指数及均匀度指数等.对不同干扰梯度上的植物群落结构及其物种组成特点进行分析,结果表明:青藏铁路沿线的高寒草甸随着人为干扰的强度的增加,植物群落的科、属、种组成趋向单一;群落中起显著作用的物种趋向是高山嵩草→高山嵩草和矮嵩草→早熟禾和扇穗茅→早熟禾→羊茅和早熟禾;按照植物种群的重要值对干扰梯度的响应,该地区植物种群可被划分为3类响应模式,即忍耐型种、敏感型种和扩展型种.随着干扰强度的增加,物种丰富度指数和物种多样性随着干扰增加而降低.干扰梯度与有机质含量、全氮、水解氮、全磷、速效磷均呈显著相关,但是与全钾和速效钾相关关系不明显.