台风对工厂化虾池生态系中氮磷关系影响的研究

利用2003年7月台风发生期问对虾工厂化养成后期3个用日的实测数据，分析研究了该时期水环境中无机氮(DIN)、无机磷(DIP)的含量变化及其与环境因子的关系。结果表明：在该养殖生态系统中，台风气候对DIN，DIP的含量变化影响较大，尢以养成密度较大的养殖池最为明显，物理、生物、化学过程在不同周日均得到了良好体现；但无论养成密度大小，水环境中的N／P比值及浮游植物量均较高，说明该生态系中浮游植物对营养盐含量变化有较宽的适应范围。     

Temporal changes and spatial variation of soil oxygen consumption, nitrification and denitrification rates in a tidal salt marsh of the Lagoon of Venice, Italy

The aim of the present study was to investigate seasonal and spatial patterns of soil oxygen consumption, nitrification, denitrification and fluxes of dissolved inorganic nitrogen (DIN) in a tidal salt marsh of the Lagoon of Venice, Italy. In the salt marsh, intact soil cores including overlying water were collected monthly at high tide from April to October in salt marsh creeks and in areas covered by the dominant vegetation, Limonium serotinum. In May, cores were also collected in areas with vegetation dominated by Juncus maritimus and Halimione portulacoides. In laboratory incubations at in situ temperature in the dark, flux rates of oxygen and DIN were monitored in the overlying water of the intact cores. ¹⁵N-nitrate was added to the overlying water and nitrification and denitrification were measured using isotope-dilution and -pairing techniques. The results show that highest soil oxygen consumption coincided with the highest water temperature in June and July. The highest denitrification rates were recorded in spring and autumn coinciding with the highest nitrate concentrations. Soil oxygen consumption and nitrification rates differed between sampling sites, but denitrification rates were similar among the different vegetation types. The highest rates were recorded in areas covered with L. serotinum. Burrowing soil macrofauna enhanced oxygen consumption, nitrification and denitrification in April and May. The data presented in this study indicate high temporal as well as spatial variations in the flux of oxygen and DIN, and nitrogen transformations in the tidal salt marshes of the Venice lagoon during the growth season. The results identify the salt marshes of the Venice lagoon as being metabolically very active ecosystems with a high capacity to process nitrogen.     

北京市夏季低层大气NOx、O3垂直分布观测研究

根据 2 0 0 0年夏季在北京 32 5 m铁塔上的一次梯度观测实验 ,给出 8m,12 0 m和 2 80 m三层上的 NO、NO2 、O3 浓度的观测结果。对 NO,NO2 ,O3 小时平均浓度的日变化和垂直分布规律进行了分析 ,结果发现 :(1)各高度上的 NO,NO2 ,O3 浓度均有明显的日变化特征 ,阴雨天的日变化更加复杂 ;(2 ) O3 在晴朗白天有单、双及三峰型分布 ;(3)相对于 12 0 m和 2 80 m,近地面 8m处的 NO浓度最高 ,而 O3 浓度最低 ;(4) NO2 、O3 日平均浓度日变化振幅 12 0 m处最大 ;(5 )中午前后 NO,NO2 ,O3 浓度均在 12 0 m最高。     

Stable isotope compositions of organic carbon and nitrogen of two mangrove stands along the Tanzanian coastal zone

The stable isotopes of organic carbon (OC) and nitrogen, contents of OC and nitrogen for roots, bark, leaves, flowers and fruits of various mangrove species from Kisakasaka (Zanzibar) and Bagamoyo (mainland Tanzania) are used to assess (1) if some mangrove species are capable of fixing atmospheric nitrogen, (2) if there are differences between species in the same stand and in different stands and (3) if the mangrove signature is preserved in the sediments. Mean OC stable isotope results of various plant components range from −25.9‰ to −29.1‰ suggesting that mangrove trees in the two stands follow the C₃ type of photosynthetic pathway. Mean nitrogen isotope values for various plant components range from −1.5‰ to 3.2‰ suggesting atmospheric nitrogen fixation by mangrove plants, but δ¹⁵N values approaching −3‰ that are more negative than typical diazotroph biomass exclude this possibility. Mangrove species thriving further inland are enriched in ¹³C and ¹⁵N relative to those thriving near the shoreline owing to complete utilization of available nutrients.Sediments beneath the mangrove forest are characterized by lower C/N ratio values and enrichment in ¹³C and ¹⁵N relative to plant material owing to mixing of nitrogenous rich material from adjacent area. High concentration of OC is found in bark and roots, while high nitrogen concentration is found in fruits and flowers only.     

Canopy foliar nitrogen retrieved from airborne hyperspectral imagery by correcting for canopy structure effects

A statistical relationship between canopy mass-based foliar nitrogen concentration (%N) and canopy bidirectional reflectance factor (BRF) has been repeatedly demonstrated. However, the interaction between leaf properties and canopy structure confounds the estimation of foliar nitrogen. The canopy scattering coefficient (the ratio of BRF and the directional area scattering factor, DASF) has recently been suggested for estimating %N as it suppresses the canopy structural effects on BRF. However, estimation of %N using the scattering coefficient has not yet been investigated for longer spectral wavelengths (>855 nm). We retrieved the canopy scattering coefficient for wavelengths between 400 and 2500 nm from airborne hyperspectral imagery, and then applied a continuous wavelet analysis (CWA) to the scattering coefficient in order to estimate %N. Predictions of %N were also made using partial least squares regression (PLSR). We found that %N can be accurately retrieved using CWA (R² = 0.65, RMSE = 0.33) when four wavelet features are combined, with CWA yielding a more accurate estimation than PLSR (R² = 0.47, RMSE = 0.41). We also found that the wavelet features most sensitive to %N variation in the visible region relate to chlorophyll absorption, while wavelet features in the shortwave infrared regions relate to protein and dry matter absorption. Our results confirm that %N can be retrieved using the scattering coefficient after correcting for canopy structural effect. With the aid of high-fidelity airborne or upcoming space-borne hyperspectral imagery, large-scale foliar nitrogen maps can be generated to improve the modeling of ecosystem processes as well as ecosystem-climate feedbacks.     

冬季室温铁碳内电解质下4种水生植物及其组合的净化效果

为探究冬季室温不同铁碳内电解基质下4种水生植物及其组合对人工湿地污水的净化效果,通过构建小试试验装置来探究冬季室温铁碳内电解质下菖蒲、鸢尾、金鱼藻、狐尾藻4种水生植物及菖蒲+鸢尾、金鱼藻+狐尾藻、菖蒲+鸢尾+金鱼藻+狐尾藻3种组合在不同试验时间内对污水中COD、NH_3+-N、TN、TP 4种污染物的净化效果。结果表明:冬季室温不同铁碳内电解基质下,4种植物及其组合对COD、TN、TP去除效果均较好,无显著性差异。NH3+-N净化效果较好的是菖蒲组和金鱼藻+狐尾藻组合。研究发现,铁碳内电解基质在COD、TN、TP的去除过程中发挥了主要作用。在TN去除方面,铁碳内电解质与植物的组合效果比单纯内电解质对污水的净化效果好。4种植物及其组合在NH_3+-N去除方面均发挥了重要作用,且不同处理间存在显著差异。     

氮,磷,维生素和微量金属对赤潮生物海洋原甲藻的增殖效应

在室内培养实验中观测了赤潮生物海洋原甲藻ＰｒｏｒｏｃｅｎｔｒｕｍｍｉｃａｎｓＥｈｒｅｎｂ对ＮＯ、ＮＨ和甘氨酸的需求。结果表明，硝酸盐的浓度从４０到３００μｍｏｌ／ｄｍ３，氨盐浓度从５０到１５０μｍｏｌ／ｄｍ３，甘氨酸和谷氨酸混合液浓度从４０到８０μｍｏｌ／ｄｍ３皆能较好地维持海洋原甲藻的增殖。磷酸盐起着磷源作用。在ＥＤＴＡ浓度为８０μｍｏｌ／ｄｍ３的培养液中，Ｆｅ３＋的浓度从０，．５到１μｍｏｌ／ｄｍ３，Ｍｎ２＋从０到２０μｍｏｌ／ｄｍ３和Ｃｏ２＋从０．１到０．４μｍｏｌ／ｄｍ３能促使海洋原甲藻的增殖。维生素效应试验表明：维生素Ｂ１是生长促进因子，而维生素Ｂ１２和生物素在光和暗处皆未能促进海洋原甲藻的增殖。无机氮和磷的最小细胞额分别为０．７４×１０－１２ｍｏｌ／细胞和０．０４５×１０－１２ｍｏｌ／细胞，其中磷比氮更能限制海洋原甲藻的增殖。     

不同氮源对盐生杜氏藻生长和细胞生化组成的影响

研究3种氮源(NaNO3,尿素,NH4NO3/尿素复合肥)对盐生杜氏藻(Dunaliella salina OUN07)生长和细胞生化组成的影响.结果表明,D. salina OUN07生长最适的是0.75mmol/L尿素,最大细胞密度为105×104 cell/mL,对照组仅为59×104cell/mL;最高β-胡萝卜素含量110.6mg/g出现在0.125/0.125 mmol/L NH4NO3/尿素复合肥中,较低的氮盐有利于β-胡萝卜素的积累;1.0mmol/L尿素培养的D. salina OUN 07叶绿素a含量最高(48.5mg/g),较高的氮盐有利于叶绿素a的合成;D. salina OUN 07脂肪酸主要由16:0、18:1和18:2ω-6组成,其中0.75mmol/L尿素组脂肪酸含量最高;氮源对D. salina OUN 07蛋白含量也有显著影响,NH4NO3/尿素组蛋白含量(33.61%)最高;建立了三种氮源吸收的动力学方程.     

Analysis of Interannual Variations of Inorganic Nitrogen in the Bohai Sea

According to the Bohai Sea cross-section data during 1985～1998, the high concentration inorganic nitrogen in the Bohai Sea section bottom layer water nearshore diffused and transferred to the middle of the Bohai Sea year after year. The interannual variations of the concentration of inorganic nitrogen in the Bohai Sea section bottom layer water may reflect the degree of eutrophication more steadily. The nitrate nitrogen and nitrite nitrogen are used to show quasi-equilibrium state interannual variations, but with the aggravation of seawater pollution, the quasi-equilibrium state of interannual variations has been broken and the marine biological-chemical processes can only maintain the secondary part of the interannual variations in a quasi-equilibrium state, but are not sufficient to prevent the main pan of interannual variations from deviating from the quasi-equilibrium state. The spatial distributions of inorganic nitrogen would be affected by the reproduction and swarming of marine life.     

Biogeochemical Character of Dissolved Inorganic Nitrogen and Phosphate at Plume Front in the Changjiang River

Biogeochemical character of dissolved inorganic nitrogen and phosphate at plume front is studied based on the data, which were observed in the Changjiang River Estuary in 1988. The results are as follows: The concentrations of nitrate and phosphate change abruptly at plume front and halocline. The concentrations of NO-2 and NH 4 are very high at 10～25m depth. The vertical circumfluence transports NO-3 and PO3-4 , which are released from organisms at the bottom to phytoplankton.