Impact of harvesting and logging slash on nitrogen and carbon dynamics in soils from upland spruce forests in northeastern Ontario

The potential impact of timber harvesting in the boreal forest on aquatic ecosystem water quality and productivity depends in part on the production of nutrients within the soil of the harvested catchment. Nitrogen supplied by organic matter decomposition is of particular interest because of the important role that N plays in biotic processes in surface waters, and in forest nutrition in general. Logging slash quality and input to the forest floor has the potential to influence N availability after harvest on clearcut sites. Net production of organic and inorganic-N and microbial biomass C and N concentrations were determined during a 90-day laboratory incubation at constant temperature and moisture. Incubated soils included F horizon and shallow mineral soil horizons (0-5 cm) from unharvested and full-tree harvested (2 and 12 growing seasons since harvest) boreal forest sites at the Esker Lakes Research Area (ELRA), in northeastern Ontario, Canada. In an ancillary experiment, black spruce foliage was added to unharvested forest floor material after 30 days during a 90-day laboratory incubation to simulate the influence of logging slash from full-tree harvesting on C and N dynamics. Twelve-year old clearcut F horizon material released on average 75 and 5 times more -N and 3 and 2 times as much inorganic-N than soil collected from unharvested and 2-year-old clearcuts, respectively. This increase in -N accumulation during the incubation was accompanied by decreases in both exchangeable -N and microbial biomass C and N levels. Net daily changes in microbial biomass N were significantly related to organic and inorganic-N accumulation or loss within the F horizon. Mineral soil release of inorganic-N was lower than release from the forest floor. Nitrate-nitrogen accumulation was lower, and -N accumulation was higher in mineral soil from unharvested sites when compared to 12-year-old clearcuts. Calculated harvest response ratios indicated that incubated mineral soil from the 12-year-old clearcut sites released significantly greater amounts of -N than 2-year-old clearcuts. Incorporation of black spruce needles into F horizon material reduced the production of organic and inorganic-N and increased microbial biomass N. Laboratory incubations of F horizon and shallow mineral soil from 12-year-old clearcuts suggested that these boreal soils have the capacity for increased inorganic-N production compared to uncut stands several years after harvesting. This has the potential to increase N availability to growing boreal forest plantations and increase N leaching due to greater -N levels in the forest soil.     

Uptake and translocation of non-ionised pesticides in the emergent aquatic plant parrot feather Myriophyllum aquaticum

The uptake of four (14)C-labelled non-ionised compounds, the methyl carbamoyloxime insecticide/nematicide oxamyl and three model phenylureas, from solution by rooted stems of the aquatic plant parrot feather [Myriophyllum aquaticum (Vell.) Verdc], together with translocation to the emergent shoots, was measured over periods of 24 and 48 h. Uptake into the submerged tissues of roots and stem base could be ascribed to two processes: movement into the aqueous phase of cells and then partitioning onto the plant solids. This latter process was related to lipophilicity (as measured by the l-octanol/water partition coefficient, K(ow)) and gave rise to high uptake rates of the most lipophilic compounds. Translocation to shoots was passive and was optimal at log K(ow) approximately 1.8, at which the efficiency of translocation of compound was about 40% of that of water. This optimum log K(ow) was identical to that observed previously in barley, although the translocation efficiency was somewhat less in parrot feather. Solvation parameters were applied to model uptake and translocation of a set of ten compounds by barley with the particular objective of understanding why translocation efficiency is lower at log K(ow) > 1.8.     

城市静态小水体生态修复措施与生态服务价值评估研究

城市静态小水体污染是城市环境污染的重要问题之一。针对城市静态小水体的特点,依据稳态转换理论和生物操纵理论,形成适应于城市静态小水体的生态修复措施,并运用于武汉市青山区倒口湖水生态修复工程。工程实施后湖水水质得到明显改善,其中,水体透明度由0.2~0.4m提高至1.0~1.5m,溶解氧浓度由1.82~2.35mg/L上升至5.21~6.28mg/L,CODMn浓度由14.96~16.3mg/L降低至3.56~5.01mg/L,TN浓度由2.61~2.99mg/L降至1.27~1.6mg/L,TP浓度由0.43~0.62mg/L降至0.06~0.12mg/L。进一步对倒口湖水生态系统的供给、调节、文化以及支持4方面的服务价值进行评估,通过对水生态系统服务价值评价指标计算得出,工程实施前后水生态系统服务价值分别为299.34万元和645.62万元,新增服务价值346.28万元。在增量价值中固碳释氧、净化水质指标占比最大,表明在水生系统动植物的协同作用下,倒口湖的水质条件得到明显改善。     

Strategies for further development of aquatic feeds

ABSTRACT: To date, aquatic feeds have depended heavily on fishmeal and fish oil as their source of protein and lipid. However, the feed industry is encountering shortfalls in the availability of these ingredients because of a decline in the number of fish captured in the wild and the increased human demand for some of the species currently being used for fishmeal and oil production. Therefore, efforts are now being directed in different parts of the world to finding alternative quality ingredients, which ideally are less expensive and readily available for use in practical diets. The data accrued have shown that a large proportion of both fishmeal and fish oil can be replaced by other protein and lipid sources. However, it is emphasized that an optimal essential amino acid balance be maintained and that the n-3 highly unsaturated fatty acid requirement be satisfied when combining economical protein and lipid ingredients. Newly developed feeds should aim at being nutrient-dense in order to reduce the output of solid, P and N waste. This can be done through improving nutrient availability, optimizing the digestible protein to energy balance of the diet, and replacing dietary fishmeal with alternate ingredients. These diets should also be effective for maintaining good health and improving disease resistance in fish through enhancement of immune responses. A wholesome approach to culturing fish would be to use appropriate feeding standards that are aimed not only at improving economic returns but also at developing a lasting cohabitation of sustainable aquaculture and a cleaner environment. Furthermore, in the 2lst century aquaculture would still retain its place as a prominent source of food protein, signifying that fish feed research remains a forceful area in discovering better feeds for the industry.     

水产胶原蛋白及胶原多肽的研究进展

胶原蛋白是动物结缔组织中的主要成分,是动物体内含量最多、分布最广、具有免疫学性质[1]的蛋白质,在皮革业、影像业、制药业、糖果生产、生物医学原料和食品工业中有广泛的应用。最近,国外研究表明,胶原水解所得的胶原多肽不仅具有很好的消化特性,而且还具有许多生理活性功能,     

舟山水产加工业的现状分析及发展对策探讨

近来,舟山水产加工业的发展较之前有所滑坡,本文通过对近年来舟山水产加工业的总体现状进行分析,并深入探讨问题的根源,进而对舟山水产加工业今后的发展对策提出了若干建议。     

入世以来中国水产品贸易的格局特征及发展前景

水产品是中国传统的出口优势产品。加入WTO以来,中国水产品贸易在进出口双向快速增长的局面下,保持了净出口态势。文章在总结中国水产品入世几年来进出口的发展趋势、产品结构以及国别特征的基础上,着重分析了其发展前景。结果表明,增强质量竞争力是优势水产品出口实现持续增长的关键,未来几年对国外捕捞类水产品进口将继续大规模增长,中国水产品进出口的产品结构特征短期内不会有显著变化。最后,基于提高出口水产品竞争力、优化中国水产品贸易格局的目的提出了一些对策建议。     

海产品中溴酚类海洋风味素的气相色谱—质谱联用分析

建立了海产品中的溴酚类海洋风味素的毛细管气相色谱-质谱联用检测法。样品中溴酚类化合物在挥发油测定器中用乙酸乙酯通过循环蒸馏萃取,浓缩后用电子轰击源在特征离子碎片扫描检测模式下进行检测。结果表明,5种溴酚类化合物在SBP-50柱上得到良好的分离,色谱出峰尖锐,没有杂峰干扰。本方法在2.5～40 mg·L~(-1)浓度范围内线性关系良好,最低检测限低于1ng·mL~(-1)。当向25.00g样品中添加溴苯酚各2.0μg时,平均回收率分别达到90.45％(2-BP)、60.49％(4-BP)、85.79％(2,4-DBP)、84.98％(2,6-DBP)、90.80％(2,4,6-TBP),标准相对偏差为1.37％～4.16％。对市场上销售的几种海洋经济动物测定,溴酚类风味素含量在5.40～31.38 ng·g~(-1)范围内,而所测得的淡水青虾中溴酚类风味素含量只有0.18 ng·g~(-1)。     

张掖黑河湿地附植硅藻群落初步研究 ——以张掖国家湿地公园为例

研究张掖国家湿地公园附植硅藻群落现状,为保护寒、旱区湿地水生植物与生物多样性提供理论依据。2017年夏、秋从张掖国家湿地公园浅水湖泊采集12种常见水生植物,采集植物上附植硅藻,并在水质富营养化评价的基础上进一步分析硅藻的种类分布、优势种、多样性和聚类性。结果表明,张掖国家湿地公园水体轻度富营养化;共检出附植硅藻39属158种(含变种),其中舟形藻属种类最多(18种),其次为菱形藻属(16种)、桥弯藻属(15种)和脆杆藻属(13种);Achnanthedium minutissimum为分布最为广泛的优势种,其次为Ulnaria acus和Encyonopsis subcryptocephala;Shannon-Weaver多样性指数在1.41～3.13,Pielou均匀度指数在0.58～1.07,均是秋季显著高于夏季(P0.05,t-test);Cody指数与聚类分析表明,在同一时期内附植硅藻种类组成的相似程度和优势种分布对部分宿主植物的选择趋于一致,但也有部分宿主植物之间附植硅藻群落结构仍然存在较大差异。