Determination of nutrients and volatile constituents of Agaricus bisporus (brown) at different stages

BACKGROUND: The physical properties, proximate composition, mineral and vitamin contents, and estimated volatile components of Portobello mushroom, Agaricus bisporus (brown), were analyzed in three flushes and at two different harvest times. The results showed different trends in the flushes and harvest terms studied. RESULTS: The mean values of texture, diameter, and protein of the harvested produce were 1.78–1.97 kg mm^?2, 4.67–5.02 cm, and 4.18–3.31% wet weight basis (wb), respectively. The mean Zn, Fe, P, Mg, K, Na, and Ca contents of both harvests (mg kg^?1 wb) were 8.15–7.07, 7.40–7.96, 1180.93–1038.69, 88.05–76.29, 213.29–238.82, 2652.0–2500.89, and 534.2–554.80, respectively. In terms of vitamin C, folic acid, thiamin, riboflavin, and niacin, the mean contents (mg kg^?1 wb) were 6.75–3.97, 0.09–0.08, 0.085–0.09, 0.27–0.29, and 3.62–2.94, respectively. The estimated volatile components comprised 18‐ or 16‐carbon compounds such as octadecanoic acid, hexadecanoic acid derivatives, and other important volatiles like dl‐limonene, n‐nonane, benzendicarboxylic acid, and cis‐linoleic acid esters. CONCLUSION: Nutritive contents and estimated volatiles of Portobello mushroom were evaluated in detail at different stages. Copyright © 2009 Society of Chemical Industry     

Orthophosphate concentrations in the River Thames: reductions in the past decade

Ten years ago plans were made to reduce the phosphorus load from sewage-treatment works' effluents into the River Thames. This was driven by the EC Urban Wastewater Treatment Directive in relation to sensitive areas (eutrophic). Modelling work identified the most significant loads to tackle first. Phosphorus removal had been commissioned at 36 works by 2003. The orthophosphate load to the River Thames from these works has reduced from 5755 to 688 kg P/day. The impact of the improvement programme on the quality of the river was assessed by comparing pre- and post-investment data. Orthophosphate concentrations in the river have reduced from between about 0.5 and 2 mg P/L to 0.2 and 0.4 mg P/L. These observations match the model predictions. Chlorophyll a concentrations in the river have also reduced. This was unexpected given that the orthophosphate concentrations still exceed the values thought to be limiting for algal growth.     

多点肥料效应函数方程分类与土壤养分相关性研究

采用主成分分析方法对多点动态肥料试验聚类分析结果与土壤养分间的关系进行了研究。结果表明,土壤氮素状况是分类的第一主因子,磷素状况是第二主因子,有机质含量是第三主因子。确定类肥料效应函数应用范围的主要依据是土壤碱解氮和全氮含量,其次是土壤有效磷含量,再次是土壤有机质含量。     

河南开封土壤养分变化特征及其持续利用途径研究

通过 1 984～ 1 998年河南开封不同土壤耕层有机质与氮磷钾养分分析 ,论述了不同农业利用方式和农田管理措施下不同土壤耕层养分的时空变化特征和硝态氮累积特性 .由于“重氮磷 ,轻有机肥 ,忽视钾素补给” ,土壤养分变化的总趋势以下降 ,钾素耗竭性明显 .土壤养分空间变化较为复杂 ,但不同土壤间耕层养分为普通淡色潮湿雏形土 >底锈干润雏形土 >石灰淡色潮湿雏形土 >灌淤旱耕人为土 >简育干润雏形土 >干润砂质新成土 .硝态氮累积表现为由上至下递减或由上至下递增和相对积累于土体某一深度 .最后研究提出了土壤持续利用的有效技术途径 .     

云南昌宁蔗区不同耕层土壤养分的垂直分布

研究了蔗园土壤养分的垂直分布特征。结果表明:(1)不管是在旱地蔗园还是在水田蔗园,0～30cm土层的有机质、水解氮、速效磷、速效钾等主要养分含量明显高于30～60cm的土层,但全氮、全磷、全钾在0～30cm土层与30～60cm土层之间没有明显的变化。(2)旱地蔗园的有效铁、有效锰和有效铜0～30cm土层比30～60cm土层高,有效锌含量在0～30cm的土层与30～60cm的土层之间变化不大。     

Factors structuring macroinvertebrate communities in a headwater stream and its springs in the Upper Austrian Limestone Alps

The Almbach, a headwater stream in the Upper Austrian foothills of the Alps bordered by mountain pastures was studied to gain insight into the benthic macroinvertebrate community and its habitat. Two springs, one of them fenced in to prevent livestock access, and two more sites of the headwater section were investigated. A discriminant analysis (DA) based on hydrochemistry and phytobenthos revealed three functions with 86% of all samples correctly classified to the four sites. The first function clearly separated the two springs with phosphorus and oxygen as the most important discriminating factors. Spring sites and headwater sites were split up by the second function mainly due to nitrate concentration, but no differences could be detected for the two stream sites. With the exception of the fenced spring, indicator taxa could be assigned to all sites by means of an Indicator Species Analysis (ISA). Polyvalent taxa groups such as Gastropoda and Ostracoda were indicators for the unfenced spring site. This is in accordance to observed low abundances of sensitive plecopteran taxa and suggests a negative impact of livestock trampling on the invertebrate community. Redundancy Analysis explained 99% of the macroinvertebrate‐environment relation. The first axis separated springs from stream sites and was correlated with nitrate, pH, water temperature and phytobenthos eveness. Phosphorus was responsible for splitting the unfenced spring and the downstream station from the fenced spring and the upstream location along the second axis. Ephemeropteran taxa like Habrophlebia sp. were related to elevated pH, increased water temperature and low nitrate concentrations. In accordance to the ISA, nitrate played an important role for tolerant Gastropoda and Ostracoda at the unfenced spring. Copyright © 2010 John Wiley & Sons, Ltd.     

Seasonal water level fluctuations: Implications for reservoir limnology and management

With the purpose of finding out whether seasonal water level fluctuations could affect water quality in a reservoir subjected to those changes, trends in environmental variables and in phytoplankton and zooplankton assemblages were analysed. The reservoir's hydrological cycle was characterized by three regimes. The maximum level phase lasted from January to the beginning of June, the emptying phase existed between mid‐June to the beginning of September and the minimum level phase lasted from mid‐September to the beginning of the first autumn/winter rain events. The highest values of total phosphorus, soluble reactive phosphorus, nitrate, water colour and chlorophyll a were found during the minimum level phase. The phytoplankton assemblage was dominated by taxa typical of meso‐eutrophic environments during the emptying and minimum level phases. However, during the maximum level phase, taxa generally found in more oligotrophic systems were observed here also. Similar to other disturbed systems, the zooplankton assemblage was dominated by Rotifera, except in summer and autumn when the cladoceran Ceriodaphnia quadrangula and/or the copepod Tropocyclops prasinus became dominant. Although those shifts seem to be related to water level variations, further research is needed to evaluate to what extent they might also be induced by other seasonal factors acting independently of water fluctuations. Based upon the obtained data, suggestions for reservoir management are proposed.     

Inexpensive in situ time-integrating seawater nutrient sampler

An in situ time-integrating seawater sampler in which air escaping from the sample bottle through a capillary regulates flow of seawater into the sampler is described for determination of average plant nutrient concentration during a 10–50 h period. The sampler collected water at a constant rate which was approximately equal to that predicted from the Hagen-Poiseuille equation. The sampler has advantages over those described previously: it is less susceptible to blockage from suspended particulates in seawater, less expensive, and the seawater collection rate should be less temperature-dependent.     

Evaluation of the nutritional quality of four unexplored aquatic weeds from northeast India for the formulation of cost-effective fish feeds

A study was conducted to evaluate the nutritional potential of four commonly available, unexplored aquatic weeds namely, Salvinia cuculata, Trapa natans, Lemna minor and Ipomoea reptans from northeast India for ascertaining their suitability for utilization as supplementary fish feed with the aim to reduce the cost of commercial feeds. Results of proximate analysis showed that the crude protein content of the aquatic weeds ranged between 11.0% and 32.2% (w/w), whereas crude fibre and ash contents varied between 4.2% and 20% (w/w), and 13.3% and 31.2% (w/w), respectively. Protein to energy ratio (P/E) of these weeds ranged between 30.7 mg/kcal and 95.3 mg/kcal and the highest value was displayed by I. reptans. All these aquatic weeds contained high amounts of vitamins E and C and mineral elements required for the normal growth and development of fish.