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Dwarf shrub litter is thought to be of poor quality and palatability for macro-decomposers. In laboratory feeding experiments, however, it was found that this litter type represents a potential food source for earthworms and millipedes. Here we tested whether this is true under natural conditions by conducting a 1 year field experiment on an abandoned alpine pasture in Tyrol (Austria). As the natural isotopic signatures of plant litter do not allow discriminating between different plant species, dwarf shrub litter, artificially enriched in 15N, was offered in experimental plots to the macro-decomposer community. Both the earthworm Lumbricus rubellus and the millipede Cylindrojulus fulviceps fed on dwarf shrub litter as indicated by their increased δ15N signatures, but IsoError analysis indicated a clear preference for grass litter for all macro-decomposer species investigated.Soil δ15N signatures were only marginally affected by the experimental provision of 15N-enriched dwarf shrub litter, whereas litter from other, unlabelled, plants became enriched by the isotopic tracer to some extent. Except for one grass species, plants harvested at the end of the experiment were not enriched in 15N, suggesting that the N-uptake from decomposing litter material by plants on abandoned alpine pastureland is slow. 相似文献
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Different explanations have been proposed for why terrestrial isopods prefer, and gain from, feeding on microbially inoculated food materials. In the present study, no-choice feeding experiments are used to test three contrasting, but not mutually exclusive, hypotheses. (1) The digestion and nutritional utilization of microbial cells enhance the nutritive value of leaf litter; (2) extracellular digestive enzymes of microbial origin promote digestion of leaf litter; (3) leaf litter-colonizing microbiota serve as indicators for easily digestible leaf litter of high nutritive value. Predictions derived from these hypotheses are compared with the results of a study with experimentally manipulated leaf litter, serving as food sources for the common woodlouse Porcellio scaber. Leaf litter-colonizing microbiota increased consumption of leaf litter by isopods and contributed somewhat to biomass gain of isopods, but not to the assimilation of ingested food. Thus, the present results coincide with predictions derived from hypothesis (3) suggesting that leaf litter-colonizing microbiota stimulate consumption by indicating high food quality. Their positive effects on assimilation and growth, however, are context-specific, being stronger in case of high-quality food than in case of low-quality food. 相似文献
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Haraguchi K Kato Y Ohta C Koga N Endo T 《Journal of agricultural and food chemistry》2011,59(24):13102-13109
Marine sponges collected in Palau, Micronesia, were investigated for hydroxylated or methoxylated analogues of brominated diphenyl ethers (BDEs), brominated dibenzo-p-dioxin (BDD), and brominated biphenyls. The neutral fractions of Haliclona sp. and Callyspongia sp. contained 2'-methoxy-2,3',4,5'-tetraBDE, 6-methoxy-2,2',4,4'-tetraBDE, 2',6-dimethoxy-2,3',4,5-tetraBDE 2,2'-dimethoxy-3,3',5,5'-tetrabromobiphenyl, several methoxy-triBDEs, and dimethoxy-penta-/hexaBDEs. The methoxylated BDEs in sponges were strikingly similar to those of local fish living in the western Pacific Ocean. The total concentrations of these compounds (ΣMeO-PBDE) in both sponges were 63.5 μg/g extractable organic matter (EOM) for Haliclona sp. and 36.5 μg/g EOM for Callyspongia sp., which were about 2 orders of magnitude higher than the levels seen in tropical coral reef fish (unicornfish or surgeonfish) (280-290 ng/g lipid) and groupers (550 ng/g lipid) from Okinawan coastal waters. The phenolic fractions of both sponges contained hydroxy-methoxy tetra-/pentaBDEs as well as hydroxy-tetraBDD, in addition to the corresponding phenolic tetraBDE analogues. Although the total concentrations of phenolic products (27-80 μg/g EOM) in both sponges fell within a range comparable to the methoxylated products, ΣOH-PBDE in local fish were trace level (less than 10 ng/g lipid of) or undetectable. This survey indicates that marine sponges are a possible source of the MeO-PBDE analogues that biomagnify via the food chain to the higher trophic organisms in the western Pacific, whereas the distribution of the corresponding hydroxylated analogues is limited. 相似文献
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Sánchez A Ysunza F Beltrán-García MJ Esqueda M 《Journal of agricultural and food chemistry》2002,50(9):2537-2542
The bioconversion of vineyard pruning and grape pomace by Pleurotus spp. using a solid state fermentation (SSF) was evaluated. Fruiting body production and chemical changes in the substrates after harvesting were measured. Biological efficiency and bioconversion ranged from 37.2 to 78.7% and from 16.7 to 38.8%, respectively. The best substrates for mycelial growth and mushroom yield were the mixtures with higher vineyard pruning content. Inclusion of pruning content had higher phenolic components and total sugars, better C/N ratio, and lower crude fat and total nitrogen than pomace. On the contrary, mycelium grew more slowly and scarcely in all treatments with 100% grape pomace. Moisture, protein, fat, and lignin contents were generally higher in mixtures with higher pomace proportion, whereas neutral detergent fiber, hemicellulose, and cellulose contents were higher with pruning content. Pleurotus strains may act depending on the availability of fiber fractions of substrate, and dynamic changes in digestion might occur as these fractions change during fungal growth. The recycling of viticulture residues through SSF by Pleurotus has great potential to produce human food and yields an available high-fiber feed for limited use in ruminants. 相似文献
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基于“源”、“汇”过程的农业非点源污染模型构建及应用 总被引：2，自引：1，他引：1
根据农业非点源污染产移特点, 将农业非点源污染模型分为田间产污的“源”模块以及模拟污染物在排水沟渠中运移的“汇”模块, 其中“源”模块又包括农田灌溉(降水)排水子模块及农田灌溉(降水)排水中污染物浓度计算子模块。应用DRAINMOD模型模拟田间尺度的灌溉(降水)排水, 同时将农田的施肥和灌溉过程“合成”作为田间污染物浓度的脉冲输入, 以逆高斯分布作为综合作用函数, 建立农田尺度的灌溉排水污染物浓度估算模型, 二者结合构成农业非点源污染田间产污模块; 应用一维水动力学基本方程和非保守性污染物迁移方程, 建立农业非点源污染物沟渠“汇”模块。并以黄河上游青铜峡灌区为例进行了示例应用, 依据典型田块以及排水沟渠农业非点源污染监测试验资料, 结合灌区作物种植结构, 计算了2008年5~9月青铜峡灌区输出污染负荷, 结果为盐分470 099 t、总磷98.17 t、总氮3 593 t、硝态氮2 122 t、氨态氮426 t。通过示例验证, 表明所建模型具有较好的模拟效果, 可进一步推广应用。 相似文献
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Boutelle KN Fulkerson JA Neumark-Sztainer D Story M French SA 《Public health nutrition》2007,10(1):16-23
OBJECTIVE: The purpose of the present study was to examine the prevalence of fast-food purchases for family meals and the associations with sociodemographic variables, dietary intake, home food environment, and weight status in adolescents and their parents. DESIGN: This study is a cross-sectional evaluation of parent interviews and adolescent surveys from Project EAT (Eating Among Teens). SUBJECTS: Subjects included 902 middle-school and high-school adolescents (53% female, 47% male) and their parents (89% female, 11% male). The adolescent population was ethnically diverse: 29% white, 24% black, 21% Asian American, 14% Hispanic and 12% other. RESULTS: Results showed that parents who reported purchasing fast food for family meals at least 3 times per week were significantly more likely than parents who reported purchasing fewer fast-food family meals to report the availability of soda pop and chips in the home. Adolescents in homes with fewer than 3 fast-food family meals per week were significantly more likely than adolescents in homes with more fast-food family meals to report having vegetables and milk served with meals at home. Fast-food purchases for family meals were positively associated with the intake of fast foods and salty snack foods for both parents and adolescents; and weight status among parents. Fast-food purchases for family meals were negatively associated with parental vegetable intake. CONCLUSIONS: Fast-food purchases may be helpful for busy families, but families need to be educated on the effects of fast food for family meals and how to choose healthier, convenient family meals. 相似文献
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Jiménez-Martín E Ruiz J Pérez-Palacios T Silva A Antequera T 《Journal of agricultural and food chemistry》2012,60(10):2456-2463
The suitability of a one-step derivatization procedure using N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide for the simultaneous assay of 22 free amino acids and its application for their analysis in six animal source foods (pork, dry cured ham, chicken stock, fresh cheese, ripened cheese, and dry salted sardine) by GC-MS were studied. All 22 free amino acid derivatives were correctly detected and resolved. Reproducibility (%RSD) of the method was in the range of 1.9-12.2%. Detection and quantitation limits of the analytical procedure ranged from 0.01 to 0.46 mg/100 g dry weight and from 0.02 to 1.55 mg/100 g dry weight, respectively. The calibration curves were linear within the range 0.1-15.0 mg/100 g with correlation coefficient values (R(2)) from 0.9891 to 0.9983. All analyzed food products showed free amino acid contents similar to those found in the scientific literature. The proposed GC-MS method for the determination of free amino acids in animal source food can be used in routine for both analytical and research purposes. 相似文献
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晋江流域非点源氮磷负荷及污染源解析 总被引：8，自引：0，他引：8
计算流域非点源氮磷负荷并以此开展源解析对于水体污染控制具有重要意义。基于DEM数据,运用GIS工具划分子流域,提取土地利用和土壤类型等空间相关资料,通过调查及小区试验获取模型参数,建立晋江流域非点源氮磷污染负荷模型;利用SLURP模型和输出系数模型分别核算流域内不同景观类型土地输出径流和农村污染溶解态氮磷负荷,利用修正的USLE土壤侵蚀通用方程核算吸附态氮磷负荷,并进行污染源解析。结果表明:晋江流域非点源氮负荷为12298.95t/a,大部分为溶解态氮,占到了94.13%,主要来自畜禽养殖、农田径流和农村生活污水,其源贡献率分别为31.72%、26.38%和17.44%;非点源磷负荷为667.04t/a,溶解态磷和吸附态磷对流域总磷负荷贡献比例相当,分别为56.73%和43.27%,主要来自土壤侵蚀、农田径流和农村生活污水,其贡献率分别为43.27%、21.10%和12.25%。总体分析表明,土壤侵蚀、农田径流和畜禽养殖是影响晋江流域非点源氮磷负荷的主要污染源,亟待优先控制。 相似文献
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化肥与粮食安全 总被引：47，自引：8，他引：47
本文根据相关文献资料,综述了化肥在保障我国粮食安全中的作用与贡献,分析和预测了实现2010、2015、2020年粮食总产目标所需新增化肥的数量。根据近6年来我国粮食生产中出现的问题,指出要保障我国粮食安全,除了继续发展化肥工业,增加化肥用量之外,国家应采取其他相应措施,包括稳定粮食作物的种植面积(至少应维持在11000万公顷水平);调整粮食价格,保护农民种粮积极性;改善农田基本生产条件,推行节水灌溉技术,促进粮食均衡增产;适度提高粮食净进口份额等等。单纯依靠增加化肥的投入,实现国内粮食供需平衡,不仅代价太大(包括资源、环境和成本代价),市场和农民也不一定能够接受。 相似文献
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中国水资源和粮食安全问题探讨 总被引：22，自引：7，他引：15
中国是世界人口最多的发展中国家,用占全球7%的土地、8%的淡水养活占全球22%的人口.但随着人口的持续增长,气候干旱和生态境破坏以及污染的不断扩大和加重,水和耕地资源的不断减少,中国在水资源和粮食安全方面将面临巨大的压力与挑战.中国干旱半干旱的西北地区,有70%左右的贫困人口,粮食安全问题长期存在,经济发展缓慢.目前中国政府实施的西部大开发战略,减免农业税费,增加经济投入和水利工程等建设项目,是解决西北地区贫困的关键. 相似文献
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Food in its many manifestations allows us to explore the global control of health and to examine the ways in which food choice is moulded by many interests. The global food market is controlled by a small number of companies who operate a system that delivers 'cheap' food to the countries of the developed world. This 'cheap' food comes at a price, which externalises costs to the nation state in terms of health consequences (diabetes, coronary heart disease and other food-related diseases) and to the environment in terms of pollution and the associated clean-up strategies. Food policy has not to any great extent dealt with these issues, opting instead for an approach based on nutrition, food choice and biomedical health. Ignoring wider elements of the food system including issues of ecology and sustainability constrains a broader understanding within public health nutrition. Here we argue that public health nutrition, through the medium of health promotion, needs to address these wider issues of who controls the food supply, and thus the influences on the food chain and the food choices of the individual and communities. Such an upstream approach to food policy (one that has been learned from work on tobacco) is necessary if we are seriously to influence food choice. 相似文献
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We offer a critique of Canada's approach to domestic food security with respect to international agreements, justiciability and case law, the breakdown of the public safety net, the institutionalisation of charitable approaches to food insecurity, and the need for 'joined-up' food and nutrition policies. We examined Canada's commitments to the right to food, as well as Canadian policies, case law and social trends, in order to assess Canada's performance with respect to the human right to food. We found that while Canada has been a leader in signing international human rights agreements, including those relating to the right to food, domestic action has lagged and food insecurity increased. We provide recommendations for policy changes that could deal with complex issues of state accountability, social safety nets and vulnerable populations, and joined-up policy frameworks that could help realise the right to adequate food in Canada and other developed nations. 相似文献
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Psycho- and vasoactive compounds in food substances 总被引：1，自引：0，他引：1
W Lovenberg 《Journal of agricultural and food chemistry》1974,22(1):23-26