Rapid amino acid cycling in arctic and antarctic soils

Amino acids constitute one of the largest inputs of organic nitrogen (N) to most polar soils and have been hypothesized to be important in regulating vegetational succession and productivity in Arctic ecosystems. Our understanding of amino acid cycling in these soils, however, is poor. The aim of this study was to investigate the size and rate of turnover of the amino acid pool in a range of Arctic and Antarctic soils. Our results indicate that in polar soils with either high or low ornithogenic inputs the amino acid pool is small in comparison to the inorganic N pool (NO^–₃ and NH⁺₄). The free amino acid pool constituted only a small proportion of the total dissolved organic nitrogen (DON) pool in these soils. Here we show that these low concentrations may be due to rapid use by the soil microbial community in both Arctic and Antarctic soils. The turnover of the amino acid pool in soil was extremely rapid, with a half-life ranging from 2 to 24 h, indicating that this N pool can be turned over many hundred times each summer when polar soils are frequently unfrozen. The implications of amino acids in N cycling and plant and microbial nutrition are discussed.     

Impact of Land Use on Soluble Organic Nitrogen in Soil

Although it has been hypothesized that soluble organic nitrogen (SON) plays a central role in regulating productivity in some terrestrial ecosystems, the factors controlling the size of the SON pool in soil remain poorly understood. Therefore our principal aim in this work was to assess the impact of seven different land use systems (rough and managed grassland, deciduous and coniferous woodland, heathland, wetland and tilled land) on the size of the SON and inorganic N (NO ₃ ^– , NH ₄ ⁺ ) pools in the surface soil layer (0–15 cm). After extraction with deionised water, we found that in most cases the size of the water extractable organic N (WEON) pool was similar in size to the inorganic N pool. In contrast, the KCl extractable organic N (KClEON) pool constituted the dominant form of soluble N in soils under all land uses, perhaps indicating that significant amounts were held on the soil exchange phase. In contrast to inorganic N, which varied significantly with land use, the size of the KClEON and WEON pool was similar for all land uses with the exception of KClEON in tilled land, where significantly lower amounts were observed. We conclude that SON constitutes an important soil N pool in a broad range of land uses, and that its role in microbial N assimilation, plant nutrition and ecosystem responses to atmospheric N deposition warrants further attention. SAFRD, University of Newcastle, Newcastle-upon-Tyne, NE1 7RU, U.K.     

改进型石灰混凝法去除城市污水二级出水中有机物的研究

将石灰混凝处理后的沉淀泥渣进行回流，对石灰混凝法进行改进，研究改进后的石灰混凝法对城市污水二级出水中有机物的去除效果。结果表明，活性泥渣回流有利于提高石灰混凝法对城市污水二级出水中有机物的去除。回流位置在石灰投加前、复合絮凝剂投加后，最佳回流量为新泥渣产生量的100％～200％，活性泥渣回流的最佳pH为11．0～11．5；活性泥渣中CaCO3、Mg(OH)2、Fe(OH)3等沉淀物以及有机高分子絮体均有助于提高其对有机物的去除效果，其中Mg(OH)2沉淀物起主导作用；含循环泥渣的活性污泥回流，对有机物的去除效果无明显影响。     

The Ethical Contract as a Tool in Organic Animal Husbandry

This article explores what an ethicfor organic animal husbandry might look like,departing from the assumption that organicfarming is substantially based in ecocentricethics. We argue that farm animals arenecessary functional partners in sustainableagroecosystems. This opens up additional waysto argue for their moral standing. We suggestan ethical contract to be used as acomplementary to the ecocentric framework. Weexpound the content of the contract and end bysuggesting how to apply this contract inpractice. The contract enjoins us to share thewealth created in the agroecosystem (by ourjoint contributions) by enjoining us to carefor the welfare and needs of the individualanimal, and to protect them from exploitation(just as human co-workers should not beexploited). The contract makes promoting goodanimal welfare a necessary condition forbenefiting farm animals. Animals for their partare guaranteed coverage under the contract solong as they continue to contribute to thesystem with products and services.     

NITROGEN AND ORGANIC MATTER LOSSES IN NO‐TILL CORN CROPPING SYSTEMS1

ABSTRACT: Intensive cropping systems based on mechanical movement of soil have induced land degradation in most agricultural areas due to soil erosion and soil fertility losses. Thus, farmers have been increasing fertilization rates to maintain an economically competitive crop yield. This practice has resulted in water quality degradation and lake eutrophication in many agricultural watersheds. Research was conducted in the Patzcuaro watershed in central Mexico to develop appropriate technology that prevents nonpoint source pollution from fertilizers. Organic matter (OM) and nitrogen (N) losses in runoff and nitrate (NO₃‐N) percolation in Andisols with corn under conventional till (CT) and no‐till (NT) treatments using variable percentages of crop residue as soil cover were investigated for steep‐slope agriculture. USLE type runoff plots were used to collect water runoff, while suction tubes with porous caps at 30, 60, and 90 cm depth were used to sample soil water solutes for NO₃‐N analyses. Results indicated a significant reduction of N and OM losses in runoff as residue cover increased in the NT treatments. Inorganic N in runoff was 25 kg/ha for NT without residue cover (NT‐0) and 6 kg/ha for the NT with 100 percent residue cover (NT‐100). Organic matter losses in runoff were 157 and 24 kg/ha for the NT‐0 and NT‐100 treatments, respectively. Nitrate‐N percolation was evident in CT and NT with 100 percent residue cover (NT‐100). However, NT‐100 had higher NO₃‐N concentration at the root zone, suggesting the possibility of reducing fertilization rates with the use of NT treatments.     

气浮+生物接触氧化工艺处理食品加工废水

通过气浮 生物接触氧化工艺处理速冻食品加工废水的实验、设计和工程运行,结果表明:废水COD去除率能达到97%以上,使得最终出水的COD＜100mg/l.该工艺对冲击负荷有较强的适应性.     

茶粕有机肥的开发与利用

论述了生物有机肥在发展农业生产中的重要地位,以及生产中存在着的大量使用集约化畜禽养殖场的畜禽粪对土壤、水体等环境质量和农产品质量安全产生严重影响的问题,提出以茶粕作为原料生产有机肥具有生产过程相对安全、克服有机肥二次污染的优点.此外,茶叶次生代谢物茶多酚、茶色素、茶皂素和茶皂甙等具有抗氧化、清除自由基、络合金属离子、调节植物生长和生物防虫、灭虫等独特生理功效,将极大地提高茶粕有机肥的生物有效性,显示出其广阔的应用前景.     

新疆发展有机食品生产与可持续发展

从地域优势、农产品特征、生态条件等方面,论述了新疆发展有机食品生产的适宜性和重要意义.认为新疆发展有机食品生产可以利用得天独厚的气候、水土等自然资源,以及工业污染环境影响较小的有利条件,保护和改善农村生态环境,充分发挥独特的农产品资源优势,提高农产品附加值,变资源优势为经济优势,并结合新疆区情,从多方面提出了新疆发展有机食品的思路和措施.     

室内有毒易爆气体的检测

随着城市生活水平的提高,室内装修装饰日益普及.各种新材料的引入,使得室内的各种有害气体总量日益增加.长期生活在这样的环境下,会对人体健康产生极为不利的影响.居民生活用煤气,在给人们生活带来便利的同时,作为一种可燃性、有毒气体,也具有极强的危害性.因此,研制一种能检测多种有害气体的实用仪器,具有很大的应用价值.本仪器为便携式多功能仪器,采用可充电电池供电,可以检测ppb的挥发性气体,显示气体浓度值,也可检测煤气,并具有声光报警功能.     

Trait space of rare plants in a fire‐dependent ecosystem

The causes of species rarity are of critical concern because of the high extinction risk associated with rarity. Studies examining individual rare species have limited generality, whereas trait‐based approaches offer a means to identify functional causes of rarity that can be applied to communities with disparate species pools. Differences in functional traits between rare and common species may be indicative of the functional causes of species rarity and may therefore be useful in crafting species conservation strategies. However, there is a conspicuous lack of studies comparing the functional traits of rare species and co‐occurring common species. We measured 18 important functional traits for 19 rare and 134 common understory plant species from North Carolina's Sandhills region and compared their trait distributions to determine whether there are significant functional differences that may explain species rarity. Flowering, fire, and tissue‐chemistry traits differed significantly between rare and common, co‐occurring species. Differences in specific traits suggest that fire suppression has driven rarity in this system and that changes to the timing and severity of prescribed fire may improve conservation success. Our method provides a useful tool to prioritize conservation efforts in other systems based on the likelihood that rare species are functionally capable of persisting.