Short chain nitrocompounds as a treatment of layer hen manure and litter; effects on in vitro survivability of Salmonella,generic E. coli and nitrogen metabolism

The current study was conducted to assess the bactericidal effectiveness of several nitrocompounds against pathogens in layer hen manure and litter. Evidence from an initial study indicated that treatment of layer hen manure with 12 mM nitroethane decreased populations of generic E. coli and total coliforms by 0.7 and 2.2 log₁₀ colony forming units (CFU) g^?1, respectively, after 24 h aerobic incubation at ambient temperature when compared to untreated populations. Salmonella concentrations were unaffected by nitroethane in this study. In a follow-up experiment, treatment of 6-month-old layer hen litter (mixed with 0.4 mL water g^?1) with 44 mM 2-nitroethanol, 2-nitropropanol or ethyl nitroacetate decreased an inoculated Salmonella typhimurium strain from its initial concentration (3 log₁₀ CFU g^?1) by 0.7 to 1.7 log₁₀ CFU g^?1 after 6 h incubation at 37°C in covered containers. After 24 h incubation, populations of the inoculated S. Typhmiurium in litter treated with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate or nitroethane were decreased more than 3.2 log₁₀ CFU g^?1 compared to populations in untreated control litter. Treatment of litter with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate decreased rates of ammonia accumulation more than 70% compared to untreated controls (0.167 µmol mL^?1 h^?1) and loses of uric acid (< 1 µmol mL^?1) were observed only in litter treated with 44 mM 2-nitropropanol, indicating that some of these nitrocompounds may help prevent loss of nitrogen in treated litter. Results warrant further research to determine if these nitrocompounds can be developed into an environmentally sustainable and safe strategy to eliminate pathogens from poultry litter, while preserving its nitrogen content as a nutritionally valuable crude protein source for ruminants.     

猪场生物发酵床垫料卫生研究

通过选择有3个采用发酵床养猪模式的猪场,采集不同使用年限、不同深度及饲养不同阶段猪舍的发酵床垫料,通过测定水分、总N、总P、可溶性盐、黄曲霉毒素B1(AFB1)、枯草芽孢杆菌和大肠杆菌数目、Cu和Zn含量(全重金属及有效态重金属)评估垫料的卫生学状况.并将垫料与土壤以不同比例混合,研究对植物生长及Cu、Zn在植株中残留影响.研究表明,发酵床垫料随着深度增加,垫料的水分含量逐渐降低,温度逐渐升高,大肠杆菌、枯草芽孢杆菌数量减少.随着发酵床使用年限的延长,总N随垫料使用时间延长而变低,而总P含量随时间延长而增加,但变化均不显著(P＞0.05);Cu、Zn、Pb、可溶性盐含量都呈现显著的增加(P＜0.05).在1年、2年、3年期的垫料中AFB1均有检出,含量均小于10 μg/kg.种植实验结果显示,土壤添加垫料后,Cu、Zn含量随着添加比例增加而增加,植物中残留量随着垫料添加比例的增加而增加.因此在处理发酵床垫料时,要综合考虑其对环境及食品安全的影响.     

Methyl chloride emissions from halophyte leaf litter: dependence on temperature and chloride content

Methyl chloride (CH₃Cl) is the most abundant natural chlorine containing compound in the atmosphere, and responsible for a significant fraction of stratospheric ozone destruction. Understanding the global CH₃Cl budget is therefore of great importance. However, the strength of the individual sources and sinks is still uncertain. Leaf litter is a potentially important source of methyl chloride, but factors controlling the emissions are unclear. This study investigated CH₃Cl emissions from leaf litter of twelve halophyte species. The emissions were not due to biological activity, and emission rates varied between halophyte species up to two orders of magnitude. For all species, the CH₃Cl emission rates increased with temperature following the Arrhenius relation. Activation energies were similar for all investigated plant species, indicating that even though emissions vary largely between plant species, their response to changing temperatures is similar. The chloride and methoxyl group contents of the leaf litter samples were determined, but those parameters were not significantly correlated to the CH₃Cl emission rate.     

施氮与凋落物去除影响下中亚热带阔叶林土壤氮素矿化潜势和硝化潜势研究

氮沉降影响土壤氮循环,而凋落物是土壤有机氮的主要来源,因此,为了探讨氮沉降和凋落物是否去除作用下,亚热带森林土壤潜在的氮素矿化与硝化作用,选择已进行8年模拟氮沉降试验的亚热带罗浮栲(Castanopsis fabri)常绿阔叶林土壤为研究对象,野外样地氮添加设置3个水平:对照(CK,0 kg·hm?2·a?1)、低氮(...     

川西亚高山针叶林人工恢复过程的土壤性性质变化

研究川西岷江上游高山针叶林区不同年龄阶段的人工云杉林地凋落物及其养分贮量和土壤养分及主要理化性质的变化趋势,结果表明：（1）人工云杉林的凋落物及其氮、磷、钾贮量、以60年代抚育成熟林最高,40年代抚育成熟林大幅度下降,分别下降34．1％及49．8％,70．5％,46．7％;（2）人工云杉林地表土的有机质、全氮、全磷随林龄的增加而降低,据典型土壤剖面资料,40年代比60年代抚育林土壤分别降低72．4％,78．6％,42．2％;（3）相应于土壤有机质的变化,与60年代人工云杉成熟林相比,40年代成熟林土壤的自然含水量、总孔工、保肥力（CEC）和交换性盐某养分等均明显降低,表现出肥力退化的趋势,因此,当人工云杉林达到成熟林后,后采取诸如适当间伐等措施,以改善林地生态条件,避免土壤肥力退化,图4表6参11。     

岷江上游高山森林凋落叶在冬季河流中的质量损失特征

凋落叶在高山森林河流中的分解不仅是生态系统物质循环的重要内容,而且与森林养分流失以及下游水体环境密切相关,并可能受到冬季雪被变化和土壤季节性冻融的影响,但一直缺乏必要的关注。因此,以岷江上游高山森林4种代表性植物康定柳(Salix paraplesia)、高山杜鹃(Rhododendron lapponicum)、方枝柏(Sabina saltuaria)和四川红杉(Larix mastersiana)凋落叶为研究对象,采用凋落叶分解袋法,研究了一个冬季不同冻融时期(冻结初期、冻结期和融化期)的质量损失特征。经过一个冬季(162d)的分解,康定柳、高山杜鹃、方枝柏和四川红杉凋落叶分别完成了初始干重45.5%、18.9%、26.4%和23.8%的分解;除康定柳凋落叶质量损失在融化期最大外,其余3种凋落叶均表现为冻结初期最大;康定柳、方枝柏和四川红杉凋落叶质量损失与河流水环境的平均温度和正积温均表现出显著或极显著的正相关关系,且与河流流速和硝态氮显著正相关,而与河流pH显著负相关;高山杜鹃凋落叶质量损失除与HCO3-含量显著相关外,与河流水温及其它水质特征均无显著相关关系。这些结果表明高山森林河流流速及水环境特征显著影响了凋落叶分解及其相关的物质循环过程,但影响程度受到凋落叶特性的调控。     

What is left behind when the lights go off? Comparing the abundance and composition of litter in urban areas with different intensity of nightlife use in Mar del Plata,Argentina

Nightlife activities represents an important source of urban litter; the latter often being left behind or abandoned in public places and streets. Mar del Plata is a very important city on the Atlantic coast of Argentina and is the main tourism destination in the South Atlantic region of South America. However, few studies on urban litter related to nightlife activities have been conducted in the area. Here we assessed (i) the abundance and composition of litter, and (ii) the spatial and temporal variations of its abundance, diversity, richness and evenness in urbanized areas with different intensity of nightlife activities from April 2008 to March 2009. An overall of 13,503 items were counted. Around 92% of the total litter was comprised by cigarette butts, papers and plastics. We found significant spatial differences in the abundance of litter between sampling sites, with the greatest amounts of litter at the Alem site followed by the Hipólito site (both with an intensive nightlife activity) compared with the Chauvin site (a quiet high-income neighborhood). The composition of litter of the Alem and the Hipólito sites was relatively similar and both sites differ with respect to the Chauvin site. Cigarette butts, papers, and plastics were the items that contributed most to the dissimilarity between sampling sites. The diversity of litter was the single community parameter that significantly differed from the other seasons. We discussed the potential effect of nightlife activities on the amounts and quality of urban litter in the city of Mar del Plata.     

PCR-DGGE技术解析针叶和阔叶凋落物混合分解对土壤微生物群落结构的影响

为深入理解凋落物类型和微生物群落之间的相互关系,通过小盆+凋落袋控制实验,运用PCR-DGGE技术解析了南方红壤丘陵区典型针叶树种马尾松和湿地松的凋落物分别与白栎、青冈两个阔叶树种凋落物混合分解对土壤微生物基因型多样性的影响.结果表明:1)针叶凋落物中加入阔叶后细菌群落结构未发生显著变化,将所有处理归为一类的相似度达72%,其差异仅表现在马尾松+白栎和湿地松+青冈处理土壤微生物群落16S rDNA的丰富度和多样性分别显著高于单一马尾松和湿地松;2)针叶凋落物中加入阔叶后真菌群落结构发生了显著变化,单一针叶处理与针阔混合处理间18S rDNA基因泳道带型的相似度只有28%,并且单一马尾松处理土壤18S rDNA的丰富度和多样性显著高于马尾松+白栎和马尾松+青冈,单一湿地松处理土壤18S rDNA的丰富度也显著高于湿地松+白栎和湿地松+青冈,多样性显著高于湿地松+白栎处理;3)土壤真菌18S rDNA的丰富度与凋落物初始C含量呈显著正相关,与凋落物初始N含量呈显著负相关.针叶凋落物中引入阔叶凋落物后,增加了凋落物中N的比重,C的比重则下降,显著影响了土壤真菌群落的结构.     

四姑娘山国家级自然保护区3种典型植被类型水源涵养功能研究

通过对四姑娘山自然保护区四川红杉林、岷江冷杉林、中国沙棘林3种典型植被类型林下枯落物的实验分析,四姑娘山自然保护区内四川红杉林、岷江冷杉林、中国沙棘林林下枯落物数量、持水能力要高于一般的针叶林和阔叶林,四川红杉林、岷江冷杉林、中国沙棘林林下枯落物最大持水率差异不显著(P=0.080)。LSD多重比较结果可知,中国沙棘林最大持水率显著高于岷江冷杉林、四川红杉林,而岷江冷杉林、四川红杉林间最大持水率差异不显著。     

高山森林溪流凋落叶冬季水溶性碳含量动态

凋落物分解过程中水溶性碳是高山森林溪流生态系统碳的重要来源,其在溪流中的流动转移不仅会影响下游水质环境,而且其含量动态受冬季季节性雪被形成及消融过程的深刻影响,但缺乏必要关注.因此,采用凋落叶分解袋法,以川西高山森林典型乔木(四川红杉Larix mastersiana、方枝柏Sabina saltuaria)和灌木(高山杜鹃Rhododendron lapponicum、康定柳Salix paraplesia)凋落叶为研究对象,根据凋落叶自然分解规律,研究冬季不同时期(冻结初期、冻结期、融化期)河流、溪流、河岸带以及林下凋落叶水溶性碳以及可溶性组分含量格局的动态变化特征.结果表明:在冬季的分解过程中,冻结初期河流与溪流中凋落叶水溶性碳与可溶性组分含量显著降低,而至冻结期与融化期含量均无明显变化.各时期,林下凋落叶水溶性碳和可溶性组分含量显著高于其他生境,表现为从河流、溪流、河岸带至林下逐渐增加的变化趋势.相关分析表明,高山森林凋落叶分解过程中水溶性碳和可溶性组分含量与平均温度、正积温、负积温以及流速均呈极显著负相关关系,同样也受到PO3-4和p H等水环境因子的影响.可见,高山森林凋落叶冬季水溶性碳和可溶性组分在分解过程中易随水体的流动而向下游生态系统输出,这为深入认识高山森林-流域水体间的生态联系提供了一定的科学依据.