Organic matter transport in an Appalachian Mountain river in Virginia,U.S.A.

Organic material transport in the New River, Virginia, was investigated over a 12 month period. Collections were made using drift nets and grab water samples from bridges at two sites about 210 km apart. About midway between the two sampling sites is a 1920 ha impoundment used for flood control and power generation. Dissolved organic matter (DOM) ranged 1–50 mg l^–1 at Site 1, upstream from the impoundment, and 11–19 mg l^–1 at Site 2 and was the most abundant form of organic matter at both sites during most periods of the year. Fine particulate organic matter (FPOM) ranged 1–45 mg l^–1 at Site 1 and 1–9 mg l^–1 at Site 2. Concentration of coarse particulate organic matter (CPOM) ranged 0.1–0.7 mg l^–1 at Site 1 and 0.1–0.2 mg l^–1 at Site 2. On an annual basis, the organic matter loads at Site 1 and Site 2 were computed to be 67 000 and 76 800 T y^–1, respectively, suggesting that the impoundment trapped and processed POM, and that municipal and industrial treatment facilities between the study sites supplemented DOM in the river.     

秸秆还田对土壤有机碳不同活性组分储量及分配的影响

通过田间试验,研究了不同秸秆还田模式下土壤溶解性有机碳(DOC)、颗粒有机碳(POC)和矿物结合有机碳(MOC)储量及其在总有机碳(TOC)中的分配比例.结果表明: 相对于翻压还田(WR),小麦秸秆覆盖还田(WM)0～20 cm耕层TOC和MOC储量显著降低,降幅为4.1%和9.7%,DOC和POC储量显著提高,增幅为207.7%和11.9%;20～40 cm犁底层TOC和POC储量显著提高.玉米秸秆覆盖还田(MM)与MR相比,犁底层TOC和MOC储量显著提高,增幅为13.6%和14.6%.小麦-玉米秸秆均覆盖还田(WM-MM)相对于均翻压还田(WR-MR),耕层TOC和MOC储量显著降低,降幅为8.5%和10.3%.玉米秸秆还田耕层TOC和POC储量显著高于小麦秸秆还田.与对照(秸秆不还田)相比,6种还田模式耕层TOC储量增幅为5.2%～18.0%,差异达显著水平;除WM和MM模式外,犁底层TOC储量显著降低(降幅8.0%～11.5%).6种还田模式下土壤耕层DOC储量及DOC/TOC比值显著降低,在WM和WM-MM还田模式下耕层POC储量显著提高、POC/TOC比值增大,WR模式的耕层MOC储量显著提高、MOC/TOC比值增大,其余3种模式耕层POC和MOC储量均显著提高.秸秆覆盖还田有利于土壤有机碳活性组分积累,翻压还田有利于较稳定性有机碳组分积累.在提高关中地区农田TOC储量方面,玉米秸秆还田好于小麦秸秆还田、小麦-玉米秸秆翻压还田好于覆盖还田.     

Differential gene expression of organic anion transporters in male and female rats.

Sex-related differential gene expression of organic anion transporters (rOAT1, rOAT2, and rOAT3) in rat brain, liver, and kidney was investigated. There were no sex differences in the expression of rOAT1 mRNA. rOAT2 mRNA was abundant in the liver and weakly expressed in the kidney of male rats; however, the OAT2 gene was strongly expressed in both organs of females. The abundance of rOAT2 mRNA markedly increased in castrated male rat kidney; however, treatment of castrated male rats with testosterone led to a decrease of rOAT2 mRNA. Expression of rOAT3 mRNA in intact female rats was found in the kidney and brain, whereas in males rOAT3 mRNA was also found in the liver. rOAT3 mRNA markedly decreased in the liver of castrated male rats but increased in testosterone-treated castrated male rats. Moreover, rOAT3 mRNA increased in the hypophysectomized female rat liver, indicating that rOAT3 is an inducible isoform. The present findings suggest that sex steroids play an important role in the expression and maintenance of OAT2/3 isoforms in the rat liver and kidney. Our results provide information on the differential gene expression of OAT isoforms with sex hormone dependency.     

森林流域坡面流与壤中流耦合模型的构建与应用

采用饱和入渗理论、Saint-Venant方程和Richards方程构建了以有限差分法求解的坡面流与壤中流耦合模型,并模拟了不同坡度和不同雨强下的坡面产汇流室内实验.结果表明：该模型模拟的坡面流和壤中流过程与实测过程基本一致,峰现时间、径流历时、峰值流量、出流总量模拟值与实测值的相对误差均较小,基本小于10%.模型的模拟精度较高,实用性较强,为深入研究壤中流机制和改进流域降雨-径流模型提供了理论依据.     

1997-2006年中国城市建成区有机碳储量的估算

随着城市区域碳排放的增加,城市碳循环在全球碳循环中的地位越来越重要,而城市碳排放和碳储量的估算是城市碳循环研究的基础.本研究利用统计资料,参考国内外相关研究成果,对1997-2006年中国城市建成区有机碳储量进行估算.结果表明： 1997-2006年,中国城市建成区总有机碳储量呈上升趋势,由0.13～0.19 Pg C（平均值为0.16 Pg C）增加到0.28～0.41 Pg C（平均值为0.34 Pg C）;建成区有机碳密度由9.86～14.03 kg C·m^-2（平均值为11.95 kg C·m^-2）增加到10.54～15.54 kg C·m^-2（平均值为13.04 kg C·m^-2）.建成区的有机碳主要储存在土壤中,其次是建筑物和绿地,居民有机体的碳储量可忽略不计.1997和2006年,土壤、建筑物、绿地和居民有机体在总碳库中的比例分别为78%、12%、9%、1%和73%、16%、10%、1%.     

TOC, TON, TOS and TOP in Rainfall, Throughfall, Litter Percolate and Soil Solution of a Montane Rainforest Succession at Mt. Kilimanjaro, Tanzania

Organic nutrients have proven to contribute significantly to nutrient cycling in temperate forest ecosystems. Still, little is known about their relevance in the tropics. In the present study, organic C, N, S and P were analysed in rainfall, throughfall, litter percolate and soil solution of a montane rainforest at Mt. Kilimanjaro, Tanzania. The aim was to determine the amounts of organic nutrients in different water pathways and to assess the influence of forest disturbance on organic nutrients by comparing mature forests, secondary forests and shrub vegetation in clearings. Concentrations of all studied elements increased from rainfall to throughfall and litter percolate and then exhibited a rapid decrease in the mineral soil. Concentrations of organic P were above the detection limit only in the litter percolate. Organic N (ON) as a fraction of total N increased from 50% in rainfall (0.19 mg l⁻¹) to 66% (0.45 mg l⁻¹) in throughfall followed by a decline to 39% in the litter percolate (0.77 mg l⁻¹) of the mature forest. Similarly, proportions of organic S and P amounted to 43 and 34%, respectively, in the litter percolate in mature forest. For ON, this proportion further decreased to less than 10% in the soil solution. The latter was probably attributable to a high sorption capacity of the studied Andisols, which led to overall low organic element concentrations in the soil solution (OC: 1.2 mg l⁻¹, ON: 0.05 mg l⁻¹ at 1 m soil depth) as compared to other temperate and tropical forest ecosystems. Organic element concentrations were higher in litter percolate and soil solution under the clearings, but there were no differences in the relative contribution of these elements. Organic nutrient forms at Mt. Kilimanjaro appeared to be much less susceptible to leaching than their inorganic forms.     

重金属污染对土壤有机质积累的影响

采用田间采样分析与室内培养试验相结合的方法,研究了不同重金属污染土壤中有机质积累的差异及重金属污染强度对土壤有机质矿化动态变化的影响.结果表明：污染土壤中重金属的大量积累可减弱有机物质的矿化速率,增加土壤有机质的积累.土壤中颗粒态有机质及其占总有机碳的比例随重金属积累的增加而增加;而微生物生物量碳占总碳的比例却随土壤重金属污染水平的提高而下降.污染土壤中颗粒态有机质对重金属有显著的富集,这可能是影响土壤有机物质进一步矿化的原因之一.重金属污染可改变土壤有机质的矿化速率,影响土壤有机质的积累与分配.     

不同冬季覆盖作物对双季稻田土壤有机碳的影响

以冬闲-双季稻种植模式为对照(CK),分析了黑麦草-双季稻(Ry)、紫云英-双季稻(Mv)、马铃薯-双季稻(Po)和油菜-双季稻(Ra)5种不同种植模式下冬季覆盖作物秸秆还田后对0～5、5～10、10～20 cm土壤有机碳、活性有机碳、碳库管理指数和有机碳储量的影响.结果表明:与CK处理相比,黑麦草、紫云英、马铃薯和油菜秸秆还田处理均提高了稻田0～5、5～10、10～20 cm土壤总有机碳和活性有机碳含量,其中Po处理最高.冬季覆盖作物秸秆还田均提高了稻田不同层次土壤的碳库活度、碳库活度指数、碳库指数和土壤碳库管理指数,其大小顺序均表现为Po>Mv>Ry>Ra>CK.不同冬季覆盖作物秸秆还田处理与CK处理相比均有利于提高稻田不同层次土壤有机碳储量,其中以紫云英秸秆还田的效果最好,黑麦草和马铃薯次之;各处理稻田土壤有机碳储量均随土壤深度的增加而递增.     

青岛近海及其临近海域冬季微微型浮游植物的分布

微微型浮游植物（0.2～2.0 μm） 是海水中最小的自养浮游生物, 在世界各海域广泛分布, 并在海洋有机物质循环中起着非常重要的作用.利用荧光显微技术对青岛近海及其邻近海域冬季微微型浮游植物丰度进行了调查,研究了微微型浮游植物的空间变化和昼夜变化的特征, 并分析了微微型浮游植物丰度与环境因子的相关性. 结果显示, 冬季该海域以富含藻红素（Phycoerythrin-rich, PE）的聚球藻(Synechococcus, Syn)细胞占优势,微微型真核藻类（Picoeukaryote, Euk）次之,而富含藻蓝素（Phycocyanin-rich, PC）的聚球藻细胞数量很低, 未发现原绿球藻（Prochlorococcus, Pro）的存在.Syn 的变化范围为8.97×10³～1.95×10⁵ cells·ml^-1, 平均4.67×10⁴ cells·ml^-1; Euk的变化范围为1.95×10²～1.01×10⁴ cells·ml^-1, 平均2.39×10³ cells·ml^-1. Syn丰度在胶南以南海域出现高值区域, 在即墨海域和崂山东南海域出现低值区域. Euk丰度在日照海域出现高值区域; 崂山海域为低值区域; 各水层Syn和Euk丰度均无明显差异(P﹥0.05). 对胶州湾中部连续站4层水体的24 h昼夜连续变化进行观测发现, Syn、Euk丰度都有明显昼夜波动.相关性分析表明： Syn与温度、 电导率呈正相关, 与溶氧浓度呈显著负相关; Euk与盐度和溶氧浓度呈显著负相关. 微微型浮游植物对总浮游植物生物量的贡献约为20％.     

论有机肥料在农业生态系统中的地位和作用

人类为了生存,要从自然界取走一些物质和能量,并以不同的形式将物质和能量归还给自然即生态系统。要维持自然生态系统的动态平衡,“取走”和“归还”必须保持永续和相对     

火烧迹地不同恢复方式土壤有机碳分布特征

以大兴安岭1987年重度火烧后恢复的兴安落叶松人工林、樟子松人工林、人促杨桦林和天然次生杨桦林为对象,研究不同恢复方式林分土壤有机碳、土壤可溶性有机碳和土壤微生物生物量碳的分布特征.结果表明: 4种恢复方式林分的土壤有机碳、土壤可溶性有机碳和土壤微生物生物量碳分别为9.63～79.72 g·kg^-1、33.21～186.30 mg·kg^-1和200.85～1755.63 mg·kg^-1,且随土层深度增加而降低.不同恢复方式间土壤有机碳、土壤可溶性有机碳和土壤微生物生物量碳差异显著,以人促杨桦林最高,兴安落叶松人工林和天然次生杨桦林次之,樟子松人工林最低.各恢复方式林分的土壤微生物熵为1.1%～2.3%,以人促杨桦林最高,樟子松人工林最低,不同林分土壤微生物熵的垂直分布特征不同.土壤微生物生物量碳与土壤有机碳、土壤可溶性有机碳含量均呈显著正相关.人促杨桦林土壤有机碳活性高于其他林分,火烧迹地采用人工促进天然恢复的方式较人工恢复和天然恢复的土壤碳循环能力更强.     

滨海电厂冷却水余热和余氯对中华哲水蚤的影响

依据滨海电厂冷却系统的实际运作情况,模拟研究了滨海电厂冷却水余热和余氯对中华哲水蚤的影响.结果表明：中华哲水蚤的热忍受能力随暴露时间延长而降低,随驯化温度升高而升高.驯化温度为16 ℃～27 ℃的中华哲水蚤在持续受到15、30、45 min热冲击及持续升温暴露24和48 h的致死温度分别为29.9 ℃～31.7 ℃、29.4 ℃～31.0 ℃、28.9 ℃～30.3 ℃和26.9 ℃～28.5 ℃、26.4 ℃～28.0 ℃.当驯化温度升高到一定程度后,其热忍受能力不再上升.电厂冷却水中余氯对中华哲水蚤的毒性随驯化温度升高、升温幅度增大及暴露时间延长而增强.     

亚热带杉木林土壤有机碳及其活性组分对氮磷添加的响应

通过野外氮、磷添加,分析N₀(0 kg N·hm^-2·a^-1)、N₁(50 kg N·hm^-2·a^-1)、N₂(100 kg N·hm^-2·a^-1)、P(50 kg P·hm^-2·a^-1)、N₁P和N₂P等6种处理3年后对亚热带杉木人工林土壤有机碳(SOC)、颗粒有机碳(POC)和水溶性有机碳(WSOC)的影响.结果表明:氮、磷添加对0～20 cm土层SOC含量无显著影响.磷添加显著降低0～5 cm土层POC含量,与无磷处理相比,加磷处理POC含量降低26.1%.WSOC含量对氮、磷添加的响应主要表现在0～5 cm土层,低水平氮添加和磷添加显著提高WSOC含量.在0～5 cm土层,氮添加对POC/SOC值无显著影响,而与无磷添加相比,POC/SOC值在磷添加处理下显著降低15.9%.在5～10和10～20 cm土层,氮、磷添加处理对POC/SOC值无显著影响.在亚热带地区,森林土壤碳稳定性主要受磷含量的调控,短期磷添加易导致表层土壤活性有机碳分解,增加土壤碳稳定性.     

华南典型树种凋落叶的野外分解和溶解性有机质溶出动态

选用华南亚热带地区常见阔叶树种木荷和针叶树种湿地松的新近凋落叶,在野外分解0、30、60、90、150、210、240、365 d,分析溶出的溶解性有机质(DOM)浓度、组成和性质的变化,以及对土壤可溶性有机碳(DOC)的影响.结果表明: 随着分解的进行,尽管木荷叶片的DOM浓度高于松针,但是2种凋落叶DOM浓度、性质和物质组成变化规律一致;2种凋落叶的DOM浓度均呈下降趋势,芳香化程度和分子量增大,富里酸、腐殖酸类物质逐渐增多,可降解的简单芳烃蛋白(如酪氨酸)逐渐减少.在分解初期,DOM主要由亲水中性和酸性部分组成,易分解、易迁移,对表层土壤DOC影响不显著;在分解后期,DOM主要为腐殖酸和富里酸类物质,吸附性强,表层土壤DOC浓度显著下降.