施用生物炭对麦田土壤细菌群落多样性和冬小麦生长的影响

通过长期田间定位试验研究土壤细菌群落的多样性及作物生长对施用生物炭的响应,为生物炭在农田中的合理应用提供科学依据.以冬小麦为研究对象,设置生物炭施加量为0(B0对照)、 5(B1)、 10(B2)和20 t·hm^-2(B3)这4个处理,结合Illumina MiSeq高通量测序技术探究不同生物炭施用量对冬小麦扬花期和成熟期土壤理化性质、土壤细菌群落多样性和作物生长的影响.结果表明,土壤含水量、 pH值、土壤有机碳、全氮、硝态氮含量、冬小麦生物量、氮吸收和产量随着生物炭施用量的增加均表现出增加趋势.高通量测序结果得出B2处理显著降低了扬花期细菌群落α多样性;土壤细菌群落组成对不同施用量的生物炭和物候期的总体响应在分类上一致,本研究以变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、浮霉菌门(Planctomycetes)、芽单胞菌门(Gemmatimonadetes)和放线菌门(Actinobacteria)为优势菌门(相对丰度>5%),酸杆菌门的相对丰度下降,但随着生物炭的施用,变形菌门和浮霉菌门的相对丰度增加.冗余分析、共现...     

白洋淀冬季沉积物好氧反硝化菌垂向分布特征及群落构建

为了探究白洋淀冬季沉积物好氧反硝化菌群落垂向分布特征、关键物种和群落构建过程,结合好氧反硝化功能基因（napA）高通量测序技术,进行了微生物多样性分析、物种差异分析、关键物种识别和群落构建过程研究.结果表明,该时期白洋淀沉积物高通量测序得到13 845个OTUs,共分为10个门类,其中第一大门类为变形菌门,达到29.03%～94.46%,从表层到底层呈下降趋势;占比前二的纲为β-Proteobacteria和γ-Proteobacteria;占比前三的属为Cupriavidus、Aeromonas和Thauera.微生物α多样性显示垂向分组间表层沉积物Chao1指数最大为3 327.67±621.28,明显高于底层（2 193.96±455.57）;中层沉积物Simpson指数最大为0.97±0.013,明显高于表层（0.94±0.029）.主成分分析和Venn图显示表层和底层间差异性最显著,Adonis分析表明垂向间存在极其显著差异（P<0.001）;随机森林分析和网络分析的关键物种有交叉相同的物种（Bordetella）,但差异贡献程度最高的物种不同,分别为Ferrimona...     

紫外辐射增强对麦二叉蚜发生量的影响

研究春小麦大田栽培自然光条件下,模拟紫外辐射（ＵＶ－Ｂ,２９０￣３１５ｎｍ）分别增加２．５４、４．２５及５．３１ｋＪ·ｍ＾－２对小麦（寄生虫麦二叉蚜（Ｓｃｈｉｚａｐｈｉｓ ｇｒａｍｉｎｕｍ）的发生、种群密度、繁殖系数等方面的影响。结果表明麦二叉蚜的种群密度与其当年的发生量密切相关,并且种群密度随着ＵＶ－Ｂ辐射强度的增加明显降低,但对麦二叉蚜的繁殖特性没有显著的抑制作用。因此认为,未来臭氧层减薄紫外     

UV-B辐射增强与O3胁迫对冬小麦光合特征的影响

为探明UV-B和O3复合胁迫对冬小麦光合作用的影响,开展了UV-B和O3单因子及其复合的大田开顶式气室（OTC）试验（CK,自然空气和UV-B辐射强度;T1,O3含量100 nmol.mol-1±9 nmol.mol-1;T2,UV-B辐射强度相对CK增加10%～10.9%;T3,复合处理组）,利用LCpro＋光合仪和...     

等碳量添加秸秆和生物炭对土壤呼吸及微生物生物量碳氮的影响

为探究土壤呼吸、土壤微生物生物量碳氮及水热因子对生物炭和秸秆添加的响应,采用LI-8100 土壤碳通量测量仪(LI-COR,Lincoln,USA)测定了常规施肥(CK)、常规施肥+2.25 t·hm-2生物炭-C(T1)、常规施肥+2.25 t·hm-2秸秆-C(T2)、常规施肥+1.125 t·hm-2生物炭-C+...     

碱性土壤锌镉比对小麦籽粒镉积累的影响

我国北方地区小麦镉(Cd)污染形势严峻.土壤锌(Zn)与Cd存在显著的交互作用,但两者关系尚不明确.本研究通过区域调查及大田实验,探究了北方碱性小麦土壤锌镉比(Zn/Cd)与小麦籽粒Cd含量的相关关系.结果表明,土壤Zn/Cd与小麦籽粒Cd含量显著负相关.施加硫酸锌(增Zn)及深翻耕措施(降Zn)均能显著提高土壤Zn/Cd,并降低小麦籽粒Cd含量.其中,增施100 mg·kg^-1的Zn²⁺,可将土壤Zn/Cd增加61.2%,并使小麦籽粒Cd含量降低9.28%;将土壤0~30 cm及30~60 cm土层互换的深翻耕措施,可将土壤Zn/Cd增加45.8%,并使小麦籽粒Cd含量降低13.5%.综合区域调查及大田实验数据,发现当土壤Zn/Cd小于50时,小麦籽粒Cd含量全部超标且有98.4%的样品超标1倍以上;而当土壤Zn/Cd大于100时,小麦籽粒Cd含量超标风险显著降低至11.9%.该阈值的确定对于小麦Cd污染防治具有指导意义.     

Effects of ground-level ozone (O3) pollution on the yields of rice and winter wheat in the Yangtze River Delta

Effects of elevated O3 on the yields of rice and winter wheat were studied by using open-top chambers(OTCs).Results showed that compared to the control treatment,200 ppb,100ppb,50ppb treatments caused a 80.4%,58.6%and 10.5% decrease in grain yields per winter wheat plant and a 49.1%,26.1% and 8.2% decrease in grain yield per rice plant,respectively.According to the dose-response relation educed from OTCs experiment and the monitor data of O3 concentrations in spots,it was estimated that the yield losses of rice and winter wheat resulted by O3 pollution in the Yangtze River Delta region in 1999 were 0.599 million ton and 0.669 million ton,economic losses were 0.539 billion RMB Yuan and 0.936 billion RMB Yuan,respectively.     

冬季净化湖水的效果与机理

为了做到全年改善饮用水水质,需要研究在冬季怎样有效净化水质的问题为此,在太湖重富营养化水域进行了人工生态系统工程改进试验．结果表明,采用若干措施后,能大大地改善水质;滞留时间<2d时,工程内净化效果不明显;滞留时间延至7d左右时,水质指标能改善50％－80％;工程内水质净化的机理为高等水生植物及其共生细菌的共同作用,使人工生态系统工程成为抵抗环境变化的稳定生态系统,使水质变化处于良性循环;而滞留时间<2d或在人工生态系统工程外,水质变化处于恶性循环     

北京市核心区冬春季大气离子沉降量特征及来源解析

近年来生态环境部和北京市不断加严降尘量控制指标,为了掌握降尘量中离子沉降量特征及其来源,采用过滤法和离子色谱法分别测定北京市核心区冬春季降尘量及离子沉降量,采用PMF模型开展离子沉降量来源解析.结果表明：(1)离子沉降量及其在降尘量中占比平均值分别为0.87 t·(km²·30 d)^-1和14.2%,工作日降尘量和离子沉降量分别是休息日的1.3倍和0.7倍.(2)离子沉降量与降水量、相对湿度、温度和平均风速的线性方程可决系数分别为0.54、 0.16、 0.15和0.02,离子沉降量与PM_2.5浓度和降尘量的线性方程可决系数分别为0.26和0.17,控制PM_2.5浓度对控制离子沉降量非常重要.(3)离子沉降量中阴、阳离子分别占61.6%和38.4%,SO^2-₄、 NO^-₃和NH⁺₄合计占60.6%;阴阳离子电荷沉降量比值为0.70,降尘呈碱性;离子沉降量中ρ(NO     

Ecological responses to variation in seasonal snow cover

Seasonal snow is among the most important factors governing the ecology of many terrestrial ecosystems, but rising global temperatures are changing snow regimes and driving widespread declines in the depth and duration of snow cover. Loss of the insulating snow layer will fundamentally change the environment. Understanding how individuals, populations, and communities respond to different snow conditions is thus essential for predicting and managing future ecosystem change. We synthesized 365 studies that examined ecological responses to variation in winter snow conditions. This research encompasses a broad range of methods (experimental manipulations, measurement of natural snow gradients, and long-term monitoring), locations (35 countries), study organisms (plants, mammals, arthropods, birds, fish, lichen, and fungi), and response measures. Earlier snowmelt was consistently associated with advanced spring phenology in plants, mammals, and arthropods. Reduced snow depth often increased mortality or physical injury in plants, although there were few clear effects on animals. Neither snow depth nor snowmelt timing had clear or consistent directional effects on body size of animals or biomass of plants. However, because 96% of studies were from the northern hemisphere, the generality of these trends across ecosystems and localities is also unclear. We identified substantial research gaps for several taxonomic groups and response types; research on wintertime responses was notably scarce. Future research should prioritize examination of the mechanisms underlying responses to changing snow conditions and the consequences of those responses for seasonally snow-covered ecosystems.