设施菜地土壤重金属累积及影响因素研究

为了解设施菜地土壤重金属累积规律及影响因,通过在全国8个省具有代表性的设施蔬菜产区采集土壤和肥料样品,系统研究了设施栽培年限、肥料施用、土壤性质对设施菜地土壤重金属Cu、Zn、Cd累积量及活度的影响.结果表明:与露天栽培相比,设施条件下随着栽培年限的延长,土壤Cu、Zn和Cd的全量和有效态浓度均呈明显的累积趋势,栽培年限>15a时的设施土壤Cu、Zn和Cd的全量和有效态浓度分别是露天栽培土壤的1.57、2.16、1.67、3.28、1.96、2.00倍.Pearson分析表明设施菜地土壤Cu、Zn、Cd均与土壤SOM呈极显著相关,说明其在来源上较强的相似性,进一步对设施栽培土壤主要投入品中Cu、Zn、Cd含量分析表明,猪粪、商品有机肥及土壤调理剂中Cu、Zn均超过了100mg/kg,Cd超过了1.0mg/kg,且投入量较大,是设施栽培土壤中Cu、Zn、Cd的主要贡献者,而秸秆和部分化肥(如尿素、硫酸钾)中的Cu、Zn、Cd含量均极低,对设施栽培土壤累积贡献微乎其微.pH值和CEC是影响Cu、Zn、Cd在土壤中累积活度的关键因素,其中随着pH值的升高土壤Cu活度表现了先升高后下降的趋势,而土壤Cd活度则表现了持续下降的趋势,仅在pH<6.26时达到了显著相关水平;土壤CEC的升高对土壤Cu活度表现了先下降后升高再下降的趋势,土壤Cd活度表现了先升高后缓慢下降再升高的趋势,而土壤Zn活度仅在CEC<5.83时随着CEC升高表现下降显著线性相关趋势.因此,防止设施栽培土壤Cu、Zn、Cd的累积与污染,选择重金属含量低的肥料和调控土壤理化特性(尤其是pH值、CEC)则是缓解设施栽培土壤重金属累积速率进而确保蔬菜质量安全的有效途径.     

设施农业土壤磷素累积迁移转化及影响因素

为了科学合理施用磷肥,减小对设施农业环境带来的污染风险,以北京市大兴区设施农业集中区为研究对象,通过对不同种植年限设施农业剖面土壤(0～100 cm)磷素含量的测定分析,探究磷素累积与迁移转化特征.结果表明,设施农业表层土壤全磷和有效磷含量变化范围大,显著高于周边粮田土壤,主要跟不同种植年限农户的施磷量相关,随着土层深度的增加,全磷和有效磷含量逐渐减小,呈现表聚特征,其中土壤ω(全磷)范围在0.38～2.58 g·kg^-1,ω(有效磷)范围在1.60～256.00 mg·kg^-1.随着种植年限的增加,土壤全磷和有效磷含量呈现先增加后减小的趋势,在15 a左右达到峰值,随后逐渐减少,趋于稳定,总体处于较高水平.无机磷主要集中在设施农业表层土壤,其中Ca-P占无机磷的比例最大,达到了98.38%,Ca₁₀-P是最主要的Ca-P形态,含量占Ca-P的78.70%,Ca₂-P占比最小,仅占9.50%.不同形态无机磷含量呈现表层土壤富集,向下减少的垂直分布特征;不同土层深度,不同形态无机磷占全磷比例变化存在差...     

黄土丘陵区不同恢复植被类型的固碳特征

为分析黄土高原水土流失严重区不同恢复植被类型的固碳特征,比较恢复年限和坡向因素对植被碳汇效应的影响,在陕北黄土丘陵区选取了6种典型植被类型（农地、草地、沙棘、柠条、刺槐和山杨）,研究了不同类型的生态系统碳密度及其构成特征.结果表明：①半干旱黄土区植被恢复具有明显的碳汇功能,不同植被组分（地上生物、地下根系和枯落物）碳密度均表现出乔木>灌丛>草地>农地的变化特征.农地0~40 cm土层土壤有机碳密度最低（1355.5 g ·m^-2）,草地、沙棘、柠条、刺槐和山杨较农地分别增加了91.4%、125.2%、144.0%、124.5%和232.6%.②草地、沙棘、柠条和山杨的不同植被组分碳密度和不同土层（0~5、5~20和20~40 cm）土壤有机碳密度随恢复时间的推移总体上表现出增加趋势.③坡向对农地和草地植被碳密度无明显影响,沙棘、柠条、刺槐和山杨不同坡向间的植被碳密度差异明显.土壤有机碳密度存在明显的阴阳坡差异,农地、草地、沙棘、柠条、刺槐和山杨阳坡土壤有机碳密度分别比阴坡减少了22.9%、34.3%、75.8%、49.1%、22.4%和69.4%.④不同类型的生态系统碳密度差异明显,其中农地最低（2022.1 g ·m^-2）,草地、沙棘、柠条、刺槐和山杨较农地分别增加了48.7%、152.8%、125.1%、166.3%和530.7%.生态系统各组分碳密度总体表现为：土壤层>地上生物层>根系层>枯落物层.土壤有机碳构成了农地、草地、沙棘、柠条和刺槐碳密度的主体,分别占生态系统碳密度的67.0%、86.3%、59.7%、72.7%和56.5%.研究结果可为黄土高原地区科学管理生态系统碳库和推进生态环境治理提供重要依据.     

Organic farmers in islands: Agricultural management and attitude towards the environment

SUMMARY

This study explores differences among organic farmers who live in islands and have isolated small-size operations. The relationships between farmers' characteristics and attitudes and farm management were interpreted by studying how they manage their land, their attitudes towards the environment and alternative farming systems, and their involvement in organic farming. The research was carried out using questionnaires addressed to organic farmers on the island of Thassos. Nonlinear canonical correlation was applied for data analysis. This information could contribute to adjustment of policy decisions for on-farm diversification. Agricultural policy makers should approach organic farmers in northern Thassos (productive irrigated olive orchards with gentle slopes) by enacting standards to reduce the cost of alternative plant protection methods and promoting their products in order to maintain and expand organic farming. They should also approach organic farmers in southern Thassos (less productive, dry cultivated olive orchards with steep slopes, overgrazed and often abandoned) by providing them with the necessary information and appropriate agricultural know-how to effectively manage their farms. Organic farmers with stable off-farm income are more aware of environmental values and consider that they risk less than others in order to gain the benefits of alternative farming systems. However, they should attend training programmes to achieve economic success to allow them to continue farming organically.     

Risk assessment of Giardia in rivers of southern China based on continuous monitoring

The occurrence and risks of Giardia in China have been unclear to date, which has made it difficult to properly manage source water as well as to create reasonable drinking water standards. The levels of Giardia in river networks of several cities in Zhejiang Province, China were found to be in the range of 0-5 oocysts/10 L in the rainy season in 2008. The mortality due to Giardia infection for people in this region was calculated to be from 0 to 1.95 × 10^-8 persons using a conditional probability equation. Based on multiple unboiled water intake routes, the disability-adjusted life years (DALYs) due to Giardia infection for people who consumed conventionally treated water was 0.625 (95% CI: 0.137-2.05) per 10⁵ persons, with the symptom of hospitalization making the highest contribution to total DALYs (0.56 per 10⁵ persons; 95% CI: 0.122-1.84). The DALYs decreased to 0.425 (95% CI: 0.137-2.05) per 10⁵ persons per year for those consuming water treated with advanced technology. These values were lower than the acceptable risk (1.97 × 10^-5 DALYs per year). This study revealed the risk of Giardia infection to the people in river networks of Zhejiang Province for the first time, and provides a method to evaluate the risk of Giardia infection. The results are useful for the modification of drinking water quality standards based on cost-benefit analysis.     

甜龙竹不同种植年限对土壤真菌群落的影响

为探究甜龙竹(Dendrocalamus brandisii)种植年限对土壤真菌群落的影响,以不同种植年限(5、 10、 20和40 a)甜龙竹土壤为研究对象,采用高通量测序技术和FUNGuild功能预测相结合的研究方法,分析不同种植年限下甜龙竹土壤真菌群落结构、多样性和功能的差异,揭示驱动土壤真菌群落变化的主要土壤环境因子.结果表明,土壤真菌在门水平上的优势群落为子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、被孢霉门(Mortierellomycota)和毛霉菌门(Mucoromycota);被孢霉门的相对丰度随着种植年限的增加先降低后升高,在不同种植年限差异显著(P<0.05).在纲水平上的优势群落为粪壳菌纲(Sordariomycetes)、伞菌纲(Agaricomycetes)、散囊菌纲(Eurotiomycetes)和被孢霉纲(Mortierellomycetes);粪壳菌纲和座囊菌纲(Dothideomycetes)的相对丰度随着种植年限的增加先降低后升高,在不同种植年限差异显著(P<0.01).土壤真菌Richness指数和Shan...     

不同物质对铬价态测定结果的影响

采用单波长法和双波长法,分别考察了KH2PO4、H3PO4、H2SO4、KNO3、牛肉膏和蛋白胨对Cr(III)和Cr(VI)质量浓度测定的影响。结果显示,Cr(III)和Cr(VI)在测量中是相互影响的,并且Cr(III)对Cr(VI)影响较显著。在单波长法测定中,牛肉膏、蛋白胨及2种酸对Cr(III)和Cr(VI)的影响较钾盐对其影响更为显著,H3PO4和H2SO4对Cr(III)和Cr(VI)的特征吸收峰值影响最大,降低幅度在20%～50%。这些物质对双波长法测定Cr(VI)几乎没有影响;但对Cr(III)测定中,H2SO4和H3PO4的影响较大,其相对误差分别为14.57%和8.87%,其余物质产生的相对误差均小于1.6%。因此,双波长法可用于生物样品中Cr(III)和Cr(VI)的测定,线性范围分别为0～160 mg/L和0～80mg/L。     

湖南品牌战略的现状与对策刍论

湖南省许多企业由于仍然受计划经济体制的阴影笼罩，缺乏竞争观念，品牌意识淡薄，导致品牌难上档次，知名品牌缺少．因此，必须整合湖南品牌战略、实施企业形象战略、培育品牌文化战略和实施品牌战略．     

Delayed dispersal as a potential route to cooperative breeding in ambrosia beetles

Xyleborini are a species-rich tribe of ambrosia beetles, which are haplodiploid and typically mate among siblings within their natal brood chamber. Several characteristics of this tribe would predict the evolution of higher levels of sociality: high genetic relatedness within galleries due to inbreeding, high costs of dispersal and the potential benefit of cooperation in brood care within the natal gallery (e.g. by fungus gardening, gallery extension, offspring feeding and cleaning). However, information on the social system of these beetles is very limited. We examined the potential for cooperative breeding in Xyleborinus saxeseni by monitoring dispersal in relation to brood size and composition. Results show that adult female offspring delay dispersal despite dispersal opportunities, and apparently some females never disperse. The females’ decision to stay seems to depend on the presence of eggs and dependent siblings. We found no indication that female offspring reproduce in their natal gallery, as colonies with many mature daughters do not contain more eggs than those with few or no daughters. There is a significant positive relationship between the number of females present and the number of dependent siblings (but not eggs), which suggests that cooperative brood care of female offspring raises colony productivity by improving survival rates of immatures. Our results suggest that cooperative breeding is likely to occur in X. saxeseni and possibly other xyleborine species. We argue that a closer look at sociality within this tribe may yield important information on the factors determining the evolution of cooperative breeding and advanced social organization.     

菜园土壤的理化性质和微生物生态特征与种植年限的关系

为了研究菜园土壤生态系统的演化，在广州白云区采集共计64个不同种植年限的菜园土壤样本。对土壤丰要物理化学性质和土壤微生物生态特征进行分析，结果表明：土壤粘粒和微网粒含量、土壤全磷、全钾的含量随菜园土的种植年限而增加；呼吸商则随年限升高，土壤细菌／真菌、放线菌／真菌亦有升高的趋势，而微生物碳氮比、土壤微生物商、微生物氮／全氮随年限降低；种植10a左右菜园土壤的Shannon多样性指数和AWCD值最低，40a土壤最高，80a以上土壤的微生物多样性指标有所降低，表明种植80a后的老菜园土壤微生物生态系统有退化的迹象。