集约化柑橘种植抑制土壤磷循环微生物活性

微生物是调节土壤磷循环的关键驱动力.阐明土壤解磷菌的微生物矿化过程对于提高植物养分吸收率和作物产量具有重要意义.通过测定柑橘园与毗邻的自然林地土壤编码碱性磷酸酶基因（phoD）丰度、解磷细菌群落多样性和土壤无机磷组分,探究柑橘种植对土壤微生物获取磷策略的影响机制.结果表明,柑橘种植导致土壤pH下降,土壤有效磷累积,ω（有效磷）平均值高达112 mg·kg^-1,显著高于毗邻的自然林地（3.7 mg·kg^-1）.柑橘种植也会影响土壤磷素组成,柑橘土壤含有较高的可溶态磷（CaCl₂-P）、柠檬酸提取态磷（Citrate-P）和矿物结合态磷（HCl-P）.自然林地土壤各磷组分均显著低于柑橘土壤,而phoD基因丰度和碱性磷酸酶活性显著高于柑橘土壤.高通量测序结果表明,柑橘土壤解磷细菌Shannon指数（4.61）显著低于自然林地（5.35）,群落结构也有别于自然林地.柑橘种植改变了土壤解磷菌的群落组成,自然林地变形菌门的相对丰度显著低于柑橘土壤.土壤有效磷含量与碱性磷酸酶活性呈显著负相关,表明土壤高磷累积抑制土壤解磷细菌的活性.柑橘种植改变了土壤微生物对磷的获取策略,在柑橘园中,土壤微生物主要依赖外源磷,而自然林地土壤微生物主要以微生物分泌碱性磷酸酶矿化有机磷来获取磷的方式满足其生长需求.     

香港石岗——小溪磷、氮浓度的变化及影响因素

研究香港石岗一条小溪在1991年夏雨季溪流中氮和磷的浓度及其在暴雨过程中的变化。结果表明:在基本径流中的氮、磷浓度很低,而在暴雨期间,溪流的氮、磷浓度随水文过程线的上升而增加,但随着暴雨时间的延长,氮、磷浓度随水文过程线增加的趋势会逐渐减弱。与小溪下游汇入的河流比较来看,人为活动对河流的氮、磷浓度影响较大,如不加以控制,将会引起水质恶化。      

Detection of phosphorus species in sediments of artificial landscape lakes in China by fractionation and phosphorus-31 nuclear magnetic resonance spectroscopy

Phosphorus (P) pollution in the sediments of seven artificial landscape lakes was studied via fractionation and phosphorus-31 nuclear magnetic resonance ((31)P NMR) spectroscopy. The lake sediments accumulated significant amounts of P from supplementation with reclaimed water and from runoff from the golf course lawns. The differences in total sediment P among lakes were correlated to the varied pollution extent from the lawns. One striking feature of the artificial lake sediments was the insufficiency of NaOH-extracted Al, which plays an important role in avoiding internal P release during anoxia. Another characteristic was the dominance of orthophosphate in the NaOH-EDTA extractants of the sediments, due to the heavy external P pollution. Phytate, considered prevalent in many soils and lake sediments, as well as polyphosphates and phosphonates which have appeared in some natural lake sediments, was not detected. The rank order of present biogenic P species was monoester-P>DNA-P>pyrophosphate>lipid-P.     

Competitive biodegradation of dichlobenil and atrazine coexisting in soil amended with a char and citrate

The role of char nutrients in the biodegradation of coexisting dichlobenil and atrazine in a soil by their respective bacterial degraders, DDN and ADP, was evaluated. Under growing conditions, their degradation in soil extract was slow with <40% and <20% degraded within 64 h, respectively. The degradation in extracts and slurries of char-amended solids increased with increasing char content, due to nutritional stimulation on microbial activities. By supplementing soil extract with various major nutrients, the measured degradation demonstrated that P was the exclusive limiting nutrient. The reduction in the degradation of coexisting dichlobenil and atrazine resulted apparently from the competitive utilization of P by DDN and ADP. With a shorter lag phase, ADP commenced growing earlier than DDN with the advantage of utilizing P first in insufficient supply. This resulted in an inhibition on the growth of DDN and thus suppression on dichlobenil degradation.     

Country-scale phosphorus balancing as a base for resources conservation

In order to effectively conserve the non-renewable resource phosphorus (P), flows and stocks of P must be known at national, regional and global scales. P is a key non-renewable resource because its use as fertilizer cannot be substituted posing a constraint on the global food production in the long-term. This paper presents a methodology to establish country-wide P balances that emphasises resource use. We develop a material flow analysis (MFA) model that comprises all relevant flows and stocks of P in five subsystems, seven processes and 36 material flows. For quantification, statistical data from economic and agricultural sources as well as available information about P partitioning in natural and anthropogenic processes are used. Special attention is paid to data gaps and uncertainties. The model was tested in two case studies on P management in Turkey and Austria. MFA appears to be a tool well suited for establishing country-wide P balances, provided that national statistics are well-structured and accessible. If a common approach is used for modelling P-flows and stocks, regional and national balances can be compared and linked towards larger scale P balances for an improved management of the resource.     

不同恢复年限刺槐林土壤碳、氮、磷含量及其生态化学计量特征

地处西秦岭山地的甘肃天水吕二沟小流域土壤侵蚀问题严重,上世纪五六十年代开始,当地政府在研究区实施了多年的生态恢复措施以保持水土,但目前尚未有植被恢复对土壤生态计量特征的系统调查.分析不同林龄人工林土壤碳、氮、磷含量及其生态化学计量特征可在一定程度上揭示土壤养分的限制情况.选取黄土丘陵沟壑区不同生长年限(5、20、40、...     

Prioritisation of farm scale remediation efforts for reducing losses of nutrients and faecal indicator organisms to waterways: a case study of New Zealand dairy farming

The international competitiveness of the New Zealand (NZ) dairy industry is built on low cost clover-based systems and a favourable temperate climate that enables cows to graze pastures mostly all year round. Whilst this grazed pasture farming system is very efficient at producing milk, it has also been identified as a significant source of nutrients (N and P) and faecal bacteria which have contributed to water quality degradation in some rivers and lakes. In response to these concerns, a tool-box of mitigation measures that farmers can apply on farm to reduce environmental emissions has been developed. Here we report the potential reduction in nutrient losses and costs to farm businesses arising from the implementation of individual best management practices (BMPs) within this tool-box. Modelling analysis was carried out for a range of BMPs targeting pollutant source reduction on case-study dairy farms, located in four contrasting catchments. Due to the contrasting physical resources and management systems present in the four dairy catchments evaluated, the effectiveness and costs of BMPs varied. Farm managements that optimised soil Olsen P levels or used nitrification inhibitors were observed to result in win-win outcomes whereby nutrient losses were consistently reduced and farm profitability was increased in three of the four case study farming systems. Other BMPs generally reduced nutrient and faecal bacteria losses but at a small cost to the farm business. Our analysis indicates that there are a range of technological measures that can deliver substantial reductions in nutrient losses to waterways from dairy farms, whilst not increasing or even reducing other environmental impacts (e.g. greenhouse gas emissions and energy use). Their implementation will first require clearly defined environmental goals for the catchment/water body that is to be protected. Secondly, given that the major sources of water pollutants often differed between catchments, it is important that BMPs are matched to the physical resources and management systems of the existing farm businesses.     

氮磷对微囊藻和栅藻生长及竞争的影响

为了揭示不同营养条件下,藻类优势种的形成规律,选取了3种具有代表性水体的营养盐浓度,对于蓝藻水华的常见种铜绿微囊藻和绿藻水华的常见种四尾栅藻进行了竞争实验.通过竞争抑制参数对相互间的竞争关系进行了分析.结果表明,在贫营养水平下,栅藻的存在能够刺激微囊藻的生长,N/P值越小,刺激作用越明显,微囊藻也能刺激栅藻的生长;富营养水平下,竞争抑制作用与N/P有关;超富营养水平下,栅藻对微囊藻的抑制能力约为微囊藻对栅藻的抑制能力的3倍,N/P值的变化对竞争抑制作用的影响不明显.在较低氮磷浓度的水体中,微囊藻容易成为优势种,而在较高的氮磷浓度的水体中,四尾栅藻更容易成为优势种.     

蜂窝煤灰渣和磷肥结合修复铅污染贫磷潮土的研究（Remediation of Lead Polluted Chaotu Soil with Low Phosphorus Availability by Application of Honeycomb Briquette Combustion Residue and Phosphorus Fertilizer）

利用蜂窝煤灰渣和磷肥结合稳定铅污染贫磷(Olsen-P=2.50mg·kg-1)潮土中铅的可行性.采用盆栽试验,设置0和500mg·kg-1两个Pb用量,灰渣用量分别为干土质量的0%和2%,P:Pb分别为0和4.种植黑麦草,植物生长85d后收获,测定植物产量、土壤DTPA-Pb、Olsen-P含量、pH值和电导率(EC).结果表明,在两个Pb用量及两个P:Pb比例下,加入灰渣后,土壤的DTPA-Pb含量均降低,平均降低5.61%.其中加铅未加磷处理灰渣效果达到0.05的显著水平,各加Pb处理中,同时加入磷肥和灰渣处理土壤的DTPA-Pb含量最低;加入灰渣后处理土壤中的Olsen-P含量均增加,平均增加了2.71mg·kg-1,各处理土壤pH值上升约0.1个单位,加入灰渣也导致各处理土壤的EC增加.各处理条件下加入灰渣后植物产量均减小.在未加磷土壤中加入Pb后,土壤Olsen-P含量显著增加(p<0.05),表明高铅有效性下,植物可能通过根系分泌物增加了土壤磷的有效性.以上结果表明,蜂窝煤灰渣有可能用于降低污染土壤中铅的有效性,但其对植物生长的抑制作用需要克服.     

植物细胞色素P450酶系的研究进展及其与外来物质的关系

植物细胞色素P45 0是分子量为 40— 60KD、结构类似的一类血红素 硫铁蛋白。它以可溶性和膜结合两种形态存在于植物细胞内 ,可催化多种化学反应 ,在防御植物免受有害物质侵害方面具有重要作用。目前已克隆 90多个植物细胞色素P45 0基因。本文概述了植物P45 0基因表达调控与环境、发育、组织特异性关系的研究进展。认为植物P45 0同工酶在环境毒物生物修复和在抗外源毒素的转基因植物方面具有很高的应用前景