Adsorption, transport and degradation of fipronil termiticide in three Hawaii soils

BACKGROUND: The behavior of the termiticide fipronil in soils was studied to assess its potential to contaminate ground and surface water. This study characterizes (1) adsorption of fipronil in three different soils, (2) transport of fipronil through leaching and runoff under simulated rainfall in these soils and (3) degradation of fipronil to fipronil sulfide and fipronil sulfone in these soils. RESULTS: The adsorption experiments showed a Freundlich isotherm for fipronil with K_oc equal to 1184 L kg^?1. In the leaching experiments, the concentration of fipronil and its metabolites in leachate and runoff decreased asymptotically with time. The concentration of fipronil in the leachate from the three soils correlated inversely with soil organic carbon content. The degradation experiment showed that the half‐life of fipronil in the soils ranged from 28 to 34 days when soil moisture content was 75% of field capacities, and that 10.7–23.5% of the degraded fipronil was transformed into the two metabolites (fipronil sulfide and fipronil sulfone). CONCLUSION: Fipronil showed large losses through leaching but small losses via runoff owing to low volumes of runoff water generated and/or negligible particle‐facilitated transport of fipronil. The half‐life values of fipronil in all three soils were similar. Copyright © 2011 Society of Chemical Industry     

外源生物质炭对土壤中铵态氮素滞留效应的影响

以生物质炭和黄棕壤为研究材料,通过阳离子交换量测定、铵态氮等温吸附实验以及模拟土柱淋溶,研究生物质炭对土壤铵态氮素滞留效应的影响。发现生物质炭以1%、3%和5%添加后,土壤CEC值分别增加9.4%、14.7%和19.7%,铵态氮素淋失量分别减少22%、39%和47%,氮素滞留量分别增加15%、5%和14%;同时影响氮素在土层中的分布,其中加生物质炭土壤的氮素集中在土柱上部5～7cm处,而不加生物质炭土壤集中在中部偏下9～11cm处。结果表明,生物质炭能够提高土壤对铵态氮素的吸附能力,显著降低土壤铵态氮素养分的淋失。     

有机无机肥料配合施用对设施番茄产量、品质及土壤硝态氮淋失的影响

利用田间小区试验,研究了有机无机肥配合施用模式对番茄产量、品质及氮素在土壤中累积和淋失的影响.结果表明:(1)与肥料用量较高的习惯施肥处理相比,大幅减少肥料施用的不同有机无机肥配合施用模式均能保证番茄产量稳定,显著提高经济效益,平均增收19 127元·hm-2,其中(3/4)化肥N+(1/4)猪粪N模式处理经济效益最高.(2)施用有机肥的3个有机无机肥配合施用模式处理可降低番茄果实中的硝酸盐含量,较全部施用化肥处理和习惯施肥处理的分别降低5.4％和7.0％;施用有机肥的3个有机无机肥料配合施用模式处理可提高番茄果实中Vc的含量,较全部施用化肥处理的提高9.4％.(3)与番茄种植前相比,番茄收获后土壤硝态氮含量总体上表现出表层增加、深层降低的趋势;大幅减施肥料的有机无机肥配合施用模式处理各土层硝态氮含量均低于习惯施肥处理相应土层硝态氮含量.(4)有机无机肥配合施用模式可显著降低渗漏水中硝态氮渗漏量,较全部施用化肥处理和习惯施肥处理的平均分别降低35.5％和55.1％.在试验条件下,综合考虑产量、经济效益和环境效益的适宜有机无机肥料配合施用模式为(3/4)化肥N+(1/4)猪粪N模式处理.     

包钢尾矿重金属溶解浸出实验研究

本文研究了包钢尾矿中重金属(pb、Cd、Zn)在不同条件下的溶解浸出特性,研究表明混合搅拌3h可使体系达到溶解平衡;浸出液的重金属离子浓度随液固比(L/S)的减少而逐渐增加;重金属的溶解浸出率随浸取液pH值的降低而增加,pH在2-6时浸出率变化不大,当pH为1时,尾矿中重金属的浸出率显著增加;浸取剂中H+对各元素浸出的影响程度分别为Pb＞Cd＞＞Zn;浸出率也随浸取温度的升高而增大.     

附子总生物碱的提取工艺研究

[目的]研究附子总生物碱的提取工艺,优选最佳提取条件。[方法]以提取率、总生物碱收率和总生物碱纯度为指标,采用单因素试验法,考察提取溶剂、提取方法、提取温度、粉碎度、料液比、提取时间和提取次数对附子中总生物碱提取率的影响,并优选出最佳提取工艺条件。[结果]最佳提取工艺条件为:在15℃条件下,将附子粉按1∶10(g/ml)加入无水乙醇,冷浸3次,每次1 d;在此条件下,浸膏得率、总生物碱收率和总生物碱纯度分别为3.15%、0.64%和20.32%。[结论]该方法高效、低毒、经济、操作方便、工艺可控,较适合附子总生物碱的提取和工业化生产。     

Soil respiration and nitrogen leaching decreased in grey alder (Alnus incana (L.) Moench) coppice after clear-cut

ABSTRACT

Grey alder (Alnus incana) is a highly productive indigenous tree species, potential for short-rotation forestry in the Baltic and Nordic countries. The aim of the study was to investigate the development of a new forest generation, as well as the nitrogen (N) and carbon (C) storages and fluxes in a grey alder regenerating coppice (COP) after clear-cut and in an adjacent unharvested 21-year-old stand (MAT), which had reached its bulk maturity. The regeneration of COP was rapid and 5 years after clear-cut, stem mass was 6.4?t?ha^?1. The nitrogen demand of the aboveground part of the 5-year-old COP trees was estimated to be roughly half of the corresponding value for MAT, depending mostly on leaf production. The annual N leaching flux in MAT was in the range of 16–29?kg?ha^?1, the corresponding values for COP were roughly half of that. Net nitrogen mineralization did not differ significantly between MAT (117?kg?ha^?1) and COP (129?kg?ha^?1). For the soil respiration study, a 32-year-old grey alder stand growing at a similar site was included; soil respiration was significantly higher in MAT compared to COP in all study years in both studied stands.     

浙北平原不同种植年限蔬菜地土壤氮磷的积累及环境风险评价

长期过量施肥可导致蔬菜地土壤养分大量累积、养分利用效率下降和环境污染风险增加。以浙北平原不同种植年限蔬菜地土壤为研究对象,采用化学测试方法研究了菜地土壤氮和磷的积累及其淋失潜力的变化。结果表明,随着种植年限的增加,蔬菜地土壤全磷、有效磷（Olsen P）和NO3-N呈明显的积累;蔬菜种植年限为〈2、2～5、6～10、11～20、20～30和＆gt;30a的表土全P平均分别为0.66、0.75、1.07、1.49、2.40和2.12g·kg-1,有效P平均分别为13.2、37.8、42.2、70.2、137.9和101.7mg·kg-1,NO3-N平均分别为9.15、13.58、50.18、46.48、73.28和74.20mg·kg-1,同时土壤N和P垂直下移渐趋明显。土壤水溶性磷含量随土壤有效磷（OlsenP）积累的变化存在一个明显的突变点,相对应的土壤OlsenP临界值约为60mg·kg-1。随着种植年限增长,蔬菜地地表径流中氮和磷浓度呈明显增加,利用年限为20～30a的蔬菜地径流中可溶性P和NO3-N浓度分别约为利用年限〈2a蔬菜地的13.12和9.48倍。研究认为,长期超量施肥已导致这一地区蔬菜地土壤养分的过度积累,在蔬菜生产中应重视和提倡平衡施肥,控制土壤氮磷的积累。     

~（95）Zr在土壤中的淋溶和迁移分布

采用模拟土柱法研究了95Zr在2种淹水土壤（小粉土、红黄壤）中的淋溶和垂直迁移。结果表明：（1）淋溶后收集到的全部淋溶液中95Zr的含量较少,小粉土淋溶液中95Zr为总活度的3.05%,黄红壤淋溶液中95Zr为总活度的3.00%;（2）滞留于土壤中的95Zr绝大部分分布在土壤表层0～1.0cm范围内,小粉土中有67.80%～80.18%的95Zr滞留于0～1.0cm土层范围内,黄红壤中有74.05%～86.95%的95Zr滞留于0～1.0cm土层范围内;（3）土壤中95Zr比活度与距土壤表层深度分布呈单项指数规律。     

重庆酸雨区缙云山典型林分冠层酸雨淋洗特征

选取重庆缙云山的针阔混交林、常绿阔叶林、毛竹林、灌木林4种典型林分,观测酸性降水过程中林外雨、穿透雨及干流等林内水分转换分量中的主要离子含量变化,分析林分冠层对雨水化学组成的影响,结果表明:(1)降雨中的离子当量浓度大小依次是SO42-＞Ca2+＞ NH4+＞Mg2+＞K+＞Na+＞NO3-;(2)降雨经过林冠层后pH值降低,干流的酸化程度增加最大;(3)降雨经林冠层后离子浓度明显增加(除灌木林),穿透雨中通量增加最大的阴离子和阳离子分别为SO42-(2.19×103～6.47×103 eq·hm-2)和Ca2+(1.41×103～3.39×103 eq-hm-2),离子来源主要为大气沉降和植物分泌物或淋出;(4)同一离子在不同林分的干流和穿透雨中的通量变化不同,反映出不同林分冠层的离子交换性差异.在针阔混交林中,林下降雨净淋溶量大小顺序为SO42-＞Ca2+＞ NO3-＞K+＞NH4+＞Mg2+＞ Na+;常绿阔叶林为SO42-＞ Ca2+＞ K+＞NO3-＞ NH4+＞ Mg2+ ＞Na+;毛竹林为Ca2+＞ SO42-＞ K+＞NO3-＞ NH4+＞Na+＞Mg2+;灌木林为Ca2+＞ NO3-＞ K+＞ Na+＞Mg2+＞ NH4+＞ SO42-.     

A COMPARISON OF TOOLS FOR PRUNING PINUS PINASTER

Dielectric heating by radio-frequency power has been established in various countries as a practical means for the rapid gluing of wood with thermosetting adhesives. The high-frequency drying of wood and wooden products as an economical substitute for conventional drying methods is being investigated extensively.

Especially in South Africa, it seems the appropriate time to consider this process again. This article is the first in a series and reviews the general principles. Further papers will present values of dielectric properties of South African pines and deal with the possibilities of drying wood by this process.