LC-MS/MS法研究甲磺隆和氯磺隆在不同条件土壤中的残留行为

在建立液相色谱三重串联四极杆质谱（LC-MS/MS）检测技术的基础上,采用PVC材料的圆柱形盆钵栽培方法,研究了不同土壤环境条件下甲磺隆和氯磺隆的残留特性。结果表明,甲磺隆和氯磺隆在水稻根际和非根际土壤中的残留量均呈不断下降趋势。处理后15d,根际和非根际土壤中两种农药残留量分别下降了44.7%和41.5%（甲磺隆）及38.7%和40.1%（氯磺隆）,根际和非根际的残留差异不显著（P〉0.05）;处理后31d,残留量分别下降了77.7%和64.8%（甲磺隆）及62.7%和50.1%（氯磺隆）,差异达极显著水平（P〈0.01）;处理后63d,残留量分别下降了96.4%和85.1%（甲磺隆）及90.0%和79.4%（氯磺隆）,残留差异达极显著水平（P〈0.01）。甲磺隆的降解趋势和氯磺隆基本一致,但下降幅度比氯磺隆大。二者在水稻根际和非根际土壤中的残留量均符合一级动力学方程式C=C0e-λ（tC代表浓度;C0代表初始浓度;t时间）,决定系数范围在0.9342～0.9957之间。在种植水稻的条件下,下层土的农药残留量呈先上升后下降的趋势,处理后数日内达最高点,之后不断下降,122d后低于检测限。水稻下层土残留的从无到有说明农药在土壤中的淋溶可能是水田环境农药残留降解的原因之一。干旱土壤条件下,土壤的淋溶作用不明显。说明水旱轮作有利于农药残留在土壤环境中的降解。     

~(14)C-绿磺隆在土壤中的可提态残留、结合残留和矿化研究

本文对14 C 绿磺隆在 7种不同类型土壤中形成结合残留 ( 14 C ER)、可提态残留( 14 C ER)以及矿化为14 C CO2 的规律、影响14 C BR的主要因子及其在腐殖质中的分布规律等进行了研究。结果表明 :( 1 ) 14 C 绿磺隆在土壤中形成的14 C ER含量与土壤pH呈显著正相关 ,与土壤粘粒和有机质含量呈显著负相关 ,14 C ER中的绿磺隆母体化合物的消减满足一级反应动力学方程 ,其在 7种土壤中的半减期分别为 1 3 0～ 1 3 3 3d。pH是影响绿磺隆母体化合物降解的主要因子 ;( 2 ) 14 C 绿磺隆在 7种土壤中的14 C BR含量与土壤pH呈显著负相关 ,并与土壤粘粒含量呈显著正相关 ,土壤pH是14 C 绿磺隆在土壤中形成BR的主要影响因子 ;( 3 ) 14 C 绿磺隆形成的14 C BR主要分布在富啡酸和胡敏素中 ;14 C BR分布在胡敏酸中的相对百分比约为 2 % ,在14 C 绿磺隆BR的形成过程中 ,富啡酸的作用 >胡敏素 胡敏酸 ;( 4) 14 C 绿磺隆在 7种土壤中的14 C BR含量 ,在培养 2 0d内均随时间而快速增加 ,2 0d后变化量较小。 7种土壤中的14 C BR含量最大值分别占引入量的 53 5%、40 9%、3 7 8%、1 6 4%、42 5%、41 0 %和 3 1 3 % ;( 5)培养 90d内 ,14 C 绿磺隆通过三嗪杂环开环矿化为14 CO2 的量约占引入量的 4%～9% ,而土壤 1表明14 C     

土壤中~(14)C-甲磺隆的结合残留及其在腐殖质中的分布规律

实验室培养条件下 ,研究了14 C 甲磺隆在 7种不同类型土壤中形成结合残留( 14 C BR)的规律、主要影响因子及14 C BR在腐殖质中的动态分布规律等。结果表明 :( 1 ) 14 C 甲磺隆在 7种土壤中形成的14 C BR含量在培养初期的 2 0d内与土壤pH呈显著负相关且与土壤粘粒含量呈显著正相关 ;而 2 0d后 ,14 C BR含量只与土壤pH呈显著负相关。土壤pH是14 C 甲磺隆在土壤中形成BR的主要影响因子。14 C -甲磺隆在各类土壤中的14 C BR的最大值分别占引入量的 48 5%、46 5%、52 6%、1 9 3 %、49 7%、42 0 %和 46 5% ;( 2 )在整个培养试验过程中 ,14 C 甲磺隆在 7种不同类型土壤中的14 C BR ,主要分布在富啡酸和胡敏素中 ,前者中的相对百分比大于后者 ,而在胡敏酸中的相对百分比较小。土壤中14 C 甲磺隆BR的形成过程中 ,富啡酸的作用 >胡敏素 胡敏酸     

降解菌S113对甲磺隆污染土壤生物修复作用的研究

在室内条件下,研究了降解菌S113(Methylopila sp.)对甲磺隆污染土壤的修复作用。S113能够以甲磺隆为唯一碳源生长,72h对50mgL-1甲磺隆的降解率达98.38%。投加降解菌S113可显著提高土壤中甲磺隆的降解速率。当甲磺隆浓度为10mgkg-1干土,S113接种量为108个g-1土时,第30天土壤中甲磺隆降解率为76.9%,对照土壤中甲磺隆降解率仅为11.9%。S113降解甲磺隆的速率和接种量呈正相关,当接种量减少为105个g-1干土时,降解菌对甲磺隆的降解作用微弱。在土壤中甲磺隆浓度较低的条件下,S113的降解效果显著,而当土壤中甲磺隆浓度达到50mgkg-1时,甲磺隆降解率仅为39.6%。S113降解土壤中甲磺隆的最适温度为30℃,第30天的降解率可达75.9%。当温度为25℃、20℃时,第30天甲磺隆降解率仅为53.5%和23.9%。S113菌剂灌根,能不同程度地缓解土壤中浓度为40、80μgkg-1的甲磺隆对玉米生长的抑制作用,但当甲磺隆浓度增加到120μgkg-1时,接种S113对药害解除作用不显著。结果表明,人工接种降解菌S113,能有效去除土壤中甲磺隆残留。     

土壤中结合残留态甲磺隆的微生物降解研究

主要进行了优选菌株青霉 (Penicilliumsp .)对土壤中结合残留态甲磺隆的降解研究 ,结果表明 ,优选菌株的引入对土壤中可提态甲磺隆的影响不大 ,但对结合残留态甲磺隆的降解和矿化有较大影响。在结合残留态甲磺隆中 ,优选菌株青霉的引入有利于松结态甲磺隆尤其是松结态富里酸甲磺隆的降解。     

水稻土中广灭灵残留动态及降解影响因子的研究

对水稻土中广灭灵残留消解动态及降解影响因子研究结果表明 ,广灭灵在 4种水稻土中降解符合 1级动力学方程C =C0 e-kt,其降解半衰期为 5 7～ 2 2 0d。广灭灵降解以微生物降解为主 ,土壤灭菌处理大大降低广灭灵降解速率 ,土壤理化性质、温度、湿度、pH值是影响广灭灵降解的重要因素。广灭灵降解速率与不同类型水稻土有机质含量呈显著负相关关系 ,相关系数为 - 0 8336。随温度上升而广灭灵降解有加速趋势 ,但常温 2 5℃时广灭灵降解速率高于 35℃处理 ,增加土壤湿度及施用石灰增加土壤 pH值均加快广灭灵降解速率     

甲磺隆降解菌FLDA的分离鉴定及其降解特性研究

从生产甲磺隆的农药厂内采取污泥，经驯化富集后筛选到一株能高效降解甲磺隆的细菌FLDA，根据表型特征、生理生化特性及16S rDNA序列同源性分析，将FLDA初步鉴定为假单胞菌（Pseudomonas sp）。该菌能在含甲磺隆（30mgL^-1）的基础盐液体培养基中降解甲磺隆，5d降解率达72．6％，该菌降解甲磺隆的最适pH为7．0，最适温度为30℃，该菌降解甲磺隆的速率和起始接种量呈正相关。酶的定域实验表明，该菌中甲磺隆水解酶为胞内酶。FLDA投加土壤，可提高土壤中甲磺隆的降解速率。     

碘甲磺隆钠盐在水溶液中的光解研究

为了解碘甲磺隆钠盐在水溶液中的光降解特性,评价其环境安全性,以太阳光和高压汞灯为光源,进行光解试验,研究了碘甲磺隆钠盐在不同水溶液中的光解行为及水体pH值对其光解的影响。结果表明,碘甲磺隆钠盐在所有试验水体中的降解均符合一级动力学方程,不同水体中碘甲磺隆钠盐的半衰期分别为14.29～21.26h（太阳光）与2.29～3.76min（高压汞灯）,两种光源下碘甲磺隆钠盐在各自然水体中的降解速率依次为井水〉河水〉池塘水〉稻田水。不同pH值水体中的光解实验表明,碘甲磺隆钠盐在酸性介质中的光解比在碱性介质中快,顺序为pH5〉pH7〉pH9〉pH11。     

甲磺隆胁迫下小麦根际土壤微生物的菌群结构响应

采用根箱盆栽法,研究了甲磺隆对我国南方小麦根际与非根际土壤中三大类群微生物菌群结构的影响。结果表明:在2μg/g甲磺隆浓度胁迫下,普通细菌受到显著抑制(P<0.01),耐受细菌在前30天受影响显著,但随着甲磺隆的降解和根际效应的加强而逐渐减弱;真菌是甲磺隆污染土壤中的活跃菌群,处理根际与非根际土壤中耐受真菌与对照相比30天后即达到P<0.01的显著水平;放线菌是甲磺隆胁迫下的劣势菌。微生物三大类群对甲磺隆胁迫的响应依次为放线菌>细菌>真菌,真菌的此类特性为寻求甲磺隆高效降解菌及其快速降解机制提供了可能。     

黑土中乙草胺残留和微生物变化的时间特征研究

通过黑土室外盆栽试验,研究了种植玉米和未种植条件下乙草胺在玉米生长苗期的残留变化规律及土壤微生物量碳的动态特征。研究表明:乙草胺在土壤中半衰期较短,土壤微生物活性是影响其降解的主要因素。但是,由于施用化肥极大地刺激了微生物活性,因而,乙草胺施用对土壤微生物量碳影响并不显著。然而,玉米的种植对土壤微生物量和土壤乙草胺残留数量有着显著的影响。种植玉米条件下土壤微生物量碳显著增加,同时,土壤中乙草胺残留量降低,说明种植玉米有助于微生物活性的提高和乙草胺生物毒害性的降低。     

添加黏土及植物残体混合物对沙质土壤中呼吸作用和微生物量碳、氮有效性的影响

Crop yields in sandy soils can be increased by addition of clay-rich soil, but little is known about the effect of clay addition on nutrient availability after addition of plant residues with different C/N ratios. A loamy sandy soil(7% clay) was amended with a clay-rich subsoil(73% clay) at low to high rates to achieve soil mixtures of 12%, 22%, and 30% clay, as compared to a control(sandy soil alone) with no clay addition. The sandy-clay soil mixtures were amended with finely ground plant residues at 10 g kg~(-1): mature wheat(Triticum aestivum L.) straw with a C/N ratio of 68, mature faba bean(Vicia faba L.) straw with a C/N ratio of 39, or their mixtures with different proportions(0%–100%, weight percentage) of each straw. Soil respiration was measured over days 0–45 and microbial biomass C(MBC), available N, and p H on days 0, 15, 30, and 45. Cumulative respiration was not clearly related to the C/N ratio of the residues or their mixtures, but C use efficiency(cumulative respiration per unit of MBC on day 15) was greater with faba bean than with wheat and the differences among the residue mixtures were smaller at the highest clay addition rate. The MBC concentration was lowest in sole wheat and higher in residue mixtures with 50% of wheat and faba bean in the mixture or more faba bean. Soil N availability and soil p H were lower for the soil mixtures of 22% and 30% clay compared to the sandy soil alone. It could be concluded that soil cumulative respiration and MBC concentration were mainly influenced by residue addition, whereas available N and p H were influenced by clay addition to the sandy soil studied.     

秸秆碳的田间原位分解和微生物量碳的周转特征

应用14 C示踪技术研究了杂交狼尾草秸秆在稻麦轮作田中为期 1年的原位分解。结果表明 :秸秆用量对其分解率影响甚微 ,1年后秸秆C分解了 72 %左右 ,分解速率常数为 2 7× 1 0 - 3d- 1,但秸秆用量的多少与土壤原有碳的分解和土壤有机碳平衡密切相关。黄棕壤原有C年分解率为 5 4 5 %～ 6 0 7% ,分解速率常数在 1 0 4× 1 0 - 4～ 1 1 8× 1 0 - 4d- 1之间。随秸秆用量增加 ,黄棕壤原有C分解率和分解量均增加 ,土壤有机碳的亏缺减少。微生物量14 C占加入秸秆14 C的 3 79%～ 1 0 63% ,占土壤残留14 C的 1 2 2 7%～1 7 4 3% ,其大小变化及减少程度均较微生物量12 C显著。微生物量12 C约为微生物量14 C的 0 74～ 3 85倍 ,说明大多数情况下 ,土壤原有C仍是土壤微生物活动所需能量和养分的主要来源。微生物量14 C的周转率在 1 1 0～ 1 1 8a- 1之间 ,微生物量12 C的周转率在 0 97～ 1 0 6a- 1之间。增加秸秆用量可加快土壤微生物量C的周转速度 ,反过来微生物量C周转速度的加快又加速了秸秆C和土壤原有C的分解。土壤原有C和秸秆C的分解进程与微生物量12 C和微生物量14 C的动态变化趋势一致 ,说明有机碳分解的快慢是土壤微生物活动强弱的外在表现。     

Soil C balance in a long-term field experiment in relation to the size of the microbial biomass

Soil C balances were calculated in a field experiment started in 1956. Treatments include a fallow and soils receiving different N fertilizers or organic amendments. By assuming the absence of a priming effect, the degree of mineralization of crop residues and organic amendments was calculated. Crop residue mineralization was not affected by a more than 50% decrease in the size of the microbial biomass in soil fertilized with (NH₄)₂SO₄, which had caused the pH of this soil to drop from 6.6 to 4.4. More C had accumulated per unit C input in peat-and sewage sludge-amended soils than in any of the other soils, suggesting that peat and sewage sludge were more resistant to microbial attack. Recalcitrance of substrate C was an adequate explanation for the low ratio of biomass C to soil C in the peat-amended soils, but not in the sewage sludge-amended soil. There was a close linear relationship (r=0.94) between the content of microbial biomass C in the soil measured in 1990 and cumulative C losses from the soil since 1956. Compared to the relationship between soil biomass C and soil organic C concentrations, the linear relationship between microbial C and cumulative C losses suggested that the significantly reduced biomass in the sewage sludge-amended soil was at least partially due to the presence of toxic substances (presumably elevated heavy metal concentrations) in this soil and was probably not affected by the somewhat low pH (5.3) in this soil.     

好氧土壤中[C环-U-14C] 丙酯草醚的结合残留及其在腐殖质中的分布动态

农药的环境行为与归趋,尤其是结合残留研究,是新农药安全性评价的重要内容之一,这关系到新农药的科学使用。本文利用14C同位素示踪技术,研究了[C环-U-14C]丙酯草醚(ZJ0273)在3种不同类型好氧土壤中的结合残留及其在富啡酸、胡敏酸和胡敏素中的动态分布。结果表明：（1）在整个培养过程中,土壤中的丙酯草醚结合残留量均随时间而递增。培养至75d,红砂土（S1）、黄松土（S2）与淡涂泥田（S3）中的14C-BR最大值分别为引入量的12.55%,20.35%和20.49%,且富含有机质和pH较高的土壤更易与丙酯草醚形成结合残留;（2）丙酯草醚与富啡酸、胡敏酸和胡敏素形成的结合残留,含量大小依次为富啡酸＞胡敏素＞胡敏酸。因此,丙酯草醚与土壤基质形成结合残留的过程中,富啡酸起主要作用,而胡敏酸的作用最小。     

Abundance, production and stabilization of microbial biomass under conventional and reduced tillage

Soil tillage practices affect the soil microbial community in various ways, with possible consequences for nitrogen (N) losses, plant growth and soil organic carbon (C) sequestration. As microbes affect soil organic matter (SOM) dynamics largely through their activity, their impact may not be deduced from biomass measurements alone. Moreover, residual microbial tissue is thought to facilitate SOM stabilization, and to provide a long term integrated measure of effects on the microorganisms. In this study, we therefore compared the effect of reduced (RT) and conventional tillage (CT) on the biomass, growth rate and residues of the major microbial decomposer groups fungi and bacteria. Soil samples were collected at two depths (0-5 cm and 5-20 cm) from plots in an Irish winter wheat field that were exposed to either conventional or shallow non-inversion tillage for 7 growing seasons. Total soil fungal and bacterial biomasses were estimated using epifluorescence microscopy. To separate between biomass of saprophytic fungi and arbuscular mycorrhizae, samples were analyzed for ergosterol and phospholipid fatty acid (PLFA) biomarkers. Growth rates of saprophytic fungi were determined by [¹⁴C]acetate-in-ergosterol incorporation, whereas bacterial growth rates were determined by the incorporation of ³H-leucine in bacterial proteins. Finally, soil contents of fungal and bacterial residues were estimated by quantifying microbial derived amino sugars. Reduced tillage increased the total biomass of both bacteria and fungi in the 0-5 cm soil layer to a similar extent. Both ergosterol and PLFA analyses indicated that RT increased biomass of saprophytic fungi in the 0-5 cm soil layer. In contrast, RT increased the biomass of arbuscular mycorrhizae as well as its contribution to the total fungal biomass across the whole plough layer. Growth rates of both saprotrophic fungi and bacteria on the other hand were not affected by soil tillage, possibly indicating a decreased turnover rate of soil microbial biomass under RT. Moreover, RT did not affect the proportion of microbial residues that were derived from fungi. In summary, our results suggest that RT can promote soil C storage without increasing the role of saprophytic fungi in SOM dynamics relative to that of bacteria.     

Microbial biomass formed from 14C, 15N-labelled plant material decomposing in soils in the field

The decomposition of ¹⁴C, ¹⁴N-labelled medic (Medicago littoralis) material and the net formation and decay of isotope-labelled biomass have been measured in four South Australian soils in the field over 4 yr. The field sites were in similar climatic zones but two sites received about twice as much rainfall as the others. The soils were calcareous and of similar pH, but differed in texture and organic matter content. The decomposition of the organic-¹⁴C and organic-¹⁵N residues were, for a given site, similar. Initially, the concentrations of labelled residues decreased rapidly, then very slowly. Decomposition rates in a heavy clay soil were significantly less than in the other soils during the first 16 weeks after incorporation of plant material, but thereafter, rates of decomposition in all soils were similar, despite differences in soil texture and climate. More than 50% of the medic-¹⁴C had disappeared from all soils after 4 weeks of decomposition and only 15–20% of the medic-¹⁴C remained as organic residues after 4 yr. Of the medic-¹⁵N 60–65% remained as organic residues after 32 weeks decomposition; the percentage decreased to 45–50% after 4 yr.The amounts of ¹⁴C, ¹⁴N-labelled biomass, formed from decomposing plant material, were maximal 4–8 weeks after incorporation of plant material into the soils. In samples taken at 8 weeks from the sandy Roseworthy soil, biomass-¹⁴C and -¹⁵N accounted for 14 and 22% respectively of the total organic-¹⁴C and -¹⁵N residues present. Thereafter in this soil, the concentrations of biomass-¹⁴C and -¹⁵N decreased, rapidly at first then more slowly. Nevertheless, throughout most of the decomposition the rates of decrease in the concentrations of biomass-¹⁴C and -¹⁵N exceeded those of the non-biomass, labelled organic residues.The proportions of ¹⁴C, ¹⁵N-labelled materials accounted for in the labelled biomass varied between soils. Soils of higher clay content generally retained higher proportions of residual organic-¹⁴C and -¹⁴N in the biomass, even though the net rates of decomposition of total labelled residues did not differ significantly between soils during most of the decomposition.     

有机物料对强酸性茶园土壤的酸度调控研究

通过室内培养的方式,研究了不同添加剂量下,不同C/N与灰化碱含量的有机物料对酸性茶园土壤的改良能力.试验结果表明:有机物料的添加可以有效地减少土壤交换性酸、铝饱和度,增加土壤交换性碱基,但是在调节土壤pH能力上并非一定有效.初始阶段,“灰化碱”的释放与有机氮的矿化提高了土壤的pH,随后pH由于硝化作用出现不同程度的下降.C/N高的作物秸秆(小麦和水稻秸秆)能够有效地抑制硝化,使pH下降幅度较小;而C/N低的作物秸秆(花生秸秆和菜籽饼)促进硝化,使pH大幅度下降.最终土壤pH与其C/N呈正相关性(y=0.00343x+4.14,r=0.977),而与其灰化碱含量无关.并且随着秸秆添加剂量的加大,C/N高的作物秸秆最终调剂pH的能力是显著提高的(P＜0.05),而C/N低的作物秸秆最终调剂pH的能力没有显著提高(P＜0.05).因此,C/N高的作物秸秆可能更适合土壤酸度的长期调节,与其相关的田间试验需要进一步进行证实.