微生物和生物炭联用对猪粪堆肥后重金属Pb和Cd的钝化效果

为探讨微生物和生物炭联用对畜禽粪便堆肥过程中重金属钝化效果的影响,该文研究生物炭(花生壳炭、木屑炭、玉米秸秆炭)与复合微生物菌剂联用对重金属Pb、Cd形态转化及钝化效果的影响。试验结果表明:9个处理高温期维持天数均达无害化卫生要求,生物炭添加比例对堆肥过程中温度变化影响显著。对Pb的钝化效果最优处理是24%花生壳生物炭和1%的菌剂(T9),可交换态分配率较堆前下降16.32%,钝化效率为74.60%。对Cd的钝化效果最优的处理是24%木屑炭和1.5%的菌剂(T3),交换态Cd与堆前相比下降7.96%,钝化效率为58.13%。统计分析结果表明,重金属Pb、Cd的钝化效果与堆肥过程中平均pH值呈显著正相关,重金属Pb的钝化效果与堆肥过程中温度平均值呈显著正相关,重金属Cd的钝化效果与有机质降解率呈显著正相关。     

Biotic and abiotic processes of nitrogen immobilization in the soil-residue interface

The interface between decaying plant residues and soil is a hotspot for microbial immobilization of soil inorganic N. Recent studies on forest and grassland soils have demonstrated that rapid abiotic immobilization of inorganic N is also induced by the presence of plant residues. We, therefore, examined (1) how N immobilization varies with distance from the soil-residue interface and (2) whether abiotic immobilization occurs in agricultural soils. Spatiotemporal changes of N immobilization in the soil-residue interface were evaluated using a box that enabled soil to be sampled in 2 mm increments from a 4 mm-thick residue compartment (RC). The RC was filled with paddy soil containing ground plant residue (rice bran, rice straw or beech leaves) uniformly at a rate of 50 g dry matter kg⁻¹. Soil in the surrounding compartments contained no residue. After aerobic incubation for 5, 15 and 30 days at 25 °C, soils in each compartment were analyzed. After 5 days, significant depletion of inorganic N occurred throughout a volume of soil extending at least 10 mm from the RC in all residue treatments, suggesting extensive diffusion of inorganic N towards the RC. The depletion within 10 mm of the RC amounted to 5.0, 4.3 and 3.4 mg for rice bran, rice straw and beech leaf treatment, respectively. On the other hand, microbial N had increased significantly in the RC of the rice bran and rice straw treatments (11 mg and 5.5 mg, respectively) and insignificantly in the RC of the beech leaf treatment (0.06 mg). This increase amounted to 221% (rice bran), 129% (rice straw) and 1.7% (beech leaves) of the decrease in inorganic N within 10 mm of each RC. Thereafter the rate of N mineralization exceeded that of immobilization, and inorganic N levels had recovered almost to their original level by 15 days (rice bran) and 30 days (rice straw and beech leaves). These results suggested the predominance of biotic immobilization in soil near rice bran and rice straw and of abiotic immobilization in soil near beech leaves. No significant increase in both microbial and soluble organic N in the vicinity of beech leaves after incubation for 5 days further suggested that the abiotic process was responsible for the transformation of inorganic N into the insoluble organic N.     

Microbial Immobilization and Plant Uptake of Different N Forms in Three Forest Types in Shikoku District, Southern Japan

Soil microbial immobilization and plant uptake of N were evaluated for three forest types in Kochi, Shikoku district. During 196-d laboratory incubation, soil NO₃-N production in the Hinoki cypress forest was negligible for the initial 40 d and then rapidly increased, whereas NO₃-N production was rapid from the beginning in Japanese cedar and deciduous hardwood forests. Microbial immobilization of the labeled ¹⁵N decreased in the order of NH₄-N>glycine-N>NO₃-N. The ¹⁵N immobilization was higher for soil in the Hinoki cypress forest than other two soils. The delayed NO₃-N production in the Hinoki cypress forest was likely related with low availability of NH₄-N due to NH₄-N immobilization and substantial NO₃-N immobilization. In the field experiment, ¹⁵N uptake by roots decreased in the order of NH₄-N>NO₃-N>glycine-N. The absorption of the labeled ¹³C suggested direct uptake of organic N. The preference of N forms by root uptake was not different among forest types. Trees in three forest types can absorb inorganic and organic forms of N, suggesting trees absorb the N form that is the most abundant in the soil.     

Field immobilization using alfaxalone and alfaxalone–medetomidine in free-ranging koalas (Phascolarctos cinereus): a randomized comparative study

ObjectiveTo characterize and compare two intramuscular drug protocols using alfaxalone and alfaxalone–medetomidine combination for the field immobilization of free-ranging koalas.Study designBlinded, randomized, comparative field study.AnimalsA total of 66 free-ranging koalas from the Mount Lofty Ranges, South Australia.MethodsKoalas were randomly allocated into two groups. Group A animals were given alfaxalone alone at 3.5 mg kg^–1. Group AM animals were given alfaxalone 2 mg kg^–1 and medetomidine 40 μg kg^–1, reversed with atipamezole at 0.16 mg kg^–1. Blinded operators recorded heart rate (HR), respiratory rate (f_R), cloacal temperature, depth of sedation and times to: first effect, sedation suitable for clinical interventions, first arousal and full recovery. Data were analysed using independent t test, Mann–Whitney U test, chi-square analysis and log-rank test at 5% level of significance.ResultsSuitable immobilization for clinical examination and sample collection was achieved in all animals. In groups A and AM, median time to working depth was 6.5 minutes (range: 3.4–15) and 8.1 minutes (range: 4.3–24) and time to complete recovery was 66 minutes (range: 12–138) and 34 minutes (range: 4–84), respectively, following reversal. Time to first effect was significantly shorter in group A (p = 0.013), whereas time to full arousal was significantly shorter in group AM (p = 0.007) probably due to the administration of atipamezole. Maximum HR was 117 ± 28 beats minute^–1 in group A, which was a significant increase from baseline values (p < 0.0001), whereas group AM showed a significant tachypnoea of 67 ± 25 (normal f_R 10–15; p < 0.0001).Conclusions and clinical relevanceBoth the protocols produced immobilization, enabling clinical examination and sample collection; however, protocol AM was more suitable for field work due to shorter recovery times.     

固定化微生物脂肪酶粉转化生物柴油研究

采用两种转酯方案进行脂肪酶粉转化生物柴油研究,游离脂肪酶在转酯方案一中转酯效率较高为90.15％,在转酯方案二中转酯效率为52.51％.通过壳聚糖和硅藻土对脂肪酶粉固定化并在转酯方案一中的研究发现,硅藻土固定化酶的平均转酯效率高于壳聚糖固定化酶.两种固定化脂肪酶的循环转酯试验表明,随循环次数的增加,水解酶活和转酯效率均逐渐降低,并呈现显著的相关性.     

Behavioral and cardiopulmonary effects of dexmedetomidine–midazolam and dexmedetomidine–midazolam–butorphanol in the silver fox (Vulpes vulpes)

Objective

To evaluate the behavior and some cardiopulmonary variables of dexmedetomidine–midazolam or dexmedetomidine–midazolam-butor-phanol in the silver fox (Vulpes vulpes).

大孔树脂吸附-交联法固定脂肪酶

【目的】为基于大孔树脂吸附结合环氧交联剂交联法固定脂肪酶等工业用酶奠定基础。【方法】使用大孔树脂吸附,而后环氧交联剂交联的方法进行脂肪酶的固定化,研究各因素对吸附–交联固定化的影响,并采用响应面法对固定化条件进行优化,制备固定化酶并考察其稳定性。【结果】筛选出大孔树脂HPD750为载体,聚乙二醇二缩水甘油醚为交联剂。最佳固定化条件为:吸附温度45℃,给酶量60 mg·g–1,交联温度30℃,交联时间12.5 h,pH6.36,交联剂体积分数为0.7%。由上述条件制备所得的固定化酶活力为565.31 U·g–1,酶活力回收率为32.16%。与游离酶相比,固定化酶的热稳定性和酸碱稳定性均有明显提升;连续操作10次,固定化酶活力仍保留34.86%,操作稳定性较好;4℃条件下储存30 d,固定化酶活力仍保留64.81%。【结论】大孔树脂HPD750为载体,聚乙二醇二缩水甘油醚为交联剂制备的固定化脂肪酶热稳定性、酸碱稳定性均得到显著提升,且具有良好的操作及储存稳定性。     

不同钝化剂对铅锌矿区周边农田镉铅污染钝化修复研究

采用大田试验和盆栽试验,研究了海泡石(S)、石灰(L)、腐植酸(H)、生物炭(B)和钙镁磷肥(P)对云南某铅锌矿区周边玉米农田的修复效果,并采用BCR形态分级试验研究土壤钝化前后重金属形态的变化。结果表明:石灰和海泡石可显著提高土壤pH。钝化处理可显著降低DTPA提取态Cd、Pb含量,盆栽试验中,生物炭45 t·hm~(-2)处理对Cd钝化效率可达45.3%,石灰2.25 t·hm~(-2)处理对Pb钝化效率可达60.6%;大田试验中,钙镁磷肥3 t·hm~(-2)处理对Cd最高钝化效率可达48.3%,石灰4.5 t·hm~(-2)处理对Pb钝化效率可达25.3%。石灰、海泡石和生物炭对重金属形态变化影响显著,可促进重金属由高活性形态向低活性形态转换。钝化处理可显著降低玉米籽粒中Cd、Pb含量,生物炭22.5 t·hm~(-2)处理下,Cd最大降幅85%,作物达到食品安全国家标准(GB 2762—2012,Cd≤0.1 mg·kg-1),石灰4.5 t·hm~(-2)处理下,Pb最大降幅59.6%,但未达到食品安全国家标准(GB 2762—2012,Pb≤0.2 mg·kg-1)。部分钝化剂可以起到增产的作用,腐植酸22.5 t·hm~(-2)处理下可增产29.1%。综合分析不同钝化剂及其施用量的效果可知,海泡石和石灰是对该矿区周边Cd、Pb污染农田修复效果最佳的钝化剂,最佳施用量分别为海泡石45 t·hm~(-2)和石灰2.25 t·hm~(-2)。     

Chemical and organic immobilization treatments for reducing phytoavailability of heavy metals in copper‐mine tailings

This study was conducted to evaluate the efficiency of diammonium phosphate (DAP), agricultural limestone (lime), and green‐waste compost mixed with 30% treated sewage sludge (GCS) applied alone or in combination as chemical immobilization treatment using tomato as a test crop. Mine waste was collected from an abandoned copper‐mine tailing site at Mynydd Parys, Anglesey (UK). Lime was applied at the rate of CaCO₃ equivalent (CCE, pH = 7), DAP at the rate of 23 g P per kg substrate, and 10% by weight, GCS as sole application. Half rate of each amendment was also tested as a combined treatment and an untreated substrate (control). Plant‐available metals (Cd, Cu, Fe, Pb, and Zn) were measured in substrate with conventional diethylenetriaminepentaacetic acid (DTPA) and sequential Ca(NO₃)₂ extraction. Plant–dry biomass yield was significantly (p < 0.001) increased by the combined application of all the three amendments while sole application of DAP reduced yield by 4‐fold compared to unamended soil probably due to P toxicity. Addition of lime reduced the DTPA‐extractable Cu, Fe, and Zn by 75%, 81%, and 85%, respectively, while Pb availability was reduced by 88% in combined DAP + lime + GCS treatment compared to control. The extraction capacity of DTPA was higher than that of Ca(NO₃)₂ by 3‐fold for Cu and Fe, 8‐fold for Pb, and 2‐fold for Zn. The leaf‐tissue concentrations of Cu and Fe were reduced by 77% and 83% in the lime + GCS amendment, respectively, while both Pb and Zn were reduced by 89% and 33%, respectively, in substrate treated with the combined application of all three amendments. These results suggest that alkaline amendments (both lime and GCS) were effective in reducing the phytoavailability of Cu, Fe, and Zn while DAP mixed with either GCS or lime was effective in reducing Pb availability.     

黑麦品种间耐铝差异性机制研究

采用室内模拟方法,研究了铝诱导黑麦根系分泌有机酸、根尖磷对铝的固定作用。结果表明,在铝胁迫下冬牧品种（Win）相对根伸长率高于King品种。在铝胁迫下,经磷预处理的根尖铝和磷含量增加,且以Win品种根尖中的Al、P含量较高,说明根尖磷对铝的固定是黑麦耐铝机制之一。另一方面,在铝胁迫下,两品种根系均分泌柠檬酸和苹果酸,且Win的分泌速率较高。有机酸的分泌随着铝处理浓度（10、30、50 mol/L）和时间（0.5、3、6、9、12 h）的增加而增加,但在低温（4C）下柠檬酸分泌量显著减少。Al处理0.5 h后苹果酸已明显分泌,而柠檬酸的分泌在铝处理6 h后才明显增加。在铝处理前,进行缺磷预处理（3 d）不能增加有机酸的分泌,10 mol/L的La3+、Cu2+、Ni3+也不能诱导根系分泌有机酸。说明铝诱导根系专一性分泌有机酸也是黑麦品种间耐铝性差异的机制。