浅谈影响甘蔗光降解地降解的因素

经曝晒试验、田间覆盖栽培试验和一系列的测试分析,结果表明：甘蔗光降解地膜的降解受多种因素的影响,包括光敏剂的使用、气候环境因素、所栽培作物以及栽培制度等。光敏剂的作用是主要的,通过调整光敏剂和有关助剂的用量可以控制光降解地膜的降解速度。太阳光中紫外线的照射能引起光氧化反应,使光降解膜中聚乙烯分子链断裂,地膜脆化,出现裂口,进而降解、破碎消失。栽培作物的遮荫和地下水活动会减我降解膜的降解速度。覆膜后     

甘蔗除草地膜全膜覆盖栽培技术应用效果及存在问题与对策

介绍了甘蔗除草地膜全膜覆盖栽培技术应用效果,认为甘蔗全膜覆盖栽培技术配合甘蔗除草地膜技术对甘蔗栽培节本增效显著,同时阐述了该栽培技术推广过程中存在问题,如除草、残留地膜污染、整地质量等问题,并提出了解决措施,建议使用甘蔗除草光降解地膜替代不可降解的除草地膜。     

用即弃聚丙烯纺粘法非织造布的可光降解研究

通过在聚丙烯中加入掺杂1%(质量分数)Cu2+的锐钛矿型纳米TiO2作为光敏剂,采用纺粘法设备制备TiO2光敏剂含量为0.0%~1.2%的聚丙烯纺粘法非织造布。将其置于70℃、340 nm紫外光下进行光降解试验,研究样品的力学性能、结晶度和表面形态的变化。结果表明:在聚丙烯中加入Cu2+掺杂的锐钛矿型纳米TiO2,可以催化聚丙烯纺粘法非织造布的光氧化降解和加快降解速度,且在实验范围内光敏剂的含量越大,其光催化降解作用越强。     

光降解甘蔗除草地膜研究报告（Ⅰ）

通过三年的田间试验,筛选出适用于湛江蔗区的光降解除草地膜配方,经过用紫外线曝辐和自然曝晒等方法处理。从分析断裂伸长率、粘均分子量和羰基吸收峰的变化,说明降解的降降解速度,比对照膜要明显加快。所选Ｔ１、Ｔ２、Ｔ３和１１２四个配方可适用于广东省雷州半岛蔗区使用,使用光降解膜完全能代替普通会影响甘蔗苗期生长和产量。能实现盖膜６０天后才破裂,甘蔗培土埋膜露光部分可以硫裂到４×４ｃｍ＾５２以下,当年的残膜减     

生物降解地膜在果蔗的田间应用效果研究

广东省果蔗种植上普遍采用果蔗齐苗后揭除普通地膜培土的方式,这种方式极为浪费劳动力,也增加残膜处理工序及成本。应用生物降解地膜可以免除揭膜工序,具有轻简栽培作用。为了探讨生物降解地膜在轻简栽培模式下在广东省果蔗上的应用效果,2019～2020年在广州市南沙区实施不同地膜的大田对比试验,研究生物降解地膜的降解效果和对果蔗生长及产量的影响。结果表明,生物降解地膜在果蔗生长不同阶段的农艺性状差异不大;生物降解地膜较普通地膜处理的果蔗产量增产5.25%。生物降解地膜机械性能和水蒸气透过率满足国标要求,其初始力学性能满足果蔗的机械覆膜要求,其水蒸气透过率高于普通地膜,但不影响果蔗齐苗生长。到果蔗收获时,生物降解地膜已完全降解。与揭除地膜比较,生物降解地膜不揭膜,其果蔗产量仅减产6.78%;普通地膜不揭膜,其果蔗产量减产达到23.66%。生物降解地膜不仅满足果蔗轻简栽培的使用要求,且能够解决蔗田残膜面源污染问题,属于绿色环保型的农资产品。     

氧化-生物双降解膜对土壤水热变化及烟株生长的影响

为减轻烟田地膜覆盖产生的白色污染，通过田间对比试验探讨氧化-生物双降解地膜替代常规地膜的可行性。试验设置常规地膜不揭膜（CK0）、适时揭膜（CK1）、降解速度不同的氧化-生物降解膜A(T1)、B(T2)、C(T3)共5个处理，研究了降解膜的降解状况、膜下土壤水热变化、烤烟生长发育状况以及经济效益。结果表明，所有降解膜在烟株生育期内均全部降解，T3处理降解膜在烟株移栽后22 d和39 d进入开裂期和大裂解期，较T1、T2处理开裂时间晚，开裂程度低，移栽后0～35d，膜下土壤温度、含水量高于T1、T2处理，增温保墒效果接近于CK0；在移栽35d以后，与CK1相比，仍具有一定的保温效果；烟株长势以及经济效益均优于T1、T2，与CK0和CK1等同。综上，团棵期前开裂程度低、烟株生育期内能够全部降解的氧化-生物降解膜C替代常规地膜具有可行性。     

甘蔗光降解地膜的试验与推广应用

本文总结了甘蔗光降解地膜在湛江农垦集团公司所属蔗区的试验、示范及推广情况,并提出在推广应用中所需注意的问题及解决方法,旨在推进甘蔗光降解地膜的完善工作,以利于甘蔗光降解地膜在广东蔗区的大面积推广使用。     

酒精润版液研究

在平版胶印过程中,始终保持印版非图文部分被水润湿是非常必要的,只有用水全面覆盖印版空白部分,使其有效斥墨,才能准确传递图文。目前,国内大多数印刷厂使用阳图型 PS 版进行制版印刷,其非图文区域是感光区域,这一区域的感光膜在晒版过程中受到紫外线照射后,由于光敏剂的作用引发光降解反应,通过碱性显影液处理可将已降解部分的感光膜彻     

可控光、生物降解塑料薄膜工业化生产及应用研究

论述了光、生物降解塑料薄膜的光敏剂研制和生物降解专用料的超细、活化与表面处理及双降解母粒、薄膜的工业化生产。研究了双降解母粒和膜的生产工艺与性能,测定了双降解LDPE膜UV光照加速过程羰基指数变化和自然暴露过程分子量的变化,进行了ASTM微生物的试验,双降解膜物理机械性能与堆埋时间关系的试验,并进行了推广应用研究。     

可控光、生物降解塑料薄膜工业化生产及应用研究

论述了光、生物降解塑料薄膜的光敏剂研制和生物降解专用料的超细、活化与表面处理及双降解母粒、薄膜的工业化生产.研究了双降解母粒和膜的生产工艺与性能,测定了双降解LDPE膜UV光照加速过程羰基指数变化和自然暴露过程分子量的变化,进行了ASTM微生物的试验,双降解膜物理机械性能与堆埋时间关系的试验,并进行了推广应用研究.     

Comparison of Alfalfa-Orchardgrass Hay Stored in Large Round Bales and Conventional Rectangular Bales for Lactating Cows

Lactating Jersey cows were used in two trials to evaluate alfalfa-orchardgrass hay baled and stored by the following methods: 1) conventional rectangular bales; 2) large round bales, stored inside; and 3) large round bales, stored outside. Half the round bales stored outside in trial 1 were stored on automobile tires and the other half were stored on the gound. In trial 2, half of the bales stored outside were partially covered with plastic caps and the other half were exposed to the weather. Covariance adjusted milk production was significantly higher for inside over outside storage in trial 1 and for conventional over round bales and covered over exposed in trial 2.In trial 1, utilization by cows as a percent of dry matter baled was 92.9, 74.0, and 66.6% for round bales stored inside, stored outside on tires, and stored outside on the ground. Percents were 86.8, 88.8, and 65.0% for round bales stored inside, stored outside covered, and stored outside exposed in trial 2. Storing round bales on automobile tires effectively reduced bottom spoilage. Covers of polyethylene film reduced weather deterioration and feeding waste of covered bales to amount of bales stored inside.     

In situ dry matter and crude protein degradation of fresh forages during the spring growth.

We compared ruminal dry matter (DM) and crude protein (CP) degradation kinetics of fresh forages of alfalfa (vegetative, early bud, early flowering, and late flowering stages) and bromegrass with endophyte-free and endophyte-infected tall fescue (tillering, stem elongation, heading, and flowering stages) by using nonlinear models. Duplicate Dacron bags were incubated for 0, 3, 6, 9, 12, 16, 24, 36, 48, and 60 h in 2 Simmental x Angus steers fitted with ruminal cannulas. The effects of animal, forage species, and maturity within forage species were evaluated. A first-order kinetics model was determined to be suitable for estimation of degradation profiles relative to models with variable rate of degradations. Alfalfa had higher soluble DM (36.6%), lower insoluble potentially digestible DM (43.0%), higher rate (13.8%/h), and higher extent of DM degradation (66.3%) than grasses (27.2, 53.5, 6.7%/h, and 54.6% for soluble DM, insoluble potentially digestible DM, rate, and extent of DM degradation, respectively). The extent of CP degradation was similar among forages (74.7%), but alfalfa had a higher CP degradation rate than grasses (16.1 vs. 12.5%/h). Extents of degradation of DM and CP decreased with maturity in alfalfa and in grasses. Ruminally undegradable CP (RUP) was higher in alfalfa (40.0 g/kg of DM) than in grasses (34.9 g/kg of DM), and decreased with maturity in grasses (40.4 to 28.3 g/kg of DM) but not in alfalfa. The amount of RUP that was potentially degradable in the rumen was not different among forage species (22.1 g/kg). As forage CP concentration decreased, the RUP (as a percentage of CP) increased but, as a percentage of forage DM, decreased. Species of forage had important effects on ruminal DM and CP degradation when incubated in fresh form.     

甘油对大豆分离蛋白/海藻酸钠复合膜热分解的影响

本文采用流延法制备了一系列甘油增塑、与海藻酸钠共混改性的大豆分离蛋白/海藻酸钠复合膜,并利用热重分析方法对这些复合膜的热分解性能进行了考察.热分解实验中,通过改变升温速率,研究甘油含量对大豆分离蛋白/海藻酸钠复合膜热分解性能的影响.从所得到的TGA和DTA曲线可知,大豆分离蛋白/海藻酸钠复合膜的热分解行为可以分为三个较明显的降解阶段.根据失重速率的变化确定热分解反应最剧烈的温度区间为420 ～630K,对此采用Coats-Redfern方法进行了热分解动力学分析,并得出该阶段为一级热分解反应的结论.通过动力学模型,可以计算得到这些复合膜热分解反应的动力学参数,如表观活化能和指前因子.实验结果显示,甘油的加入使复合膜更易热分解;计算也表明热分解活化能随着甘油量的增加而不断下降,降幅可达50％.     

Effect of different levels of rapidly degradable carbohydrates calculated by a simple rumen model on performance of lactating dairy cows

Aggregating rumen degradation characteristics of different carbohydrate components into the term modeled rapidly degradable carbohydrates (mRDC) can simplify diet formulation by accounting for differences in rate and extent of carbohydrate degradation within and between feedstuffs. This study sought to evaluate responses of lactating dairy cows to diets formulated with increasing levels of mRDC, keeping the supply of other nutrients as constant as possible. The mRDC content of feedstuffs was calculated based on a simple rumen model including soluble, washable, and nonwashable but potentially degradable fractions, as well as the fractional degradation and passage rates, of sugar, starch, neutral detergent fiber, and other carbohydrates. The mRDC term effectively represents the total amount of carbohydrates degraded in the rumen within 2 h after ingestion. Fifty-two lactating Holstein cows (of which 4 were rumen fistulated) were assigned to 4 treatments in a 4 × 4 Latin square design. Treatments were fed as a total mixed ration consisting of 25.4% corn silage, 23.1% grass silage, 11.6% grass hay, and 39.9% concentrate on a dry matter basis. Differences in mRDC were created by exchanging nonforage neutral detergent fiber-rich ingredients (mainly sugar beet pulp) with starch-rich ingredients (mainly wheat) and by exchanging corn (slowly degradable starch) with wheat (rapidly degradable starch) in the concentrate, resulting in 4 treatments that varied in dietary mRDC level of 167, 181, 194, or 208 g/kg of dry matter. Level of mRDC did not affect dry matter intake. Fat- and protein-corrected milk production and milk fat and lactose yield were greatest at 181 mRDC and decreased with further increases in mRDC. Milk protein yield and concentration increased with increasing mRDC level. Mean rumen pH and diurnal variation in ruminal pH did not differ between treatments. Total daily meal time and number of visits per meal were smaller at 181 and 194 mRDC. Despite milk production responses, increasing dietary mRDC levels, while maintaining net energy and intestinal digestible protein as well as other nutrients at similar levels, did not influence rumen pH parameter estimates and had minor effects on feeding behavior. These results indicate that aggregating rapidly degradable carbohydrate content into one term may be a simple way to further improve predictability of production responses in practical diet formulation for lactating dairy cows.     

Milk yield and composition of dairy cows fed concentrate based on naked oats.

A 1.5-yr study was designed to determine the effects of feeding isonitrogenous and isoenergetic concentrates based on naked oats, corn, or a mixture (50: 50 on as-fed basis) of naked oats and corn on milk yield and composition. In vitro dry matter (DM) digestibility and ruminal degradabilities of DM, N, and starch of naked oats were compared with those of covered oats. Twenty-seven multiparous Holstein cows were blocked by similar calving date and assigned to 9 replicates. All cows were fed a mixture of grass silage, protein supplement, concentrate, and a vitamin and mineral mix for ad libitum intake. Treatment diets were fed from 3 to 36 wk of lactation. Milk yield and composition, yield of 4% fat-corrected milk, and yield of protein and fat were similar among treatments. Ruminal effective degradabilities of DM were higher for naked oats than for covered oats, but the ruminal degradabilities of crude protein and starch were similar. The rapidly degradable fractions of DM, crude protein, and starch were greater for naked than covered oats; the potentially degradable fractions were less. In vitro DM digestibility of naked oats was higher than was that of covered oats. Naked oats may be a good alternative to corn for milk yield.     

Ensiling characteristics and ruminal degradation of Italian ryegrass and lucerne silages treated with cell wall-degrading enzymes

Two experiments were carried out to investigate the effect of added cell wall-degrading enzymes at ensiling on the fermentation and in situ degradation of grass and legume silages. Primary growths of Italian ryegrass (Lolium multiflorum Lam) and lucerne (Medicago sativa L) were wilted and ensiled in laboratory-scale silos with or without enzymes. Silages were opened at 2, 5, 15 and 45 days after storage; the fermentation quality and the contents of cell wall components (NDF, ADF, ADL) were determined. The 45 day silages were subjected to in situ incubation experiments, and the kinetics of DM and NDF degradation was estimated. The enzyme treatment enhanced the lactic acid production (P < 0.01) and reduced the pH value (P < 0.01) of both Italian ryegrass and lucerne silages. The contents of cell wall components, however, were not affected by enzymes, except for NDF of Italian ryegrass silage. The in situ incubation experiments revealed that added enzymes increased the rapidly degradable DM (P < 0.01) and appeared to decrease the rate of degradation of DM and NDF of Italian ryegrass silage. The rapidly degradable DM was not altered when lucerne was treated, but the rate of degradation of NDF was significantly reduced (P < 0.05). These results suggest that although added cell wall-degrading enzymes could improve the preservation of grass and legume silages, the effects on ruminal degradation may be different according to the herbage treated. Enzymatic hydrolysis during ensilage may be restricted to easily digestible cell walls, leaving relatively less digestible components that would be retained in treated silages. © 1999 Society of Chemical Industry     

In vitro degradation of choline from selected feedstuffs and choline supplements

The objective of this experiment was to determine the extent of in vitro degradation of choline from barley, corn, corn gluten meal, cottonseed meal, fish meal, soybean meal, alfalfa hay, timothy hay, choline chloride, and choline stearate. During four individual fermentation runs, samples were incubated in vitro for .25, 1, 3, 6, 12, 18, 24, 36, and 48 h with an inoculum mixture containing rumen fluid obtained from a rumen-fistulated dairy cow fed 17.5% corn silage and 28.7% grass silage and 53.8% concentrate diet. Because of their low choline content (less than .68 mg/g) corn, corn gluten meal, alfalfa hay, and timothy hay gave erratic values for choline disappearance for different fermentation runs and times of incubation although disappearance tended to increase with time. Data for the rest of the feeds and choline supplements were analyzed using nonlinear regression procedure to obtain estimates of potentially degradable choline, rapidly degradable choline, and the rate of choline degradation in vitro. The mean estimates of rumen degradable choline (%) were 79.4, 84.7, 82.9, 83.8, 98.0, and 98.6 for barley, cottonseed meal, fish meal, soybean meal, choline stearate, and choline chloride, respectively. The results suggest that incorporating choline-rich feedstuffs in diets can only marginally increase the postruminal flow of choline in dairy cows.     

Comparative oxidation and net emissions of methane and selected non-methane organic compounds in landfill cover soils

The surface emissions of methane (CH4) and non-methane organic compounds (NMOCs) were determined at two different areas at a French landfill: a permanently covered and fully vegetated area (40 cm coarse sand + 80 cm of loam) and a temporarily covered area (40 cm of coarse sand). The 37 NMOCs quantified in the landfill gas samples included alkanes (C1-C10), alkenes (C1-C4), halogenated hydrocarbons (including (H)CFCs), and aromatic hydrocarbons. Both positive and negative CH4 fluxes ranging from -0.01 to 0.008 g m(-2) d(-1) were measured from the permanently covered cell. However, high spatial variation was observed, and a hot spot with a high flux (10 g m(-2) d(-1)) was identified. A higher CH4 emission occurred from the temporarily covered cell (CH4 flux of 49.9 g m(-2) d(-1)) as compared to the permanently covered cell. The NMOC fluxes from the permanently covered zone were all very small with both positive and negative fluxes in the order of 10(-7) to 10(-5) g m(-2) d(-1). Higher and mainly positive NMOC fluxes in the order of 10(-5) to 10(-4) g m(-2) d(-1) were obtained from the temporarily covered zone. The lower emission from the permanently covered and fully vegetated cell was attributable to the thicker soil layer, which functions as microbial habitat for methanotrophic bacteria. The NMOC oxidation capacity was investigated in soil microcosms incubated with CH4. Maximal oxidation rates for the halogenated aliphatic compounds varied between 0.06 and 8.56 microg (g of soil)(-1) d(-1). Fully substituted hydrocarbons (tetrachloromethane, perchloroethylene, CFC-11, CFC-12, and CFC-113) were not degraded in the presence of CH4 and O2. Benzene and toluene were rapidly degraded, giving very high maximal oxidation rates (28 and 39 microg (g of soil)(-1) d(-1)). On the basis of the emission measurements and the batch experiments conducted, a general pattern was observed between emissions and biodegradability of various NMOCs. The emissions mainly consisted of compounds that were not degradable or slowly degradable, while an uptake of easily degradable compounds was registered. As an example, perchloroethylene, trichloromethane, CFC-11, and CFC-12 were emitted, while atmospheric consumption of aromatic hydrocarbons and lower chlorinated hydrocarbons such as vinyl chloride, dichloromethane, and chloromethane was observed. This study demonstrates that landfill soil covers show a significant potential for CH4 oxidation and co-oxidation of NMOCs. Under certain conditions, landfills may even function as sinks for CH4 and selected NMOCs, like aromatic hydrocarbons and lower chlorinated compounds.     

Do potential methylation rates reflect accumulated methyl mercury in contaminated sediments?

Relationships between the short-term mono-methyl mercury (MeHg) production, determined as the specific, potential methylation rate constant Km (day(-1)) after 48 h of incubation with isotope-enriched 201Hg(II) at 23 degrees C, and the long-term accumulation of ambient MeHg, were investigated in contaminated sediments. The sediments covered a range of environments from small freshwater lakes to large brackish water estuaries and differed with respect to source and concentration of Hg, salinity, primary productivity, quantity and quality of organic matter, and temperature climate. Significant (p < 0.001), positive relationships were observed between Km (day(-1)) and the concentration of MeHg normalized to total Hg (%MeHg) for surface sediments (0-10, 0-15, and in one case 0-20 cm) across all environments, and across subsets of organic and minerogenic freshwaters. This suggests that the methylation process (MeHg production) overruled demethylation and net transport processes in the surface sediments. The lack of a relationship between Km and %MeHg in two brackish water sediment depth profiles (0-100 cm) indicates that demethylation and the net effect of input-output are relatively more important at greater depths. Differences in the primary production and subsequent availability of easily degradable organic matter (serving as electron donor for methylating bacteria) was indicated to be the most important factor behind observed differences in %MeHg and Km among sites. In contrast, concentrations of sulfate were not correlated to Km, %MeHg, or absolute concentrations of MeHg. We conclude that total concentrations of Hg are of importance for the long-term accumulation of MeHg, and that %MeHg in surface sediments can be used as a proxy for the rate of methylation, across a range of sites from different environments.     

Ruminal in vitro degradability of protein in alfalfa harvested as standing forage or baled hay.

Eighty-nine samples, 45 of standing forage and 44 of baled hay, were collected from alfalfa harvested at various maturities over three cuttings each during 2 yr. Alfalfa was cut and conditioned mechanically; samples of standing forage were collected by removing bunches of forage from windrows and freeze-drying them. Forage was allowed to field cure and was harvested at an average 80% DM as small rectangular bales; samples of baled hay were collected by coring bales after storing for 3 to 6 mo. Samples were analyzed for DM, ADF, total N, fractions of total N present as ADIN, N degraded at 0 h, and potentially degradable protein N. Ruminal protein degradation rates and escapes were estimated using an inhibitor in vitro system, assuming that ADIN was unavailable and that ruminal passage rate was .06/h. Standing forage contained smaller fractions of ADIN and N degraded at 0 h, contained a larger fraction of potentially degradable N, and had more rapid degradation rates and lower estimated protein escapes than baled hay. Mean degradation rates and estimated escapes were .171/h and 24% for standing forage and .075/h and 40% for baled hay. There were no differences in degradation rate or estimated escape because of harvest year, and neither was significantly related to maturity or to ADF concentration. Results indicate a significant advantage in ruminal protein escape, compared with grazed alfalfa, for alfalfa harvested and stored as hay.