浅析酸雨对菜园土硝态氮淋失的影响

通过土柱模拟酸雨淋溶试验，研究了施用等复合肥量条件下，不同酸度模拟酸雨以及降雨量对菜园土硝态氮淋失的影响。结果表明，不同酸度模拟酸雨处理下淋滤液硝态氮浓度均随淋溶次数的增加呈不断下降趋势，淋滤液硝态氮浓度最大值为292.9 mg/L(pH=2.0，第1次淋滤液)，最小值为93.7 mg/L(pH=6.5，第8次淋滤液)。随着淋洗次数的增加，淋滤液硝态氮浓度降低。试验结果还表明，不同淋洗处理硝态氮的淋失总量均较大，在403.0～649.0 mg之间，其大小顺序为pH 2.0>pH 3.0>pH 4.0>pH 5.0>pH 6.5，随酸雨pH值降低，硝态氮淋失量增大，强酸性降水加剧菜园土中硝态氮淋失。不同淋洗处理对菜园土壤硝态氮累计淋失量的动态变化特征没有大的影响，硝态氮累计淋失量均随着淋溶次数增加不断增大，但不同pH值模拟酸雨对菜园土壤硝态氮的累计量淋失影响很大。     

酸雨对贵阳城区地表磷淋洗溶出效应研究

模拟贵阳市2005年酸雨情况,利用土柱淋洗试验,研究贵阳市三个不同区域磷淋失的动态变化特征,为本地区农业合理施肥和水体富营养化防治提供科学依据。研究结果表明,磷淋失与酸雨pH值和降雨量密切相关,酸雨pH值越小,酸性越强,磷淋失量越大;降雨量越大,磷淋失量也越大。     

氧化石墨烯/二氧化锰的制备及应用

以氧化石墨烯、氯酸钡和硫酸锰为原料合成氧化石墨烯/二氧化锰(GO/MnO2).通过研究投加量、pH值、Pb2+的浓度对去除率的影响,探究材料对水体中Pb2+的吸附特性.结果表明,投加量为0.2g/L,pH=7时,GO/MnO2对20mg/L的Pb2+的去除效率最高达到96.92％.同时对GO/MnO2进行SEM和XRD...     

不同组分酸雨对水稻土镉、铜、铬的释放研究

在离子强度、pH值相同的情况下,采用一年雨量不同摩尔浓度比值的硫酸根、硝酸根模拟酸雨进行土柱淋滤的模拟试验,研究不同比值的模拟酸雨对珠三角水稻土Cd、Cu、Cr毒性元素释放的影响。研究表明:在离子强度不变的情况下,Cd、Cu、Cr在不同的SO2-4、NO-3摩尔浓度比下有不同的淋溶行为,借此可以评估硫酸型酸雨、硝酸型酸雨对农田生态系统的潜在危害,为预防与治理提供依据。     

不同类型酸雨对水稻土酸缓冲力影响研究

在离子强度、pH值相同的情况下,采用一年雨量不同摩尔浓度比值的硫酸根、硝酸根模拟酸雨进行土柱淋滤的模拟试验,研究不同比值的模拟酸雨对珠三角水稻土酸缓冲能力的影响。研究表明：在保持pH值、离子强度不变的情况下,不同摩尔浓度比的硫酸根、硝酸根模拟酸雨对土壤的酸缓冲力影响不明显。     

pH对13X分子筛去除Pb(Ⅱ)性能的影响研究

探讨了13X分子筛对不同初始pH的Pb(Ⅱ)溶液中Pb(Ⅱ)的吸附量、吸附速率及吸附机理,以及分子筛的碱性对溶液pH的改变。结果表明,1 g/L的13X分子筛的碱性为10^-5mol/g,Pb(Ⅱ)溶液pH为3.0~9.0时,分子筛自身的碱性会使反应溶液pH升高。当Pb(Ⅱ)溶液pH由3.0升高至12.0时,分子筛对Pb(Ⅱ)的去除率由65.1%增大至99.7%。Pb(Ⅱ)溶液pH为5.0~7.0时,13X分子筛对Pb(Ⅱ)的吸附符合拟二级动力学方程,吸附速率k_2由1.72 g/(mmol·min)增大至2.85 g/(mmol·min),而当pH达到Pb(Ⅱ)开始形成沉淀时(pH>7.0),吸附速率显著降低。13X分子筛对Pb(Ⅱ)的去除机理主要为离子交换,当溶液内开始出现Pb(Ⅱ)的沉淀时,离子交换量降低,pH=10时,离子交换量仅占总去除量的30.2%。反应过程中由于13X分子筛自身的碱性和Pb(Ⅱ)易形成羟和配离子的特性,反应体系pH会在pH<7.0形成酸性缓冲区域和8.0~10.0范围内形成碱性缓冲区域。     

酸雨对煤中砷、汞的淋滤特征及分布规律的影响

针对东北某地待开发的2号钻孔煤、820℃灼烧底灰及煤矸石为淋滤实验对象,详细研究了酸雨类型、酸雨酸度、酸雨降雨量对砷、汞的淋出特征及分布规律。结果表明：砷由于其惰性,在原煤及底灰中均淋不出,矸石中淋出率也不高。汞在原煤中淋出率不大于l％,但在底灰中活性很强,在10h内,去离子水的淋出率为54．58％,硫酸型和硝酸型酸雨可将底灰中汞全部淋出;砷、汞在煤矸石中淋滤规律为：洗矸〉矸石山〉顶板,酸雨强度表现为低酸雨强度时对砷、汞有最大淋出;酸雨雨量的增大会导致矸石中汞的淋出成倍增加。     

利用T.f和T.t混合菌进行污泥生物淋滤的研究

通过使用氧化硫硫杆菌和氧化亚铁硫杆菌混合菌进行为期7天的大型生物淋滤,并对在淋滤过程中污泥pH的变化以及重金属含量进行检测,研究了不同接种量对生物淋滤中重金属去除的影响。结果表明,使用10%接种量进行生物淋滤更优于使用5%接种量,且淋滤过后重金属Pb、Cd、Cr、As和Hg的去除率分别达到48.5%、46%、63.65%、66.7%和100%。     

柠檬酸改性白酒糟对Cu、Cd、Cr和Pb的吸附特性研究

以柠檬酸改性白酒糟为吸附剂,考察了pH值、吸附剂投加量、反应时间、吸附质初始浓度等对水中Cu、Cd、Cr和Pb吸附性能的影响,探究了改性白酒糟的等温吸附及吸附动力学特性。结果表明,相对最优的实验条件为pH=4,吸附剂投加量4 g/L,反应时间3 h,吸附质初始浓度60 mg/L;改性白酒糟对Cu、Pb、Cd、Cr的吸附过程更符合准二级动力学方程和Langmuir等温线方程,计算得到理论最大吸附量为Cu 11.19 mg/g, Cd 7.49 mg/g, Cr 5.63 mg/g, Pb 9.36 mg/g。     

GF-AAS法测定庐山区农村饮用水中铅、镉的含量

通过对庐山区农村饮用水进行抽样测定了重金属Pb、Cd的含量,分析重金属Pb、Cd的污染情况。选取有代表性的水样28份,采用石墨炉原子吸收光谱法(GF-AAS)测定饮用其中Pb、Cd的含量。结果表明:28份水样中所含Pb量为(0.2386±0.4124)μg/L,Cd量为(0.0984±0.1456)μg/L。根据《生活饮用水卫生标准》(GB/T5750-2006),Pb限度为10μg/L,Cd限度为5μg/L,28份样本所测的重金属均在其限度范围内,表明庐山区农村饮用水没有重金属Pb、Cd的污染。     

多壁碳纳米管-铋膜电极微分电位溶出法测定涂料中的铅

制备了嵌入式多壁碳纳米管膜玻璃碳电极,研究了铅在电极上的电位溶出行为,建立了嵌入式碳纳米管-铋复合膜电极测定铅的微分电位溶出分析法。结果表明:富集电位为-1.1 V,HAc-NaAc(pH=4.60)缓冲溶液中,峰高与铅浓度在0.1～20.0μg/L范围呈线性,检出限为0.5μg/L,对实际样品进行测定,相对标准偏差(RSD)值在3.8%～7.1%之间,回收率在95.2%～98.7%之间。     

The influence of soil properties on the effectiveness of phenylphosphorodiamidate (PPD) in reducing ammonia volatilization from surface applied urea

Urea can be an inefficient N source due to rapid hydrolysis by soil urease leading to NH₃ volatilization. The current study investigated the effect of the urease inhibitor phenylphosphorodiamidate (PPD) incorporated at two concentrations (0.5% and 1% w/w) within the fertilizer granule on NH₃ volatilization from surface applied urea. The daily rates of NH₃ loss from 20 soils of widely differing properties from Northern Ireland were measured over 14 days using ventilated enclosures under simulated spring conditions. Cumulative loss rates were calculated and fitted to a logistic model from which total NH₃ loss (Amax) and the time to maximum rate of loss (Tmax) were determined. Stepwise multiple linear regression analysis related the effectiveness of PPD in reducing NH₃ volatilization from urea to soil properties.The total cumulative loss of ammonia from unamended urea varied from 0.37 to 29.2% depending on soil type. Ammonia volatilization appeared to be greatest on a soil with a high pH (R² = 0.65), a low titratable acidity (TA) (R² = 0.63) and a soil that was drying out (R² = 0.50). Soil pH was negatively correlated with TA (r = –0.826, P < 0.001) suggesting that soils with a low TA may have received recent lime. Including cation exchange capacity (CEC) and % N as well as pH-KCl in the multiple linear regression equation explained 86% of the variance.The effectiveness of PPD in reducing Amax varied between 0% to 91% depending on soil type, the average over all 20 soils being 30 and 36% for 0.5% and 1% PPD respectively. The most important soil properties influencing the effectiveness of the urease inhibitor were soil pH-H₂O and TA accounting for 33% and 29% of the variance respectively. PPD was less effective on a soil with a high pH and low TA. These were the soil conditions that led to high NH₃ volatilization from unamended urea and may explain why PPD had limited success in reducing ammonia loss on these soils. Multiple linear regression analysis indicated that 75% of the variation in the % inhibition of NH₃ loss by PPD could be significantly accounted for by pH-H₂O, initial soil NO ₃ ^- -N concentration, % moisture content and % moisture loss.The delay in Tmax by PPD ranged from 0.19 to 7.93 days, the average over all 20 soils being 2.5 and 2.8 days for 0.5% and 1% PPD respectively. TA, % moisture content, urease activity and CEC were soil properties that significantly explained 83% of the variation in the % delay in Tmax by PPD in multiple linear regression analysis. However, none of these soil properties were significant on their own. As urea hydrolysis occurs rapidly in soil, delaying Tmax under field conditions would increase the chance of rain falling to move the urea below the soil surface and reduce NH₃ volatilization. A urease inhibitor should be more effective than PPD on soils with a high pH and low TA to be successful in reducing high NH₃ losses.     

LS-5000氨基磷酸型螯合树脂吸附Pb~(2+)的研究及应用

研究了LS-5000型氨基磷酸型螯合树脂对Pb2+的吸附性能及在模拟浓缩果汁铅的去除中的应用。结果表明,LS-5000型氨基磷酸型螯合树脂在酸性条件下对Pb2+具有良好的吸附性能,静态吸附平衡时间为1 h,最大吸附量为5 527.45μg/g树脂,负载Pb2+的树脂可用1 mol/L的HNO3解吸,解吸后的树脂可以再利用。LS-5000氨基磷酸型螯合树脂可用于果汁、浓缩果汁中Pb2+的去除,用0.5 g树脂处理50 mL含Pb2+4.0μg/mL果汁,Pb2+的一次去除率可达99%。     

用弗雷德盐去除土壤淋洗液中的镉

用模拟酸雨(pH=4)对高镉土壤(全镉为10.590 mg/kg)进行浸取。实验结果表明,模拟酸雨对土壤中镉的浸出率仅为其总镉的1%左右,但浸出液中镉的含量(0.108 mg/L)仍远高出GB 3838—2002地表水Ⅴ类水质的要求,也高于GB 18918—2002城镇污水处理厂污染物排放标准(<0.01 mg/L),必须予以处理。弗雷德盐是以聚合铝为主要原料人工合成的层状双羟合物,它能以同晶取代、吸附或共沉淀形式去除水体中的重金属镉离子。研究表明,土壤浸出液中大量的Al3+、Fe3+会影响弗雷德盐对淋洗液中镉的去除,但处理后的镉含量仍可达到GB 18918—2002城镇污水处理厂污染物排放标准。     

Eu(MAA)_3Phen-CHIT用于铅离子的测定

在316 nm激发波长下,痕量铅离子的引入可使铕-甲基丙烯酸(MAA)-邻菲罗啉(Phen)三元稀土配合物壳聚糖(CHIT)醋酸(HAc)溶液体系在418 nm的发射荧光产生猝灭现象。在0.5 g/LEu(MAA)3Phen-0.2%CHIT-1%HAc溶液中,随着Pb2+浓度的增大,该体系的荧光强度IF由急剧下降至渐趋稳定。Pb2+浓度在0.1~6μmol/L内,IF呈线性下降,检出限为1.1μg/L。     

DA-6缓解胺苯磺隆对后茬水稻伤害的作用

室内采用土培法分别测定了不同浓度胺苯磺隆和不同浓度己酸二乙氨基乙醇酯(简称DA-6)对水稻生长的影响以及不同浓度胺苯磺隆处理下DA-6对水稻根生长的影响。结果表明,胺苯磺隆处理浓度自0.1μg/kg起,明显抑制水稻幼苗的生长,且对主根长和根鲜重的抑制作用较株高和株鲜重更为严重;当DA-6浓度在0.5~20mg/L范围内,水稻根长和根鲜重高于对照,其中以5mg/L最好;用5mg/L的DA-6浸种可不同程度地缓解0.1~20μg/kg的胺苯磺隆对水稻的伤害。     

HPLC法测定双氯芬酸钾中有关物质

建立了HPLC法测定双氯芬酸钾中的有关物质的方法.采用Kromasil C18(250mm×4.6mm,5μm)色谱柱;以磷酸盐缓冲溶液(其中含0.5g/LH3PO4,0.8g/L NaH2PO4,用磷酸调节pH至2.5)-甲醇(34∶66)为流动相;检测波长257nm;流速1.0mL/min.双氯芬酸钾在0.02～0.10μg范围内线性关系良好(r=0.9999),定量下限为4ng,各种破坏性样品的分离度符合规定.本方法灵敏,准确,能够满足双氯芬酸钾对有关物质测定的要求.     

小球藻对海水中Pb2+的生物吸附研究

研究了小球藻对海水中Pb2+吸附的特性,探讨了吸附热力学和动力学。考察了吸附剂用量、pH值、温度、Pb2+的起始浓度和时间等对吸附的影响。研究表明,在试验浓度范围内,吸附剂的用量对吸附率的影响不大;pH值对吸附影响较大,小球藻吸附Pb2+的适宜pH值为4～6;小球藻对Pb2+吸附的吸附量与其浓度呈正相关;在25 ℃时,小球藻对Pb2+的吸附非常快,60 min达到吸附平衡,其动力学数据符合准二级动力学模型,对Pb2+的吸附可以用Freundlich等温方程来描述,对含铅污染的海水净化处理具有探索性及指导性意义     

Allelopathic substances in ecosystems

Recovery studies were conducted with ferulic acid, a common allelopathic agent, using various soils and soil components. Ferulic acid was placed into sterile soil components (gibbsite, geothite, Georgia kaolin, and Utah bentonite), and different sterile soil materials (from different horizons in the same profile) varying in mineralogy and in organic matter content. The initial concentration of ferulic acid added to the soil materials was 1000 μg/g (5.149 mmol/g). The pH of the soil materials was adjusted and maintained at approximately 4.5 or 7.5. Samples were extracted with 0.03 M EDTA at days, 1, 4, 7, 10, and 13 after addition of ferulic acid. Concentrations of ferulic acid in the extracts were determined with a high performance liquid chromatograph. No breakdown products were detected. Models were developed to describe the recovery of ferulic acid from each soil material and soil component over time. Organic matter was the most active soil component involved in the irreversible retention of ferulic acid. The inorganic soil components were much less active than organic matter but appeared to be similar to each other in activity. Irreversible retention of ferulic acid by soil and soil components was greatest as pH 7.5.