环境温度对污泥堆肥过程的影响

在不同的环境温度下,采用强制通风静态污泥堆肥中试实验系统进行了五种调剂的污泥堆肥实验。结果表明：环境温度对污泥堆肥过程的堆体温度有影响。在寒冷的冬季（气温范围为－15－5．0℃,平均气温为－5．1℃）,污泥堆肥的堆体中层温度能顺利达到温度（60℃）,并能保持一段高温期（约9d),堆肥产品达到了无害化国家标准,在污泥堆肥过程,不必对堆料的pH值进行调整。     

投加方式和通风速率对脱水污泥堆肥效果的影响

为了在降低能耗的前提下获得更高的污泥堆肥效率和提高堆肥产品质量,利用梨形筒式好氧堆肥反应器,设置2种物料投加方式和3种通风速率,研究堆肥过程中温度、含水率、总氮以及发芽指数(GI)的变化特性。结果表明,与间歇式堆肥相比,连续式堆肥可以显著提高堆体温度和堆体腐熟度,降低堆体含水率及缩短腐熟期,但氮素损失也显著增大(P0.01);连续式堆肥的处理效率是间歇式的2.11倍,能耗降低了52.60%。通风速率为1.95 L·min~(-1)的连续式堆肥,堆体维持高温时间最长,且最终温度稳定在较高温度47~48℃,堆末含水率最低,氮素损失处于三者的中间水平,腐熟期最短。综合分析,在通风速率为1.95 L·min~(-1)的连续运行方式下,梨形筒式反应器用于污泥稳定高效堆肥是可行的。     

复合微生物菌剂对污泥堆肥的作用效果研究

为了研究复合微生物菌剂对污泥堆肥的作用效果,以消化污泥、锯末和回流堆肥为原料,接种不同剂量(0、0.2%、0.5%)的复合微生物菌剂进行室外露天堆肥,分析了温度、含水率、pH值、全碳(TC)、全氮(TN)、种子发芽指数(germination index,GI)的动态变化,结果表明:各堆体温度保持在50℃以上的时间均超过7 d,满足堆肥卫生标准;接种复合微生物菌剂的堆体升温速率和温度最高值均大于未接种堆体,接种复合微生物菌剂有利于增加堆体水分散失量,加快堆体有机质降解速度,降低堆体氮的损失量,提高GI值;其中微生物菌剂接种量为0.5%的堆体,接种处理对水分散失、氮损失的控制和GI值的增加效果较明显.     

聚丙烯酸钠作为调理剂对好氧堆肥的保氮影响

实验以污泥、锯末、猪粪为原料,以聚丙烯酸钠(PAAS)为调理剂,利用自制好氧堆肥反应器,研究了PAAS在污泥好氧堆肥中的保氮效果。实验显示,PAAS会提高堆体的pH水平,抑制氨氮的生成,从而减少NH3的挥发源,在PAAS对水溶性氨的吸附作用下,堆肥产品的最终氨氮水平依然得到提高;PAAS对硝化反应有一定的促进作用,添加PAAS的堆体在堆肥周期内的硝氮平均增幅可达到未添加PAAS的空白堆体的4.64倍;添加PAAS的堆体在堆肥周期内全氮平均降幅只有空白堆体的52.24%。PAAS做为堆肥调理剂起到了较为明显的保氮效果。     

城市污泥与水葫芦堆肥性质变化规律

采用仓式好氧堆肥方法,研究了不同比例的城市污泥和水葫芦混合物料堆肥过程中各项评价参数(温度、含水率、pH、有机质和总氮)的变化规律。结果表明:堆肥过程中,堆体温度、含水率变化过程为先上升,再下降;堆体的pH和总氮变化过程为先降低再升高,最后趋于稳定。有机质含量在堆肥48 h内迅速下降,之后缓慢下降。对小堆体,大风量更有利于有机质的降解,但不利于氮素的保存。当m(污泥)∶m(水葫芦)为4∶1时的堆肥效果要优于m(污泥)∶m(水葫芦)为2∶1时的堆肥效果。     

分选垃圾、菜市场垃圾和腐熟污泥混合堆肥过程中氮素转化和损失研究

设计了两组高温堆肥实验,A组分选垃圾和腐熟污泥按质量比1∶1混合,B组分选垃圾、菜市场垃圾和腐熟污泥按质量比1∶1∶1混合。结果表明:A、B两组的堆体温度大于55℃的时间均不低于3d,满足卫生学要求,能够实现无害化处理,B组堆体高温持续时间比A组长近10d。堆肥过程中,A、B两组堆体TN和有机氮总体逐渐降低,氨氮先增加后减少,硝态氮则一直上升;A、B两组堆体N2O的释放主要集中在堆肥前期,堆肥前7天N_2O的释放量均达到总量的90%以上,堆肥过程中B组的氮素损失率为30.65%,低于A组的氮素损失率(48.02%)。     

污泥堆肥微生物菌剂的筛选优化及应用

从菌糠腐熟物中分离纯化12株长势良好的菌株,经16SrDNA测序分析,鉴定为链霉菌(Streptomyces sp.),将其中长势最好的一株命名为链霉菌P9。通过单因素实验及Plackett-Burman实验设计对链霉菌P9发酵培养基配方进行优化,得到培养基最佳配方为蔗糖10g/L,蛋白胨+酵母粉25.0g/L,MgSO_4·7H_2O 0.075g/L,KH_2PO_40.3g/L,K_2HPO_40.6g/L。将最佳培养基配方下制得的链霉菌P9发酵液用于污泥好氧堆肥,接种量分别为0(对照组CK)、0.5%(质量分数,下同)、1.0%、1.5%。结果表明,当接种量为0.5%时,堆体最高温度可达61.0℃,高温期维持12d,堆肥效果程度优于CK组(堆体最高温度58.1℃,高温期维持9d),接种量为1.0%、1.5%时污泥堆肥进程反而被抑制。堆肥结束时,堆体上清液的种子发芽指数均在70%以上,说明堆体物料基本腐熟无毒。可见,采用链霉菌P9发酵液作为微生物菌剂促进污泥好氧堆肥是可行的,接种量宜为0.5%。     

利用污泥熟肥作为高含水率污泥堆肥调理剂

采用静态强制通风好氧堆肥的方法,以木屑作为对比,考察了利用污泥熟肥作为调理剂对污泥堆肥过程的影响。结果表明,与以木屑作为调理剂的污泥堆体(对照组)相比,以污泥熟肥作为调理剂的污泥堆体(实验组)升温快,高温阶段(>50℃)持续时间长达10 d,满足粪便无害化卫生标准的要求,而对照组仅持续了2 d;实验组腐熟的堆肥含水率从60%降到39%,下降了21%,pH维持在7.5～8.5范围内,微生物活性较强,而对照组含水率仅下降15%,pH始终低于7.5;实验组种子发芽指数(GI)在第14天就回升到80%以上,基本上去除了植物毒性,而对照组GI在第22天才回升到50%。总体而言,污泥熟肥能显著改善堆肥中微生物的微环境,促进有机物的降解,缩短堆肥腐熟时间,是一种优质的调理剂。     

粪便与生活垃圾混合堆肥过程控制

采用强制通风静态仓进行粪便和生活垃圾混合堆肥,以玉米秸为调理剂,石灰调节pH,考察正压鼓风和负压抽吸2种通风方式对不同堆料配比堆肥过程的控制效果。试验结果表明,5种堆料配比的中层温度都达到了50℃,并保持了5 d以上,达到了堆肥无害化和稳定化的要求。正压鼓风堆料底部温度较低,负压抽吸堆料底部热量容易聚集,但是后者堆体温度分布相对均匀。负压抽吸对水分的去除效果差于正压鼓风。对于温度未达到50℃的堆料应回流处理保证无害化。粪便有机物含量高,堆肥初期易酸化,添加石灰调节pH,使堆肥顺利升温,缩短发酵期,石灰合理添加量为2%(质量分数)。采用负压抽吸的通风方式,散除堆肥初期的挥发性有机酸,再经过冷凝除臭器脱酸除臭后排放,是一种可取的方式。     

生物表面活性剂在城市污泥静态强制通风好氧堆肥中的作用

采用静态强制通风好氧堆肥模式对城市剩余污泥进行堆肥降解,并研究了生物表面活性剂鼠李糖脂对堆肥过程的作用。结果表明,堆肥过程中,添加了质量分数为0.015%鼠李糖脂溶液堆制处理和空白对照堆制处理的堆温变化都明显呈现出中温期0～5 d、高温期6～12 d和降温期13～28 d 3个阶段。实验组比空白组的堆体升温快、高温期持续时间长、堆体的含水率高。鼠李糖脂的添加,使实验组的微生物数量高于空白组。添加鼠李糖脂的堆体和空白堆体的种子发芽指数(GI)在堆肥结束时分别为53.70%和50.80%,说明鼠李糖脂促进了堆肥的腐熟,但由于相对浓缩效应,堆肥产品的重金属含量略高于空白堆体。生物表面活性剂的介入促进了堆肥中木质纤维素的初步降解。研究表明,添加鼠李糖脂能够改善堆肥处理的微环境,促进有机质降解和堆肥的腐熟。     

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos national laboratory and the doses to humans from the consumption of muscle and bone

Abstract

The purpose of this study was to determine radionuclide and trace element concentrations in bottom‐feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for ³H, ⁹⁰Sr, ¹³⁷Cs, ^totU, ²³⁸Pu, ^239,240Pu, and ²⁴¹Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of ⁹⁰Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p<0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium‐90 in fish muscle plus bone tissue significantly (p<0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E‐02 pCi g^‐1 [126E‐02 Bq kg^‐1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E‐02 pCi g^‐1 [518E‐02 Bq kg^‐1]). The differences in ⁹⁰Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (±2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 ± 0.1 mrem y^‐1 (1.0 ± 1.0 μSv y^‐1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y^‐1 (1000 μSv y^‐1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p<0.05) concentrations than in muscle of fish collected from background locations.     

Radionuclides in deer and elk from Los Alamos national laboratory and the doses to humans from the ingestion of muscle and bone

Abstract

This paper summarizes radionuclide concentrations (³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, and ^totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y^‐1 (2.2 μSv y^‐1), deer bone = 3.8 mrem y^‐1 (38 μSv y^‐1), elk muscle = 0.12 mrem y^‐1 (1.2 μSv y^‐1), and elk bone = 1.7 mrem y^‐1 (17 μSv y^‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y^‐1 (1000 μSv y^‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04.     

Leaching of seven pesticides currently used in cotton crop in Mato Grosso State—Brazil

This study aimed to evaluate the leaching of pesticides and the applicability of the Attenuation Factor (AF) Model to predict their leaching. The leaching of carbofuran, carbendazim, diuron, metolachlor, α and β endosulfan and chlorpyrifos was studied in an Oxisol using a field experiment lysimeter located in Dom Aquino – Mato Grosso. The samples of percolated water were collected by rain event and analyzed. Chemical and physical soil attributes were determined before pesticide application to the plots. The results showed that carbofuran was the pesticide that presented a higher leaching rate in the studied soil, so was the one representing the highest contamination potential. From the total carbofuran applied in the soil surface, around 6 % leached below 50 cm. The other pesticides showed lower mobility in the studied soil. The calculated values to AF were 7.06E-12 (carbendazim), 5.08E-03 (carbofuran), 3.12E-17 (diuron), 6.66E-345 (α-endosulfan), 1.47E-162 (β-endosulfan), 1.50E-06 (metolachlor), 3.51E-155 (chlorpyrifos). AF Model was useful to classify the pesticides' potential for contamination; however, that model underestimated pesticide leaching.     

Endosulfan in China 2—emissions and residues

Background, aim, and scope  Endosulfan is one of the organochlorine pesticides (OCPs) and also a candidate to be included in a group of new persistent organic pollutants (UNEP 2007). The first national endosulfan usage inventories in China with 1/4° longitude by 1/6° latitude resolution has been reported in an accompanying paper. In the second part of the paper, we compiled the gridded historical emissions and soil residues of endosulfan in China from the usage inventories. Based on the residue/emission data, gridded concentrations of endosulfan in Chinese soil and air have been calculated. These inventories will provide valuable data for the further study of endosulfan. Methods  Emission and residue of endosulfan were calculated from endosulfan usage by using a simplified gridded pesticide emission and residue model—SGPERM, which is an integrated modeling system combining mathematical model, database management system, and geographic information system. By using the emission and residue inventories, annual air and soil concentrations of endosulfan in each cell were determined. Results and discussion  Historical gridded emission and residue inventories of α- and β-endosulfan in agricultural soil in China with 1/4° longitude by 1/6° latitude resolution have been created. Total emissions were around 10,800 t, with α-endosulfan at 7,400 t and β-endosulfan at 3,400 t from 1994 to 2004. The highest residues were 140 t for α-endosulfan and 390 t for β-endosulfan, and the lowest residues were 0.7 t for α-endosulfan and 170 t for β-endosulfan in 2004 in Chinese agricultural soil where endosulfan was applied. Based on the emission and residue inventories, concentrations of α- and β-endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell. We have estimated annual averaged air concentrations and the annual minimum and maximum soil concentrations across China. The real concentrations will be different from season to season. Although our model does not consider the transport of the insecticide in the atmosphere, which could be very important in some areas during some special time, the estimated concentrations of endosulfan in Chinese air and soil derived from the endosulfan emission and residue inventories are in general consistent with the published monitoring data. Conclusions  To our knowledge, this work is the first inventory of this kind for endosulfan published on a national scale. Concentrations of the chemical in Chinese air and agricultural surface soil were calculated for each grid cell. Results show that the estimated concentrations of endosulfan in Chinese air and soil agree reasonably well with the monitoring data in general. Recommendations and perspectives  The gridded endosulfan emission/residue inventories and also the air and soil concentration inventories created in this study will be updated upon availability of new information, including usage and monitoring data. The establishment of these inventories for the OCP is important for both scientific communities and policy makers.     

Impact of spiked concentrations of Cd,Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress)

This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment.     

Butyltin compounds in sediment and fish from the Polish Coast of the Baltic Sea

Concentrations of mono- (MBT), di- (DBT), and tri-(TBT) butyltin compounds were measured in eggs, liver, and muscle of nine species of fish from four regions of the Baltic Sea - the Firth of Vistula, the Gulf of Gdańsk, Puck Bay, and the mouth of the Vistula River. The overall concentration ranges among all the fish sampled from the four sites were: < 7 to 79 ng/g for MBT, 6 to 1100 ng/g for DBT, 7 to 3600 ng/g for TBT, and 16 to 4800 ng/g for total BTs, on a wet wt basis. The highest concentration of total BTs was found in herring liver from the Firth of Vistula (4800 ng/g, wet wt) and in roach muscle from Puck Bay (3300 ng/g, wet wt), while the least concentration was found in burbot eggs and liver from the Vistula River (39 and 32 ng/g, wet wt, respectively). TBT was the major form of BTs present in most samples analyzed. Sediment samples collected from shipyards in the Gulf of Gdańsk contained butyltin concentrations ranging from 1.2 to 46 μg/g (dry wt) for MBT, 2.0 to 42 μg/g for DBT, and 2.6 to 40 μg/g for TBT. As with the fish, the majority of the BTs in sediment were present as TBT, which suggested recent exposure of the aquatic environment of the region to TBT.     

Malathion-induced sublethal toxicity on the hematology of cricket frog (Fejervarya limnocharis)

The effect of malathion [diethyl(dimethoxythiophosphorylthio)succinate] at sublethal concentration (0.006 ppm) on hematological parameters of the cricket frog (Fejervarya limnocharis) was studied for 24 hrs to 240 hrs of exposure and remarkable hematological alterations were observed. The study on hematological parameters revealed a highly significant decrease (P < 0.01) in the total erythrocytes count in malathion-exposed animals from 24 hours to 96 hrs of exposure as compared to control. Significant decreases (P < 0.01) of hemoglobin and packed cell volume were also observed from 48 hrs to 240 hrs. A significant increase (P < 0.01) in leucocytes count was noted throughout the exposure period. Elevated numbers of lymphocytes and eosinophils as found in the present study revealed lymphocytosis as well as eosinophilia, suggesting that this was a result of direct stimulation of the immunological defense due to the presence of a toxic substance or may be associated with tissue damage. The cytomorphological and cytopathological study of erythrocytes and leucocytes in malathion-exposed frogs at 0.006 ppm concentration revealed various cytotoxic effects at different exposure times. It was noted that the size and the shape of the erythrocytes were subjected to variation in different blood disorders.     

Relation between forest vegetation, atmospheric deposition and site conditions at regional and European scales

Several monitoring programs have been set up to assess effects of atmospheric deposition on forest ecosystems. The aim of the present study was to evaluate effects on the understorey vegetation, based on the first round of a regional (the Netherlands) and a European forest monitoring program. A multivariate statistical analysis showed surprisingly similar results for both data sets; the vegetation appeared to be largely determined by the ‘traditional’ factors soil, climate, and tree species, but there was a small but statistically significant effect of atmospheric deposition. The effects of deposition include a slight shift towards nitrophytic species at high N deposition in the European network, and towards acidophytic species at high S-deposition in the Dutch network. The relatively small effect of atmospheric deposition is understandable in view of the very large natural variation in environmental conditions. Time series of both vegetation and environment are needed to assess deposition effects in detail.     

Influence of crop residues on trifluralin mineralization in a silty clay loam soil

Trifluralin is typically applied onto crop residues (trash, stubble) at the soil surface, or onto the bare soil surface after the incorporation of crop residues into the soil. The objective of this study was to quantify the effect of the type and amount of crop residues in soil on trifluralin mineralization in a Wellwood silty clay loam soil. Leaves and stubble of Potato (Solanum tuberosum) (P); Canola (Brassica napus) (C), Wheat (Triticum aestivum) (W), Oats (Avena sativa), (O), and Alfalfa (Medicago sativa) (A) were added to soil microcosms at rates of 2%, 4%, 8% and 16% of the total soil weight (25 g). The type and amount of crop residues in soil had little influence on the trifluralin first-order mineralization rate constant, which ranged from 3.57E-03 day^?1 in soil with 16% A to 2.89E-02 day^?1 in soil with 8% W. The cumulative trifluralin mineralization at 113 days ranged from 1.15% in soil with 16% P to 3.21% in soil with 4% C, again demonstrating that the observed differences across the treatments are not of agronomic or environmental importance.     

Concurrent nitrate and Fe(III) reduction during anaerobic biodegradation of phenols in a sandstone aquifer

The biodegradation of phenols (5, 60, 600 mg l⁻¹) under anaerobic conditions (nitrate enriched and unamended) was studied in laboratory microcosms with sandstone material and groundwater from within an anaerobic ammonium plume in an aquifer. The aqueous phase was sampled and analyzed for phenols and selected redox sensitive parameters on a regular basis. An experiment with sandstone material from specific depth intervals from a vertical profile across the ammonium plume was also conducted. The miniature microcosms used in this experiment were sacrificed for sampling for phenols and selected redox sensitive parameters at the end of the experiment. The sandstone material was characterized with respect to oxidation and reduction potential and Fe(II) and Fe(III) speciation prior to use for all microcosms and at the end of the experiments for selected microcosms.The redox conditions in the anaerobic microcosms were mixed nitrate and Fe(III) reducing. Nitrate and Fe(III) were apparently the dominant electron acceptors at high and low nitrate concentrations, respectively. When biomass growth is taken into account, nitrate and Fe(III) reduction constituted sufficient electron acceptor capacity for the mineralization of the phenols observed to be degraded even at an initial phenols concentration of 60 mg l⁻¹ (high) in an unamended microcosm, whereas nitrate reduction alone is unlikely to have provided sufficient electron acceptor capacity for the observed degradation of the phenols in the unamended microcosm.For microcosm systems, with solid aquifer materials, dissolution of organic substances from the solid material may occur. A quantitative determination of the speciation (mineral types and quantity) of electron acceptors associated with the solids, at levels relevant for degradation of specific organic compounds in aquifers, cannot always be obtained. Hence, complete mass balances of electron acceptor consumption for specific organic compounds degradation are difficult to confine. For aquifer materials with low initial Fe(II) content, Fe(II) determinations on solids and in aqueous phase samples may provide valuable information on Fe(III) reduction. However, in microcosms with natural sediments and where electron acceptors are associated with the sediments, complete mass-balances for substrates and electron acceptors are not likely to be obtained.