造纸白泥和粉煤灰的添加对污泥消化液中氮磷回收的影响

污泥厌氧消化液中含有丰富的氮磷，若直接排放到环境中，将会对附近水体造成严重污染。由于消化液中Mg^2＋和Ca^2＋的含量很低，严重影响了氮磷的回收效果。把造纸白泥和粉煤灰引入到污泥厌氧消化液氮磷的回收当中，可以明显地提升消化液pH和提高PO4^3-P和NH3-N回收率。实验结果表明：当造纸白泥添加量为4g／（L·h）时，曝气12h后，pH可达10．19，此时PO4^3-P和NH3-N回收率分别达到64％和45％；而当粉煤灰添加量为4g／（L·h）时，曝气12h后，pH达到9．63，PO4^3-P和NH3-N回收率分别为46％和41％。但仅用曝气方式处理，12h后，pH值仅为8．52，PO4^3-P和NH3-N回收率分别只有20％和18％。实验结果还表明，水力停留时间（HRT）越大，pH上升速度越快，幅度越大，氮磷的回收效果就越好。     

磷酸铵镁法回收污泥浓缩液中氮磷的影响因素研究

以生物除磷脱氮污水处理厂污泥浓缩液为研究对象,采用正交实验方法,通过测定溶解性磷和NH4+-N的变化探索pH值、[Mg2+]/[PO34-]和[NH4+]/[PO43-]对MAP法回收氮磷效率的影响。研究表明,pH值是影响氮磷回收的一个最重要因素,当pH值达到10时,磷回收率达到最大值(81.9%),当pH值由9上升到11时,氮的去除率随pH值的升高而增加;[Mg2+]/[PO43-]和[NH4+]/[PO43-]都会影响鸟粪石(MAP)法对磷的回收率,比值越大,磷回收率越高,但当比值达到一定值后,磷回收率增长幅度趋于减缓,仅考虑磷的回收效率,[Mg2+]/[PO43-]和[NH4+]/[PO43-]的最优配比分别为1.4和6;氮去除率也受镁磷比和氮磷比的影响,当[Mg2+]/[PO43-]为1.3时,氮去除率最高,而当[NH4+]/[PO43-]为4~8时,氮去除率随着氮磷比的升高而逐渐降低。     

曝气条件对串联潜流人工湿地净污效果的影响

选取砾石、炉渣和沸石作为级配基质,构建由三级串联的潜流人工湿地模型,研究了针对三级串联的潜流人工湿地,不同曝气位置和曝气量对人工模拟污水净化效果的影响,并对两个影响因素进行二维方差分析,对曝气条件进行了优选。选取表层曝气、中层曝气、底层曝气3种曝气位置和气水体积比3∶1、6∶1、9∶1的3种曝气量。运行结果表明:曝气后,NH3-N和COD去除率上升,NH3-N去除率由7.80%最高提升到23.79%,COD去除率由5.42%最高提升至23.04%,但PO3-4-P去除率下降,由24.32%最低降至9.76%。优选的曝气位置是底层曝气,优选的气水体积比是6∶1,此时NH3-N、COD、PO3-4-P去除率分别是21.21%、23.04%、13.54%。曝气位置和曝气量的交互作用对NH3-N和COD去除率有显著影响,对PO3-4-P去除率影响不显著。     

水源水库沉积物间隙水营养盐分布特征及扩散通量

为了阐明水源水库沉积物营养盐释放对水体富营养化的贡献,以周村水库为研究对象,探讨沉积物间隙水中氮、磷营养盐的分布特征,同时采用Fick第一定律对沉积物-水界面营养盐的扩散通量进行了估算。周村水库表层沉积物间隙水中NH+4-N的浓度为6.47 to 16.82 mg·L~(-1),PO3-4-P的浓度在0.13 to 0.56 mg·L~(-1)之间,均远高于上覆水中的营养盐浓度,表明周村水库表层沉积物具有很大的营养盐释放潜能。Fick第一定律的计算结果表明,沉积物-水界面NH+4-N与PO3-4-P的扩散通量分别为62.831 to 133.231和0.364 to 1.271 mg·(m2·d)-1,研究区域中间隙水中的营养盐均由沉积物向上覆水扩散,沉积物是底层水体营养盐的重要来源。     

不同因素对人工湿地基质脱氮除磷效果的影响

在人工配制的污水中投入一定量的基质,不同条件下振荡培养,评价沸石、炉渣和陶瓷滤料3种基质在不同因素影响下对氨氮(NH4+-N)和总磷(TP)的吸附能力。结果表明,不同吸附时间时,沸石对NH4+-N的吸附效果最好,陶瓷滤料对TP的吸附效果最好;进水浓度对沸石吸附NH4+-N的影响较大,其吸附量随进水浓度的增大而增大,进水浓度对炉渣和陶瓷滤料吸附NH4+-N及炉渣吸附TP影响不大;3种基质对NH4+-N和TP的吸附量均是随吸附剂量的增加而降低,要达到较好的去污效果,应根据实验结果考虑基质投入量;pH值对沸石吸附NH4+-N影响显著,pH值6～7范围内吸附效果最好,pH值8～12的碱性条件有利于基质对TP的吸附。     

鸟粪石结晶法去除垃圾渗滤液中NH_4~+-N的效果研究

研究了鸟粪石结晶法对经混凝预处理后的垃圾渗滤液中NH4+-N的去除效果,考察了不同影响因素对NH4+-N去除效果的影响,并进行了磷酸铵镁(MgNH4PO4·6H2O,简称MAP)沉淀的表征及成分分析,并提出了反应后溶液中Mg2+、PO43-及MAP的回收利用办法。结果表明,反应的最佳条件为:pH8.5～9.5,Mg2+∶NH4+∶PO34-(摩尔比)=1.1∶1.0∶1.3,反应温度30℃,反应时间为25 min时,此时NH4+-N的去除率达94.70%;最佳沉淀剂投加组合为MgCl2.6 H2O与Na2HPO4·12H2O;pH为9.0时生成的沉淀符合典型MAP沉淀的晶体结构,生成的沉淀大部分为MAP,且没有氰化物、酚等有害物质的检出,而pH为10.5时生成的沉淀由许多疏松的微小沉淀颗粒组成,排列较杂乱,影响了沉淀的纯度。利用鸟粪石结晶法去除混凝预处理后的垃圾渗滤液中NH4+-N技术可行,经济效益合理,具有广阔的应用前景。     

藻类生物膜脱氮除磷动力学研究

将水华鱼腥藻附着固定在改性的弹性聚氯乙烯载体表面形成藻类生物膜,用于研究其脱氮除磷动力学过程。保持氮磷比约为11∶1,配制NH+4-N和PO3-4-P初始浓度变化范围分别为4.31~229.91和1.70~69.15 mg/L的模拟废水,在废水p H为6.8~7.2、室温、光照强度3 500 lx、连续光照条件下培养藻类生物膜,利用Michaelis-Menten模型测定产率系数Y、反应速率常数k与半饱和常数Km。结果显示,藻类生物膜对氮、磷的去除速率随着营养物质浓度的升高而增加;与磷相比,藻类生物膜对氮的利用效率更高。藻类生物膜脱氮除磷动力学系数分别为:1 N:Y=0.72(mg/m2chla)/(mg/L NH+4-N),k=1.24(mg/L NH+4-N)/((mg/m2chla)·d),Km=17.88 mg/L;2 P:Y=2.50(mg/m2chla)/(mg/L PO3-4-P),k=0.35(mg/L PO3-4-P)/(mg/m2chla)/d,Km=7.29 mg/L。     

青萍生长特征及其对受污染河水的修复效果

以浮萍优势品种青萍（Lemna minor）为研究对象,开展受污染河水修复。分析了青萍在不同营养盐浓度条件下的生长特征,探讨了青萍对受污染河水的修复效果。在表面积为0.0095 m2的限制空间条件下,青萍在1、2和5 mg总氮（TN）/L营养液中的生长特征都能较好地服从Logistic生长模型,受制约的临界鲜重（FW）分别为1.20、1.36和1.36 g;青萍对受污染河水中氮磷污染物具有较好的去除效果,氨氮（NH＋4-N）的平均去除率、平均去除量和平均去除速率分别为56.87%、1.22 mg/d和0.0466 mg/（g FW·h）,正磷酸盐（PO3-4-P）的平均去除率、平均去除量和平均去除速率分别为66.95%、0.25 mg/d和0.0088 mg/（g FW·h）。根据相关性分析,进水NH＋4-N和PO3-4-P浓度与其对应去除量之间极显著相关;青萍FW与NH＋4-N去除速率之间显著负相关,但与PO3-4-P去除速率之间不存在显著相关性;NH＋4-N进水浓度与去除速率相关性不显著,但PO3-4-P进水浓度与去除速率显著正相关。     

磷酸铵镁沉淀法回收尿液中N和P的实验研究

以源分离尿液为研究对象,在氨氮含量为2 850 mg N/L的微稀释尿液中,投加MgCl2.6H2O和Na2HPO4.12H2O,以磷酸铵镁沉淀法回收N和P。通过正交实验确定影响磷酸铵镁沉淀反应的因素依次为:pH值、PO34-∶NH4+、Mg2+∶NH4+、温度。在搅拌速度=100 r/min、反应温度=15℃、反应时间=10 min的条件下,实验分别考察了pH值、PO43-投加量、Mg2+投加量对磷酸铵镁沉淀法去除N、P的影响,结果表明最佳工艺条件为pH=9.5,Mg2+∶NH4+∶PO34-=1.3∶1.0∶1.0。最佳工艺条件下尿液中的NH4+-N可从2 850 mg/L降低到约125 mg/L;剩余磷酸盐浓度约7 mg/L。SEM及XRD分析表明,沉淀物的主要成分为呈斜方晶系的磷酸铵镁晶体。     

氮磷在水稻土不同发生层中的穿透性研究

为了解氮磷在不同类型水稻土发生层中的迁移特性,从浙江省宁波市和湖州市采集了27个水稻土主要发生层的原状土柱,通过饱和稳定流土柱运移试验,测定了氮和磷在不同发生层中的运移穿透曲线,用平均穿透点评估了NO-3-N、NH 4-N和PO3-4-P在各发生层中的穿透性.结果表明,氮和磷在各发生层中的穿透能力依次为:NO-3-N>NH 4-N>PO3-4-P;NO-3-N在各发生层中的穿透能力依次为:漂洗层(E层)>渗育层(P层)>表土层(A层)>腐泥层(M层)>潴育层(W层)>潜育层(G层)>犁底层(Ap层),NO-3-N的穿透能力主要与土壤饱和导水率有关,随饱和导水率增加而增强;NH 4-N穿透能力依次为:E层>P层>A层>W层>M层>Ap层>G层,NH 4-N穿透能力主要与饱和导水率和粘粒有关,迁移受粘粒明显阻滞;PO3-4-P穿透能力依次为:E层>W层>P层>M层>A层、Ap层>G层,PO3-4-P穿透能力主要受氧化铁等氧化物和粘粒的阻滞.     

Dioxin- and POP-contaminated sites—contemporary and future relevance and challenges

BACKGROUND, AIM AND SCOPE: Once they have been generated, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and other persistent organic pollutants (POPs) can persist in soils and sediments and in waste repositories for periods extending from decades to centuries. In 1994, the US EPA concluded that contaminated sites and other reservoirs are likely to become the major source of contemporary pollution problems with these substances. With this in mind, this article is the first in a new series in ESPR under the title 'Case Studies on Dioxin and POP Contaminated Sites--Contemporary and Future Relevance and Challenges', which will address this important issue. The series will document various experiences from sites contaminated with PCDD/F and other POPs. This article provides an overview of the content of the articles comprising the series. In addition, it provides a review of the subject in its own right and identifies the key issues arising from dioxin/POP-contaminated sites. Additionally, it highlights the important conclusions that can be drawn from these examples. The key aim of this article and of the series as a whole is to provide a comprehensive overview of the types of PCDD/F contaminated sites that exist as a result of historical activities. It details the various processes whereby these sites became contaminated and attempts to evaluate their contemporary relevance as sources of PCDD/Fs and other POPs. It also details the various strategies used to assess these historical legacies of contamination and the concepts developed, or which are under development, to effect their remediation. MAIN FEATURES: Special sessions on 'Contaminated sites--Cases, remediation, risk and policy' were held at the DIOXIN conferences in 2006 and 2007, and this theme will be continued at DIOXIN 2008 to be held in Birmingham. Selected cases from the approximately 70 contributions made to these sessions, together with some additional invited case studies are outlined together with the key issues they raise. By evaluating these cases and adding details of experiences published in the current literature, an overview will be given of the different features and challenges of dioxin and POP-contaminated sites. RESULTS: This article provides a systematic categorisation of types of PCDD/F and POP-contaminated sites. These are categorised according to the chemical or manufacturing process, which generated the PCDD/Fs or POPs and also includes the use and disposal aspects of the product life cycle in question. The highest historical PCDD/F and dioxin-like polychlorinated biphenyl (PCB) contamination burdens have arisen as a result of the production of chlorine and of chlorinated organic chemicals. In particular, the production of chlorinated pesticides, PCBs and the related contaminated waste streams are identified being responsible for historical releases of toxic equivalents (TEQs) at a scale of many tonnes. Along with such releases, major PCDD/F contaminated sites have been created through the application or improper disposal of contaminated pesticides, PCBs and other organochlorine chemicals, as well through the recycling of wastes and their attempted destruction. In some extreme examples, PCDD/F contaminated sites have also resulted from thermal processes such as waste incinerators, secondary metal industries or from the recycling or deposition of specific waste (e.g. electronic waste or car shredder wastes), which often contain chlorinated or brominated organic chemicals. The examples of PCDD/F and dioxin-like PCB contamination of fish in European rivers or the impact of contaminated sites upon fishing grounds and upon other food resources demonstrate the relevance of these historical problems to current and future human generations. Many of the recent food contamination problems that have emerged in Europe and elsewhere demonstrate how PCDD/F and dioxin like PCBs from historical sources can directly contaminate human and animal feedstuffs and indeed highlight their considerable contemporary relevance in this respect. Accordingly, some key experiences and lessons learnt regarding the production, use, disposal and remediation of POPs from the contaminated sites are summarised. DISCUSSION: An important criterion for evaluating the significance and risks of PCDD/Fs and other POPs at contaminated sites is their present or future potential for mobility. This, in turn, determines to a large degree their propensity for off-site transport and environmental accessibility. The detailed evaluation of contaminated site cases reveals different site-specific factors, which influence the varied pathways through which poor water-soluble POPs can be mobilised. Co-contaminants with greater water solubility are also typically present at such sites. Hence, pumping of groundwater (pump and treat) is often required in addition to attempting to physically secure a site. At an increasing number of contaminated sites, securing measures are failing after relatively short time spans compared to the time horizon, which applies to persistent organic pollutant contamination. Due to the immense costs and challenges associated with remediation of contaminated sites 'monitored natural attenuation' is increasingly gaining purchase as a conceptual remediation approach. However, these concepts may well prove limited in their practical application to contaminated sites containing persistent organic pollutants and other key pollutants like heavy metals. CONCLUSIONS: It is inevitable, therefore, that dioxin/POP-contaminated sites will remain of contemporary and future relevance. They will continue to represent an environmental issue for future generations to address. The securing and/or remediation of dioxin/POP-contaminated sites is very costly, generally in the order of tens or hundreds of millions of dollars. Secured landfills and secured production sites need to be considered as constructions not made for 'eternity' but built for a finite time scale. Accordingly, they will need to be controlled, supervised and potentially repaired/renewed. Furthermore, the leachates and groundwater impacted by these sites will require ongoing monitoring and potential further remediation. These activities result in high maintenance costs, which are accrued for decades or centuries and should, therefore, be compared to the fully sustainable option of complete remediation. The contaminated site case studies highlight that, while extensive policies and established funds for remediation exist in most of the industrialised western countries, even these relatively well-regulated and wealthy countries face significant challenges in the implementation of a remediation strategy. This highlights the fact that ultimately only the prevention of contaminated sites represents a sustainable solution for the future and that the Polluter Pays Principle needs to be applied in a comprehensive way to current problems and those which may emerge in the future. RECOMMENDATIONS AND PERSPECTIVES: With the continuing shift of industrial activities in developing and transition economies, which often have poor regulation (and weak self-regulation of industries), additional global challenges regarding POPs and other contaminated sites may be expected. In this respect, a comprehensive application of the "polluter pays principle" in these countries will also be a key to facilitate the clean-up of contaminated areas and the prevention of future contaminated sites. The threats and challenges of contaminated sites and the high costs of securing/remediating the problems highlight the need for a comprehensive approach based upon integrated pollution prevention and control. If applied to all polluting (and potentially polluting) industrial sectors around the globe, such an approach will prove to be both the cheapest and most sustainable way to underpin the development of industries in developing and transition economies.     

Sorption and Desorption Behavior of Chloroanilines and Chlorophenols on Montmorillonite and Kaolinite

The bioavailability of pollutants, pesticides and/or their degradation products in soil depends on the strength of their sorption by the different soil components, particularly by the clay minerals. This study reports the sorption-desorption behavior of the environmentally hazardous industrial pollutants and certain pesticides degradation products, 3-chloroaniline, 3,4-dichloroaniline, 2,4,6-trichloroaniline, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol on the reference clays kaolinite KGa-1 and Na-montmorillonite SWy-l. In batch studies, 2.0 g of clay were equilibrated with 100.0 mL solutions of each chemical at concentrations ranging from 10.0 to 200.0 mg/L. The uptake of the compounds was deduced from the results of HPLC-UV-Vis analysis. The lipophilic species were best retained by both clay materials. The most lipophilic chemical used in the study, 2,4,6-trichloroaniline, was also the most strongly retained, with sorption of up to 8 mg/g. In desorption experiments, which also relied on HPLC-UV-Vis technique, 2,4,6-trichloroaniline was the least desorbed from montmorillonite. However, on kaolinite all of the compounds under study were irreversibly retained. The experimental data have been modelled according to the Langmuir and Freundlich isotherms. A hypothesis is proposed concerning the sorption mechanism and potential applications of the findings in remediation strategies have been suggested.     

Persistence and dissipation kinetics of trifloxystrobin and tebuconazole in onion and soil

The persistence and dissipation kinetics of trifloxystrobin and tebuconazole on onion were studied after application of their combination formulation at a standard and double dose of 75 + 150 and 150 + 300 g a.i. ha^?1. The fungicides were extracted with acetone, cleaned-up using activated charcoal (trifloxystrobin) and neutral alumina (tebuconazole). Analysis was carried out by gas chromatograph (GC) and confirmed by gas chromatograph mass spectrometry (GC-MS). The recovery was above 80% and limit of quantification (LOQ) 0.05 mg kg^?1 for both fungicides. Initial residue deposits of trifloxystrobin were 0.68 and 1.01 mg kg^?1 and tebuconazole 0.673 and 1.95 mg kg^?1 from standard and double dose treatments, respectively. Dissipation of the fungicides followed first-order kinetics and the half life of degradation was 6–6.6 days. Matured onion bulb (and field soil) harvested after 30 days was free from fungicide residues. These findings suggest recommended safe pre-harvest interval (PHI) of 14 and 25 days for spring onion consumption after treatment of Nativo 75 WG at the standard and double doses, respectively. Matured onion bulbs at harvest were free from fungicide residues.     

Synthesis and characterization of m- and p-methylbenzyl-mercapturic acids derived from m- and p-xylenes

Chemical synthesis and physical properties of two mercapturic acids suggested as urinary metabolites of m- and p-xylenes ace described. These compounds may be used for the identification and quantivative determination by high-performance liquid chromatography of the corresponding mercapturic acids in urine.     

Levels of PCDDs and PCDFs in products and effluent from the Swedish pulp and paper industry and chloralkali process

Within the Swedish Dioxin Survey various samples from the pulp and paper industry and the chloralkali process have been analyzed by congener specific analytical methods. In addition to the generally discussed “bleaching pattern” of the tetrachlorinated congeners, these samples also contained higher chlorinated congeners like hexa-CDDs, hepta-CDFs, octa-CDD and octa-CDF. Consequently it is recommended that samples from the pulp industry should be analyzed for all PCDDs and PCDFs (tetra- through octa-). Counted as Nordic Toxic Equivalents (NTEQ), the recycled pulp samples had the highest contamination level followed by TMP, unbleached sulfite and bleached softwood and hardwood. In addition to the bleaching process, various chemicals used in the pulping, bleaching and wastewater treatment can contribute to the contamination.     

Field and laboratory studies of the fate and enantiomeric enrichment of venlafaxine and O-desmethylvenlafaxine under aerobic and anaerobic conditions

The stereoselectivity of R,S-venlafaxine and its metabolites R,S-O-desmethylvenlafaxine, N-desmethylvenlafaxine, O,N-didesmethylvenlafaxine, N,N-didesmethylvenlafaxine and tridesmethylvenlafaxine was studied in three processes: (i) anaerobic and aerobic laboratory scale tests; (ii) six wastewater treatment plants (WWTPs) operating under different conditions; and (iii) a variety of wastewater treatments including conventional activated sludge, natural attenuation along a receiving river stream and storage in operational and seasonal reservoirs. In the laboratory and field studies, the degradation of the venlafaxine yielded O-desmethylvenalfaxine as the dominant metabolite under aerobic and anaerobic conditions. Venlafaxine was almost exclusively converted to O-desmethylvenlafaxine under anaerobic conditions, but only a fraction of the drug was transformed to O-desmethylvenlafaxine under aerobic conditions. Degradation of venlafaxine involved only small stereoisomeric selectivity. In contrast, the degradation of O-desmethylvenlafaxine yielded remarkable S to R enrichment under aerobic conditions but none under anaerobic conditions. Determination of venlafaxine and its metabolites in the WWTPs agreed well with the stereoselectivity observed in the laboratory studies. Our results suggest that the levels of the drug and its metabolites and the stereoisomeric enrichment of the metabolite and its parent drug can be used for source tracking and for discrimination between domestic and nondomestic wastewater pollution. This was indeed demonstrated in the investigations carried out at the Jerusalem WWTP.     

Uptake and translocation of metformin, ciprofloxacin and narasin in forage- and crop plants

Transfer of bioactive organic compounds from soil to plants might represent animal and human health risks. Sewage sludge and manure are potential sources for bioactive compounds such as human- and veterinary drugs. In the present study, uptake of the anti-diabetic compound, metformin, the antibiotic agent ciprofloxacin and the anti-coccidial narasin in carrot (Daucuscarota ssp. sativus cvs. Napoli) and barley (Hordeumvulgare) were investigated. The pharmaceuticals were selected in order to cover various chemical properties, in addition to their presence in relevant environmental matrixes. The root concentration factors (RCF) found in the present study were higher than the corresponding leaf concentration factors (LCF) for the three test pharmaceuticals. The uptake of metformin was higher compared with ciprofloxacin and narasin for all plant compartments analyzed. Metformin was studied more explicitly with regard to uptake and translocation in meadow fescue (Festucapratense), three other carrot cultivars (D.carota ssp. sativus cvs. Amager, Rothild and Nutri Red), wheat cereal (Triticumaestivum) and turnip rape seed (Brassicacampestris). Uptake of metformin in meadow fescue was comparable with uptake in the four carrot cultivars (RCF 2-10, LCF approximately 1.5), uptake in wheat cereals were comparable with barley cereals (seed concentration factors, SCF, 0.02-0.04) while the accumulation in turnip rape seeds was as high as 1.5. All three pharmaceuticals produced negative effects on growth and development of carrots when grown in soil concentration of 6-10 mg kg⁻¹ dry weight.     

Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene

The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C₂ through C₈ organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene.     

Aerobic and anaerobic degradation of profluralin and trifluralin

Abstract

The degradation of profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐]p‐toluidine] and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was studied under aerobic and anaerobic soil conditions. Three soils (Goldsboro loamy sand, Cecil loamy sand, Drummer clay loam) were each treated with 1 ppmw herbicide; anaerobic conditions were maintained by flooding. Soil samples were extracted monthly and subjected to TLC analysis. No degradation was detected in sterile controls. Aerobic degradation of both herbicides was greatest in the Cecil loamy sand soil over the entire incubation period. Degradation of profluralin in Cecil soil under aerobic conditions was 86 percent after 4 months with three products detected; 83 percent of the trifluralin was degraded with two products detected. Anaerobic degradation accounted for 72 percent of the profluralin and 78 percent of the trifluralin after 4 months. Degradation of both herbicides increased with incubation time for the first 3 months and decreased slightly thereafter. Generally there was more extensive degradation (percent and in number of products formed) of profluralin than trifluralin under the conditions tested. More degradation products were detected for both herbicides under aerobic conditions than under anaerobic conditions.     

Sources and distribution of polychlorinated-dibenzo-p-dioxins and -dibenzofurans in soil and sediment from the Yellow Sea region of China and Korea

Polychlorinated-dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs) were measured in soils and sediments from the Yellow Sea region. Korean soils and sediments mostly contained detectable PCDD/Fs and showed a widespread distribution among locations. Soil and sedimentary PCDD/Fs from China were comparable to or less than those in Korea. The patterns of relative concentrations of individual congeners in soils were different between the two countries, but similar in sediments. Sources of PCDD/Fs in China and Korea were found to be independent of each other and their distributions reflected matrix-dependent accumulation. Spatial distribution indicated some point sources in Korea while Chinese sources were more widespread and diffuse. PCDD/Fs measured in the coastal areas of the Yellow Sea were comparable to or less than those previously reported in for eastern Asia. However, ∑TEQs in soils and sediments were near to or, in some cases exceeded environmental quality guidelines.