Peat soils as a source of lead contamination to upland fluvial systems

Upland peat soils are generally regarded as effective sinks of atmospherically deposited lead. However, the physical process of erosion has the potential to transform peat soils from sinks to sources of lead contamination. Lead input and fluvial lead outputs (dissolved+particulate) were estimated for a contaminated and severely eroding peatland catchment in the southern Pennines, UK. Lead input to the catchment is 30.0+/-6.0gha(-1)a(-1) and the output from the catchment is 317+/-22.4gha(-1)a(-1). Suspended particulate matter accounts for 85% of lead export. Contaminated peat soils of the catchment are a significant source of lead to the fluvial system. This study has demonstrated strong coupling between the physical process of erosion and the mobilization of lead into the fluvial system. The process of peat erosion should therefore be considered when estimating lead outputs from peatland catchments, especially in the context of climate change.     

Chemical fractionation of copper, lead and zinc in ombrotrophic peat

Measurement of operationally defined chemical fractions in ombrotrophic peat samples provides information not obtained by total metal extractions. Examination of such sequential data permits interpretation of process dynamics. Results for copper, lead and zinc chemical fractionation of peat profiles from Ringinglow Bog, near Sheffield, Great Britain, are reported and discussed. Lead and zinc share similar patterns of partitioning. A considerable proportion of these records is in a form predisposed to transformation and mobilisation. In contrast, much of the copper is comparatively immobile, it being associated with the more chemically intractable fractions. The results suggest that peat copper deposition records may be used for reconstruction of pollution history. The use of lead and zinc records for these purposes is problematic.     

泥炭作为吸油材料的试验

为了研制一种理想的吸油剂,对泥炭、秸秆、锯末和改性泥炭用作吸油材料进行了对比试验.结果表明,未改性的风干泥炭吸油效果好于秸秆和锯末,而且是藓类泥炭吸油效果好于草本泥炭;对于同一类型的泥炭,中细纤维结构的吸油量高于中粗纤维结构的;与未改性的风干泥炭相比,不论采用物理方法还是物理化学方法进行改性,改性后泥炭的吸油效果均好于改性前的.试验证明了泥炭可以作为一种吸油材料,尤其是改性后的泥炭更是一种效率高、成本低、环保型的吸油材料.     

几种腐殖填料生物滤池COD去除效能比较研究

分别采用腐殖垃圾、泥炭、煤炭等腐殖填料及河沙构筑生物滤池,处理模拟废水,比较研究其COD去除效能及降解特征,为工艺填料改性提供理论依据。几种填料的扫描电镜分析图显示腐殖垃圾及泥炭以团聚体三维空间结构为主;煤炭与河沙表面粗糙程度较小,且主要由颗粒状物质构成。稀释平板涂布法分离出各生物滤池中发挥主要作用的微生物共3种,各系统菌落数量有差异,但种类相同。3种腐殖填料生物滤池在进水有机物浓度为500 mg/L及1000 mg/L时均有较理想的有机物去除效率。3种腐殖填料生物滤池中泥炭构筑的腐殖填料生物滤池有机物比降解速率最小,因而微生物比增长速率最小,微生物增长和自身氧化最易趋向于动态平衡,对应的饱和水力渗透系数最大,滤池最不易发生堵塞,最有利于腐殖填料生物滤池长期稳定运行,证明泥炭是一种优良的生物介质。     

Kinetics of peat soil dissolved organic carbon release to surface water. Part 2. A chemodynamic process model

Temporary water reservoirs built upon peat soil may exhibit water quality impairment from elevated dissolved organic carbon (DOC). Microbiological decay of the organic carbon in the bed with subsequent release produces "tea" colored water which may require treatment prior to use. This paper contains a process-based mathematical model that quantifies the DOC release from the bed and its build-up in the water column. The model elements are based on microbial DOC production rates and bed sediment transport kinetics describing its' release from the organic soil systems. It relies on laboratory data obtained from an experimental study, Part 1, designed to simulate the DOC chemodynamics of aquatic reservoirs built upon peat soils. A two-step DOC release process was structured based on the experimental findings. The model mechanism assumes a quick release fraction that characterizes the upper soil surface layers as a "tea bag" type release process. This is followed by a fraction that is continuously produced and then released at a constant rate overtime by on-going microbial processes within the upper soil layers. The depth of the active layer, selected as h* = 0.3 cm, is the single adjustable parameter in the model. Concentration predictions of the are consistent with the laboratory simulations and field observations. Measured vs. model-calculated DOC concentrations for both in the microcosm bed and water column are used to test critical features of the proposed model. As conceived and structured it appears to be a realistic first step in quantifying the DOC release consequences for the water column of a reservoir sited upon a peat-soil bed. The development ends with an application to a hypothetical reservoir in order to illustrate model strengths and uncertainties.     

The migration of uranium into peat-rich soils at Broubster, Caithness, Scotland, U.K.

Uranium is being actively transported from uraniferous sedimentary rocks into a peat bog at the Broubster natural analogue site in Caithness, Scotland. Massive calcareous sandstone within the Caithness Flags sequence is the main source of uranium which resides primarily within diagenetic apatite and dispersed U---Si---Ti phases. Supergene weathering processes have decalcified the sandstone and are effective in mobilising uranium by groundwater leaching, primarily along a fault zone. Uranium transport in solution by means of groundwater and surface flows is effectively terminated by retardation within 4-kyr-old peat deposits laid down on boulder clay. This process of secondary fixation has resulted in a young uranium anomaly in the peat which comprises in excess of 0.1 wt% U. The site has been investigated comprehensively to define the geometry of the anomaly together with the hydrogeology, hydrochemistry, petrology, mineralogy and the nature of the peat sink-term. The main physical and geochemical properties of the system, including the uranium decay series radionuclide distributions in water and solid samples, are documented in this paper. From these data, the processes governing the distribution of uranium have been quantified using a three-dimensional groundwater flow package and an equilibrium speciation model incorporating a recently developed electrostatic surface complexation model to account for cation-organic interactions. The results described form part of a coordinated project on natural radionuclide migration undertaken to improve confidence in predictive methods used for radiological assessment.     

Utilisation of chemically stabilized arsenic-contaminated soil in a landfill cover

The aim of the study was to determine if an As-contaminated soil, stabilized using zerovalent iron (Fe⁰) and its combination with gypsum waste, coal fly ash, peat, or sewage sludge, could be used as a construction material at the top layer of the landfill cover. A reproduction of 2 m thick protection/vegetation layer of a landfill cover using a column setup was used to determine the ability of the amendments to reduce As solubility and stimulate soil functionality along the soil profile. Soil amendment with Fe⁰ was highly efficient in reducing As in soil porewater reaching 99 % reduction, but only at the soil surface. In the deeper soil layers (below 0.5 m), the Fe treatment had a reverse effect, As solubility increased dramatically exceeding that of the untreated soil or any other treatment by one to two orders of magnitude. A slight bioluminescence inhibition of Vibrio fischeri was detected in the Fe⁰ treatment. Soil amendment with iron and peat showed no toxicity to bacteria and was the most efficient in reducing dissolved As in soil porewater throughout the 2 m soil profile followed by iron and gypsum treatment, most likely resulting from a low soil density and a good air diffusion to the soil. The least suitable combination of soil amendments for As immobilization was a mixture of iron with coal fly ash. An increase in all measured enzyme activities was observed in all treatments, particularly those receiving organic matter. For As to be stable in soil, a combination of amendments that can keep the soil porous and ensure the air diffusion through the entire soil layer of the landfill cover is required.     

泥炭对甲苯的吸附-解吸行为研究

用热处理方法对泥炭进行活化改性,探讨了对甲苯的吸附性能及影响因素,并研究了甲苯在泥炭上的吸附/解吸行为。结果表明,粒径在0.6～1 mm之间的泥炭在160℃热处理5 h,在pH为7的条件下对甲苯有良好的吸附效果,对甲苯的吸附量为0.32 mg/g。泥炭对甲苯的吸附在20 min内基本达到平衡,可用二级吸附速率方程进行拟合。甲苯在泥炭上的吸附和解吸均呈现明显的非线性,用Langmuir模型能较好地描述,泥炭对甲苯的饱和吸附量为0.939 mg/g。甲苯在泥炭上的平均解吸率为6.393%,并且出现了滞后现象,表明苯系物与泥炭有较强的结合能力。研究结果为应用泥炭作为PRB装填介质进行原位修复甲苯污染的地下水提供了理论依据。     

In situ fluidization for peat bed rupture,and preliminary economic analysis

This study concerns in situ fluidization (ISF), a new remediation method with potential application to the remediation of NAPL and heavy metal contaminants, by their release from the fluidized zone generated by a water jet. The present study examines the effect of ISF on layers of peat, of significance owing to its role as an important NAPL and metal contaminant trap. Once trapped, such contaminants are not readily accessible by most remedial methods, due to the low permeability and diffusivity of the peat. A simple tank experiment is used to demonstrate rupture of a peat layer by ISF, with removal of the peat as elutriated fines and segregated peat chunks. The application of ISF in the field is then examined by three field trials in uncontaminated sands, in both saturated and unsaturated conditions. Fluidized depths of up to 1.9 m in the saturated zone (with refusal on a peat layer) and 2.5 m in the unsaturated zone (no refusal) were attained, using a 1.9-m-long, 50 mm diameter jet operated at 5-13 1 s(-1). Pulses of dark turbidity and shell fragments in the effluent indicated the rupture of peat and shelly layers. The experiments demonstrate the hydraulic viability of ISF in the field, and its ability to remove peat-based contaminants. The issues of appropriate jet design and water generation during ISF are discussed, followed by a preliminary economic analysis of ISF relative to existing remediation methods.     

Transport of lead and diesel fuel through a peat soil near Juneau, AK: a pilot study

A set of peat column experiments was used to determine the transport potential of lead (Pb) and diesel range organics (DRO) in palustrine slope wetlands near Juneau, AK. This project is important to southeast Alaskan communities because limited land resources are forcing development of regional wetlands. This study was instigated by concerns that proposed modifications to a nearby rifle range using DRO-contaminated soil posed a potential risk to an anadromous fish-bearing stream 250 m from the site. Three pairs of peat columns were extracted from the rifle range for analysis, one pair along and two pairs across the natural bedding planes of the soil. One column in each pair was spiked with Pb and DRO and the other was used as a control. Approximately 1-year worth of water (171 cm) was passed through each column and leachate was collected at regular intervals. The results showed that substantial DRO transport only occurred along the bedding planes. Leads was surprisingly mobile, both along and across the bedding planes with estimated soil-water partition coefficients several orders of magnitude lower than commonly published values, probably because the peat was heavily Pb-loaded by lead from bullets and because the peat's acidic, organic-rich environment enhanced Pb mobility. The chemical outflow behavior agreed with a simple macropore transport model. These results underscore the need for caution when developing regional wetlands.     

Practical and mechanistic aspects of the removal of cadmium from aqueous systems using peat

A sphagnum peat moss removed Cd from aqueous solutions very efficiently, and its effectiveness in taking up the metal was significantly enhanced by exposure to a 1N NaOH solution. The capacity of the untreated peat for Cd reached 300 g/kg and that of the NaOH-activated peat was over 400 g/kg. Although saturation was rarely reached, the Cd uptake from concentrated solutions often exceeded 200 g/kg. In column experiments, 1g of the NaOH-activated peat completely removed the metal from over 0.2L of a 200-mg/L Cd solution (final Cd concentration<0.1mg/L), while 1g of non-activated peat cleared Cd from less than 25% of that volume. The cation exchange capacity measured for the peat depended on the time of contact with the exchanging solution. After 72 h contact, the value for the NaOH-activated peat was 135 cmol(c)/kg. In addition to uptake by exchange, a significant amount of Cd was sorbed by non-exchange mechanisms. FTIR spectroscopy revealed the importance of carboxyl groups in the uptake.     

Development of a biobarrier for the remediation of PCE-contaminated aquifer

The industrial solvent tetrachloroethylene (PCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to develop a biobarrier system, which includes a peat layer to enhance the anaerobic reductive dechlorination of PCE in situ. Peat was used to supply primary substrate (electron donor) continuously. A laboratory-scale column experiment was conducted to evaluate the feasibility of this proposed system or PCE removal. This experiment was performed using a series of continuous-flow glass columns including a soil column, a peat column, followed by two consecutive soil columns. Anaerobic acclimated sludges were inoculated in all three soil columns to provide microbial consortia for PCE biodegradation. Simulated PCE-contaminated groundwater with a flow rate of 0.25 l/day was pumped into this system. Effluent samples from each column were analyzed for PCE and its degradation byproducts (trichloroethylene (TCE), cis-dichloroethylene (cis-DCE), vinyl chloride (VC), ethylene (ETH), and ethane). Results show that the decrease in PCE concentrations and production of PCE byproducts were observed over a 65-day operating period. Up to 98% of PCE removal efficiency was obtained in this passive system. Results indicate that the continuously released organics from peat column enhanced PCE biotransformation. Thus, the developed biobarrier treatment scheme has the potential to be developed into a cost-effective in situ PCE-remediation technology, and can be utilized as an interim step to aid in system scale-up.     

Leaching of mercury from peat soil

The factors influencing the sorption and leaching of mercury in peat soil were studied using small additions of labelled mercury in peat lysimeters. Additions of chloride, fertilizer or sterilant did not affect the leaching of mercury. Complete drying of the peat improved the leaching of mercury probably because of changes in the physical properties of the peat soil.     

Leaching kinetics of water soluble organic carbon (WSOC) from upland soil.

The kinetics of the leaching process of Water Soluble Organic Carbon (WSOC) from an upland soil were studied in a column leaching experiment. The pattern of the leaching curve indicated multiphasic release kinetics. A conceptual model was proposed to divide capillary and gravitational pores. The translocation of organic carbon in soil during leaching occurs in four sequential steps. 1) degradation of insoluble organic carbon to form WSOC; 2) desorption into capillary pore water; 3) diffusion towards gravitation pore water; and 4) leaching by convection flow. The overall kinetics of the leaching process can be depicted using an equation with three additive terms for degradation, desorption/diffusion, and convection, respectively.     

Peatlands: a major sink of naturally formed organic chlorine

It is a little known fact that many chlorinated organic compounds occur naturally and that some are also indispensable to life on earth. Here, we show that chlorination of organic compounds during humification processes in peat is widespread in nature. Globally this process has led to the accumulation of approximately 280-1000 million tons of organically bound chlorine in peatlands during the postglacial period.     

Chemical and ecological effects of a pennine peat-slide

A peat landslide which occurred in Upper Teesdale in 1983 is described. The slide followed thunderstorm rainfall of a very rare intensity (104.8 mm in 2.5 h) and a long predicted return period (2500 years). A large mass of peat (30,000 tonnes wet weight) entered the headwaters of the River Tees, resulting in chemical changes such as increases in suspended solids, iron, aluminium and lead in the river, and a consequent fish kill. The probable cause of the fish kill was the high suspended solid content (particularly peat and iron hydroxide) of the flood water. Effects on the invertebrate fauna of the River Tees are also considered.     

泥炭树脂颗粒对水溶液中十二烷基苯磺酸钠的去除

泥炭树脂颗粒对水溶液中十二烷基苯磺酸钠 (SDBS)具有很好的去除效果。数据分析表明 ,Freundlich和 Langmuir吸附等温方程可以很好地描述这一过程。通过 L angmuir方程计算出颗粒对 SDBS的最大吸附量为 3 3 .3 3 mg·g- 1。在试验条件下 ,吸附量随着 SDBS的初始浓度增加而增加 ,当溶液的初始 p H在 4～ 8的范围时 ,颗粒对 SDBS吸附量变化很小。溶液的初始浓度对吸附速率产生明显影响 ,浓度越低吸附速率越快 ,达到吸附平衡所需的时间越短。准二级动力学模型能够很好地描述颗粒对 SDBS的吸附过程。     

Storage and distribution of trace metals and spheroidal carbonaceous particles (SCPs) from atmospheric deposition in the catchment peats of Lochnagar, Scotland.

Lochnagar is a remote mountain lake to the south-east of the Cairngorm region in Scotland. Its catchment receives anthropogenic trace metals solely from atmospheric deposition. Ten peat cores were taken from the catchment and analysis confirmed that they have been contaminated by trace metals. The peats have an high affinity for trace metals and this results in metal accumulation in the surface peat layers. The formation of trace metal sulphides may also reduce remobilisation. In this way, trace metals derived from atmospheric deposition have been scavenged and accumulated. In contaminated peat layers, 77.4% Hg, 89.6% Pb, 93.4% Cu, 72.4% Zn and 86.5% Cd of the total stored are from anthropogenic sources. The accumulated trace metals in the peats can potentially influence the lake system through erosion. Spheroidal carbonaceous particle (SCP) profiles were used to date the peat cores. By referring to the SCP profiles in the peats and comparing these with the trace metal profiles in the lake sediments, the mobility of trace metals in the catchment peats is confirmed.     

Dynamics of copper and tetracyclines during composting of water hyacinth biomass amended with peat or pig manure

Composting is one of the post-treatment methods for phytoremediation plants. Due to a high potential of water hyacinth to accumulate pollutants, the physicochemical parameters, microbial activity as well as fates of copper (Cu) and tetracyclines (TCs) were investigated for the different amended water hyacinth biomass harvested from intensive livestock and poultry wastewater, including unamended water hyacinth (W), water hyacinth amended with peat (WP), and water hyacinth amended with pig manure (WPM) during the composting process. Pig manure application accelerated the composting process as evidenced by an increase of temperature, electrical conductivity (EC), NH₄-N, as well as functional diversity of microbial communities compared to W and WP treatments. Composting process was slowed down by high Cu, but not by TCs. The addition of peat significantly increased the residual fraction of Cu, while pig manure addition increased available Cu concentration in the final compost. Cu could be effectively transformed into low available (oxidizable) and residual fractions after fermentation. In contrast, less than 0.5% of initial concentrations of TCs were determined at the end of 60-day composting for all treatments in the final composts. The dissipation of TCs was accelerated by the high Cu concentration during composting. Therefore, composting is an effective method for the post-treatment and resource utilization of phytoremediation plants containing Cu and/or TCs.     

Distribution and speciation of mercury in the peat bog of Xiaoxing'an Mountain,northeastern China

Most reports on mercury (Hg) in boreal ecosystems are from the Nordic countries and North America. Comparatively little information is available on Hg in wetlands in China. We present here a study on Hg in the Tangwang River forested catchment of the Xiaoxing'an Mountain in the northeast of China. The average total Hg (THg) in peat profile ranged from 65.8 to 186.6 ng g(-1) dry wt with the highest at the depth of 5-10 cm. THg in the peat surface was higher than the background in Heilongjiang province, the Florida Everglades, and Birkeness in Sweden. MethylHg (MeHg) concentration ranged from 0.16 to 1.86 ng g(-1) dry wt, with the highest amount at 10-15 cm depth. MeHg content was 0.2-1.2% of THg. THg and MeHg all decreased with the depth. THg in upland layer of soil (0-20 cm) was comparable to the peat surface, but in deeper layers THg concentration in peat was much higher than that in the forested mineral soil. THg in the peat bog increased, but MeHg decreased after it was drained. THg content in plant was different; THg contents in moss (119 ng g(-1) dry wt, n=12) were much higher than in the herbage, the arbor, and the shrubs. The peat bog has mainly been contaminated by Hg deposition from the atmosphere.