Tolerance of calluna vulgaris and peatland plant communities to sulphuric acid deposition

Critical loads offer a unique way of evaluating impacts of acid deposition by quantifying environmental sensitivity. The critical loads of acidity for UK peat soils have been based upon an arbitrary reduction in pH of 0.2 units. This chemical shift needs to be better related to adverse effects on sensitive biological receptors. It is known that effective precipitation pH equates closely to soil solution pH, and the latter is directly linkable to biotic effects of pH change. On continuation of a long-term experiment assessing impacts of simulated acid rain on peat microcosms in a realistic outdoor environment, Calluna vulgaris continued to flourish at acid deposition loads well above the existing critical load. Calluna plants were harvested and analysed, and acid deposition treatments to the microcosms continued to allow natural vegetation to regenerate. A diverse mixture of moorland plants and bryophytes established at acidity treatments well above the existing critical load, and only a very high acid load resulted in no natural regeneration. A critical effective rain pH value of 3.6 is suggested as a basis for setting critical loads. At this pH, Calluna grows well, and a healthy diverse vegetation community re-establishes when harvested. It is suggested that the peat critical load should be set at the acid load that, at any specific site, would result in a mean effective precipitation pH of 3.6.     

The impact of enhanced ammonium sulphate inputs exceeding critical load on calluna vulgaris /peat soil microcosms

Ammonium sulphate at six concentrations in simulated precipitation has been applied weekly over two years to Calluna vulgaris growing in peat soil. The nitrogen deposition treatments were chosen to embrace and exceed critical load. The growth and composition of the Calluna and the changes over time in the chemistry of the peat soil and its soil solution were monitored. In spite of significant increases in foliar nitrogen concentration in new shoots, especially in the first year, growth did not increase significantly in response to nitrogen treatment. Several factors could be contributing to the lack of significant growth response. (1) Increasing ammonium input significantly acidified the soil solution, which could adversely effect growth directly. (2) Foliar calcium concentration was reduced significantly in both years by the ammonium sulphate treatments, and more calcium was undoubtedly lost from the rooting zone at higher nitrogen inputs. (3) Foliar phosphate declined significantly between the first and second year, so lack of growth response might also reflect a phosphorus limitation. There was a distinctly visible darkening of the leaves in response to increasing ammonium applications, especially for the first year's growth, and the chlorophyll a and b concentrations in leaves from new growth at the three highest nitrogen treatments were significantly (at P <0.05) higher than those for the control. The pigment concentrations fell markedly by the end of the second season, and treatment effects were much less consistent. It is suggested that pigment analysis therefore probably has little diagnostic value for assessing damage from pollutant nitrogen effects.     

The role of humic substances in chromium sorption onto natural organic matter (peat)

To elucidate mechanisms of Cr³⁺ sorption onto the unaltered solid natural organic matter, the comparative studies of this ion binding from a solution at pH 4.0 onto three selected particle size fractions: 2000–1000 μm, 630–200 μm and 63–20 μm of markedly different HS content and structure, separated by a wet sieving from an overall sample of peat (Brushwood Peat Humus) were carried out. Comparable patterns of COOH groups and CEC_t confirmed that for cation exchange capacity were responsible mainly cations connected with COO⁻ functional groups. It was though found that aliphatic acids in the solid state did not take part in Cr³⁺ binding, thus the finest studied fraction 63–20 μm of the highest contents of functional groups showed the lowest sorption capacity for Cr³⁺, while similar patterns of sorbed Cr³⁺, soluble HS content and base CEC₀ indicated that these parameters were directly interrelated. The base ion exchange processes determined by CEC₀ (with Ca²⁺ as a predominant exchangeable cation) appeared to be not the major mechanisms responsible for Cr³⁺ sorption. For this metal, strong binding to insoluble large molecular weight organic pool two- to threefold prevailed over the ion exchange processes. Very low acid desorption indicated generally low mobility of Cr³⁺-organic compounds.     

Natural bitumens versus oil pollution in the Vlasina lake peat

Free and associated bitumens were isolated by sequential extraction from Vlasina lake peat (SE Serbia) and were investigated in order to differentiate between oil pollution and natural bitumens. Four peat samples were collected at different depths, on a peat island. Gas chromatographic (GC) and gas chromatography/mass spectrometry (GC/MS) analysis revealed the presence of three markedly different bitumen fractions. Here we show that the free bitumens are representing the native peat bitumens. The two associated bitumens are mainly the products of bacterial rework of organic substance, which were then trapped by two differing mechanisms. The bitumens characteristics and association features exclude a contribution of oil pollution.Selected article from the Regional Symposium on Chemistry and Environment Krusevac, Serbia, June 2003, organised by Dr. Branimir Jovancicevic.     

泥炭净化含油污水的研究

泥炭比重小、质量轻，富含有机质，是一种吸附能力很强的吸油材料。本文通过大量试验论述了泥炭净化含油污水的实验条件和方法。结果表明。泥炭经热加工处理后，由原来的亲水性变成疏水性，在含油污水中实现吸油而不吸水；采用不同的净化方式效果不同，静态方式泥炭可吸附其自身重量的５－１０倍的油，动态吸油高达１０倍以上；藓类泥炭、草木泥炭及木本泥炭对油的吸附效果也不同，分别可吸附油６—９．５Ｌ／Ｋｇ、４—８Ｌ－／Ｋｇ和１—２．５Ｌ／Ｌｇ。     

Evaluating peats for their capacities to remove odorous compounds from liquid swine manure using headspace “solid‐phase microextraction”

Abstract

This paper reports on research designed to investigate the capacities of different highly characterized peats to remove odorous compounds from liquid swine manure (LSM). Peat types representing a wide range of properties were tested in order to establish which chemical and physical properties might be most indicative of their capacities to remediate odors produced by LSM. Eight percent slurries (of peat/LSM) were measured for odor changes after 24 hours using odor panel and GC/MS‐Solid‐phase microextraction (GC/MS‐SPME) analysis.

The GC/MS‐SPME and odor panel results indicated that, although all peats tested in this study were found to be effective at removing odor‐causing compounds found in LSM, some peats tended to work better than others. Overall, the peats that were the most effective at removing odor‐causing compounds tended to have lower bulk densities, ash contents, fulvic acids contents, and guaiacyl lignins contents,and higher water holding capacities, hydraulic conductivities, “total other lignins”; contents, hydrogen contents, carbon contents, and total cellulose contents.

GC/MS‐SPME analysis was found to be a reasonably inexpensive and efficient way of conducting this type of research. It allows one to identify a large number of the odor‐causing compounds found in LSM, and more importantly, to detect with some precision specific differences in the amounts of these compounds between peat types.     

Ecological assessment of natural resources in agroecosystems of Dutch Lowland Peat area

In ecological assessment many abiotic and biotic indicators, reflecting the many facets of ecosystems, are used. Reporting on the state of the environment requires that information on separate indicators be integrated into comprehensive yardsticks or indices. In this paper we describe a method for assessing the quality of natural resources in agroecosystems and present a case study on the Dutch Lowland Peat area. Using a coherent set of physical, chemical, and biotic indicators, we compare the present situation with the long-term policy objective of strategic policy plans. Results are depicted in a radial plot. The present ecological quality of the Lowland Peat area has been found to deviate strongly from that of the desired state.     

Exploratory study of suspended sediment concentrations downstream of harvested peat bogs

Peat bog harvesting is an important industry in many countries, including Canada. To harvest peat, bogs are drained and drainage water is evacuated towards neighboring rivers, estuaries or coastal waters. High suspended sediment concentrations (SSC) were found in the drainage water at one particular site during the 2001–2002 spring seasons in New Brunswick (Canada). The main objective of this study was to verify this observation at other sites, compare SSC levels leaving harvested peat bogs with those leaving an unharvested bog, and to determine if high SSC events happen only in Spring or all year round. Suspended sediment concentrations were monitored downstream of three harvested peat bogs and an unharvested reference bog located in New Brunswick during the ice free seasons of 2003–2004. On average, SSC at the harvested sites exceeded 25 mg/l, which is the recommended daily maximum concentration, 72% of the time, while the same concentration was exceeded 30% of the time at the unharvested sites. SSC were found to be significantly higher at harvested sites than at the reference sites for all seasons. The highest SSC medians were recorded in the Fall but SSC was elevated in all seasons. High SSC levels in receiving waters may be caused by field ditching activities and insufficient sediment controls. Findings suggest the NB Peat Harvesting 25 mg/l SSC guideline should be reviewed.     

Metal sorption by peat and algae treated peat: kinetics and factors affecting the process

The article presents a new approach that can be used for the purification of water contaminated by heavy metals. The treatment of peat with microalgae showed to be an effective way of increasing metal uptake by peat. Metal sorption was studied for a multimetal solution containing Cu, Cd, Ni, Zn, Cd, and Pb. Cu and Pb were found to be the metals having the highest affinity to peat. Water hardness has a strong effect on the uptake of borderline metals (Cd, Ni, Zn, Cd) from a solution. The use of algae for peat treatment resulted in less time to reach an equilibrium (24 h vs. 72 h for pure peat), and the effect of water hardness (Ca²⁺) on metal uptake was considerably reduced. Both peat and algal-treated peat were able to take up metals from rather acidic solutions (pH 3.0). pH had less influence on the metal uptake compared with water hardness. The affinity of heavy metals to peat was the following: Pb > Cu > Ni > Cd > Zn > Co. It slightly changed to Pb > Cu > Ni > Cd ≈ Co ≈ Zn when the combined sorbent, peat treated with microalga, was applied.     

Improved VOC bioremediation using a fluidized bed peat bioreactor

A gas–solid fluidized bed bioreactor was successfully used to treat air contaminated with a volatile organic compound (VOC). A bioreactor containing both a fluidized and packed bed of moist peat granules removed ethanol, a representative VOC, from an air stream. The fluidized bed operation mode of the bioreactor outperformed the packed bed mode. The maximum elimination capacity (EC) of ethanol in the fluidized mode was 1520 g m⁻³ h⁻¹, with removal efficiencies ranging between 45 and 100%, at loadings up to 3400 g m⁻³ h⁻¹. Maximum EC was 530 g m⁻³ h⁻¹ in the packed bed mode. Removal efficiency in the fluidized bioreactor was best at the lowest velocity, where the bubbling bed fluidization regime predominated. As gas velocity increased, the size and amount of large bubbles (slugs) increased and removal efficiency decreased while elimination capacity increased.