Methane emissions from forested closed landfill sites: Variations between tree species and landfill management practices.

Trees in natural and managed environments can act as conduits for the transportation of methane (CH4) from below ground to the atmosphere, bypassing oxidation in aerobic surface soils. Tree stem emissions from landfill sites exhibit large temporal and spatial variability in temperate environments and can account for approximately 40% of the total surface CH4 flux. Emission variability was further investigated in this study by measuring CH4 and CO2 fluxes from landfill sites with different management strategies and varying tree species over a 7-month period. Stem and soil measurements were obtained using flux chambers and an off-axis integrated cavity output spectroscopy analyser. Analysis showed average stem and soil CH4 emissions varied significantly (p < 0.01) between landfills with different management practices. On average, tree stem CH4 fluxes from sites with no clay cap but gas extraction, clay cap and gas extraction, and no clay cap and no gas extraction were 1.4 ± 0.4 µg m-2 h-1, 47.2 ± 19.0 µg m-2 h-1, and 111.9 ± 165.1 µg m-2 h-1, respectively. There was no difference in stem CH4 fluxes between species at each site, suggesting environmental conditions (waterlogging) and site age had a greater influence on both stem and soil fluxes. These results highlight the importance of management practices, and the resultant environmental conditions, in determining CH4 emissions from historic landfill sites.

The use of chemical composition data in waste management planning--a case study.

As the waste industry continues to move from a disposal-based system to one based on a combination of recovery options, the need for information on the composition of waste increases and this is reflected by the amount of information on the physical composition of municipal solid wastes that is now available. However, there is far less information on the chemical composition of municipal solid waste. The results from a number of chemical surveys from Europe are compared and show a reasonable degree of agreement, but several problems were identified with the data. Chemical and physical compositional data are combined in a case study example to investigate the flow of key potential pollutants in an integrated solid waste management system that uses materials recycling, composting, incineration and landfilling. This case study has shown that an integrated waste management strategy diverts lead and cadmium away from composting and recycling to incineration, which effectively isolates these elements from the environment through efficient capture of the pollutants followed by secure landfilling or recycling of the residues. However, further work is needed to determine the distribution of mercury in incineration residues and its fate when the residues are landfilled.

The analysis of flue gas treatment residues using non-destructive X-ray fluorescence as a regulatory compliance test.

Current and proposed European Union (EU) regulations require the residual material from municipal solid waste incineration to be characterised prior to disposal. X-Ray fluorescence (XRF) provides a rapid and non-destructive technique for analysing such materials.

Randomized study comparing the effects of hydroxyethyl starch solution with Gelofusine on pulmonary function in patients undergoing abdominal aortic aneurysm surgery.

BACKGROUND: Restoring blood flow to ischaemic tissue can cause lung damage with pulmonary oedema. Hydroxyethyl starch (HES) solution, when used for volume replacement, may modify and reduce the degree of ischaemia-reperfusion injury. We compared the effects of HES solution with those of Gelofusine solution on pulmonary function, microvascular permeability and neutrophil activation in patients undergoing elective infrarenal abdominal aortic aneurysm surgery. METHODS: Forty patients were randomized into two groups. The anaesthetic technique was standardized. Lung function was assessed with the PO(2)/FI(O(2)) ratio, respiratory compliance, chest x-ray and a score for lung injury. Microvascular permeability was determined by measuring microalbuminuria. Neutrophil activation was determined by measurement of plasma elastase. RESULTS: Four hours after surgery, the median (quartile values) PO(2)/FI(O(2)) ratio was 40.3 (37.8, 53.1) kPa for the HES-treated patients compared with 33.9 (31.2, 40.9) kPa for the Gelofusine-treated patients (P<0.01, Mann-Whitney test). The respiratory compliance was 80 (73.5, 80) ml cm(-1) H(2)O in the HES-treated patients compared with 60.1 (50.8, 73.3) ml cm(-1) H(2)O in the Gelofusine-treated patients (P<0.01, Mann-Whitney test). The lung injury score 4 h after surgery was less for the patients treated with HES compared with the patients treated with Gelofusine (0.33 vs 0.71, P=0.01, Wilcoxon rank sum test). Mean (SD) plasma elastase was less in the HES-treated patients on the first postoperative day (1.96 (0.17) vs 2.08 (0.24), P<0.05). The log mean microalbuminuria was less in the HES-treated patients (0.41 vs 0.91 mg mmol(-1), P<0.05). This difference in microvascular permeability was associated with different volumes of colloid required to maintain stable cardiovascular measurements in the two groups of patients studied (3000 vs 3500 ml, P<0.01, Mann-Whitney test). CONCLUSION: Compared with Gelofusine, the perioperative pulmonary function of patients treated with HES after abdominal aortic aneurysm surgery was better.

Splanchnic oxygenation in patients undergoing abdominal aortic aneurysm repair and volume expansion with eloHAES.

BACKGROUND: Gastric intramucosal pH (pHi), a surrogate marker of splanchnic oxygenation, falls following abdominal aortic aneurysm surgery. AIM: To investigate the effects of volume expansion with hydroxyethyl starch (eloHAES) on splanchnic perfusion compared to another colloid such as gelofusine. PATIENTS AND METHODS: Twenty-two consecutive patients undergoing AAA repair were randomised to receive either eloHAES or gelofusine as plasma expanders. Tissue oxygenation was monitored (10 gelofusine and 12 eloHAES) indirectly by measuring pHi using a nasogastric tonometer. RESULTS: Compared to the eloHAES group, the fall in pHi was significantly greater in the gelofusine group at clamp release (7.29 vs 7.33, P=0.003) and at 4 h following clamp release (7.29 vs 7.33, P=0.03). There was a good inverse correlation between the lowest pHi and the peak serum interleukin-6 (r(s)= -0.47, P=0.03). By multivariate analysis, the only factor that influenced the pHi was the type of colloid used (F=5.54, P=0.005). The eloHAES treated patients required significantly less colloid on the first postoperative day (3175 +/- 175 vs 4065 +/- 269 ml, P=0.01). CONCLUSION: In patients undergoing abdominal aortic aneurysm repair, plasma expansion with eloHAES improves microvascular perfusion and splanchnic oxygenation.

Gelatine-resorcine-formol glue as a sealant of ePTFE patch suture lines.

BACKGROUND: ePTFE patch reconstruction has superior flow characteristics in preventing early thrombus formation during carotid endarterectomy. However prolonged bleeding at the suture line of the patch reconstruction is a problem. The aim of this study was to investigate whether the application of gelatine-resorcine-formol (GRF) glue at the suture line can improve local haemostasis. METHODS: A prospective randomised trial of 40 consecutive patients undergoing carotid endarterectomy was undertaken. Patients were randomised to receive GRF glue as a topical haemostatic agent or to act as controls. Statistical analysis was performed using the Mann-Whitney test. RESULTS: Although the patch size was significantly smaller in the control group (3.0 cm2 vs 4.3 cm2, p<0.001), local haemostasis was achieved in half the time when the glue was used (11 min vs 22, p<0.004). In the follow-up period ranging from 12 to 24 months, there have been no adverse effects related to the glue. Two patients died during the follow-up period. These deaths were neither related to the patch nor to the glue. CONCLUSIONS: This study has shown that GRF glue is an effective sealant of ePTFE patch suture line. GRF glue does not compromise the patch's characteristics.