Treatment of landfill leachate using an aerated, horizontal subsurface-flow constructed wetland.

A pilot-scale subsurface-flow constructed wetland was installed at the Jones County Municipal Landfill, near Anamosa, Iowa, in August 1999 to demonstrate the use of constructed wetlands as a viable low-cost treatment option for leachate generated at small landfills. The system was equipped with a patented wetland aeration process to aid in removal of organic matter and ammonia nitrogen. The high iron content of the leachate caused the aeration system to cease 2 years into operation. Upon the installation of a pretreatment chamber for iron removal and a new aeration system, treatment efficiencies dramatically improved. Seasonal performance with and without aeration is reported for 5-day biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), ammonia nitrogen (NH(4)-N), and nitrate nitrogen (NO(3)-N). Since winter air temperatures in Iowa can be very cold, a layer of mulch insulation was installed on top of the wetland bed to keep the system from freezing. When the insulation layer was properly maintained (either through sufficient litterfall or replenishing the mulch layer), the wetland sustained air temperatures of as low as -26 degrees C without freezing problems.

Physical activity as measured by accelerometry in children receiving growth hormone.

AIM: Parents of children treated with growth hormone (GH) frequently report to the paediatrician that their children have become more physically active. In the present study, activity patterns of GH-treated children were measured and compared to those of healthy controls. METHODS: Subjects were 25 children at the start of GH treatment (age 8.4 +/- 2.6 y) and 19 age- and gender-matched controls (age 8.8 +/- 3.2 y). Physical activity was assessed with a tri-axial accelerometer for movement registration over two separate 2-wk intervals, one before the start of GH treatment and one 2 wk after the start of treatment. GH-treated subjects were categorized as poor responders (change in height over 1 y <0.7 SDS, n = 15) or good responders (change in height over 1 y >0.7 SDS, n = 10). RESULTS: Before therapy, good responders showed a significantly lower physical activity compared to healthy controls, spending significantly less time on high-intensity activities. This difference disappeared 2 wk after the start of therapy. Physical activity in poor responders was not significantly different from controls before and after 2 wk of GH therapy. CONCLUSION: Children who respond well to GH therapy (change in height >0.7 SDS) showed a reduced amount of physical activity before therapy, which was normalized after 2 wk of GH therapy.

Physical activity pattern of children assessed by triaxial accelerometry.

OBJECTIVES: Accelerometry was used to assess the relationship between the physical activity level (PAL) and time spent on activities of various intensities in children. DESIGN: A total of 20 children aged 8.6+/-3.3 y wore a triaxial accelerometer (Tracmor2) for 2 weeks. PAL was calculated with Tracmor2 output data. The fraction of time spent on activities with a given level of intensity (low, moderate, high) was calculated. The fractions of time spent on activities of different intensities were compared with previously obtained data for young adults and elderly persons. RESULTS: PAL showed an inverse relation with the percentage of time spent on low-intensity activities (r = -0.76; P < 0.0001) and a positive relation with the percentage of time spent on high-intensity activities (r = 0.93; P < 0.0001). The fraction of time spent on low-intensity activities was smaller in children than in young adults (P < 0.05) and elderly persons (P < 0.0001), while the fraction spent on high-intensity activities (P < 0.0001) was larger. CONCLUSIONS: The present data are important for a better understanding of physical activity in children, which is necessary for education and prevention about physical (in)activity in childhood. Our observations suggest that to obtain a higher PAL in children, they should be given the opportunities to perform high-intensity activities.

Energy expenditure in infants with congenital heart disease, including a meta-analysis.

AIM: To assess energy requirements and body composition in preoperative children with congenital heart disease (CHD). METHODS: In 11 infants with CHD (2-8 mo), total daily energy expenditure (TDEE) and total body water (TBW) were measured with doubly labelled water and compared with historic data from healthy controls. Within the patient group, energy expenditure of infants with versus those without congestive heart failure was compared. Subsequently, the data were pooled with literature data in meta-analyses. RESULTS: CHD patients showed increased TBW (mean +/- SD 66 +/- 3 vs 58 +/- 5% of body weight, p < 0.05) and energy expenditure (381 +/- 42 vs 298 +/- 36 kJ kg(-1) d(-1), p < 0.001). Meta-analyses showed that CHD infants have 35% increased TDEE (376 vs 278 kJ kg(-1) d(-1) , p < 0.00001) and 7% higher TBW (p < 0.0001). Coexistent congestive heart failure (treated with diuretics) had no influence on TDEE (mean difference 14 kJ kg(-1) d(-1) , not significant). In patients with heart failure and growth retardation, an energy balance study showed an average 12% loss of initially ingested energy due to vomiting, increased TDEE and low faecal energy loss, resulting in low energy available for growth, compared with controls (42 +/- 30 vs 96 +/- 61 kJ kg(-1) d(-1) , p < 0.05). CONCLUSION: Many infants with CHD require substantially higher energy intake (at least 100 kJ kg(-1) d(-1) extra) owing to increased TDEE, which is not explained by a higher percentage of body water. Coexistent heart failure does not appear to have an additional influence on TDEE. In infants with CHD and growth failure factors other than elevated TDEE, including vomiting, may explain the disturbed energy balance.

Physical activity levels in children and adolescents.

BACKGROUND: Reference data for physical activity level (PAL) and activity-related energy expenditure (AEE) are needed for a better understanding of the effect of activity on childhood health, growth and development OBJECTIVE: Data from 17 studies measuring TDEE (TDEE) with doubly labelled water DLW were combined to construct a reference line for PAL and AEE as a function of age. DESIGN: A total of 17 studies from the literature were analyzed; 17 on girls and 16 on boys. Children were aged 3-16 y and of Caucasian origin. Weighted least-squares regression was used to obtain reference lines for PAL and AEE as a function of age and gender. The relative numbers of children per study were used as a weighting factor. Basal metabolic rate (BMR) or nonfasted (NF) resting metabolic rate and sex were included in the analysis. RESULTS: Although there was no difference in PAL between boys and girls, a significant difference in AEE was found between the two sexes. PAL: 0.025 x age+1.40. AEE (MJ/day): boys 0.30 x age+0.025; girls 0.21 x age+0.33. If BMR is measured under NF conditions, the obtained value has to be reduced by 0.21 for PAL and 0.75 MJ/day for AEE. No relation was found between AEE/kg and age. CONCLUSIONS: PAL and AEE were found to increase with age, showing the importance of age-dependent recommendations. Recommendations for AEE need to be differentiated for sex. To compare PAL and AEE between studies, the measurement conditions of BMR have to be taken into account. The increase in PAL and AEE values can be attributed to an increase in weight, because there was no relation between AEE/kg and age.