Pathogen and heavy metal contamination in urban agroecosystems of northern Ghana: Influence of biochar application and wastewater irrigation.

The benefit of biochar as a soil fertility enhancer is well known and has been broadly investigated. Equally, many tropical and subtropical countries use wastewater for irrigation in urban agriculture. To assess the related health risks, we determined pathogen and heavy metal fate associated with biochar application and wastewater irrigation in the urban agriculture of northern Ghana. Rice (Oryza L.) husk biochar (20 t ha-1 ), N-P-K 15-15-15 fertilizer (212.5 kg ha-1 ), and their combinations were evaluated in a field-based experiment. Untreated wastewater and tap water served as irrigation water. Red amaranth (Amaranthus cruentus L.) was used as a test crop and was grown in wet (WS) and dry (DS) cropping seasons. Irrigation water, soil, and vegetables were analyzed for heavy metals, Escherichia coli, fecal coliform, helminth eggs, and Salmonella spp. Unlike the pathogens, analyzed heavy metals from irrigation water and soil were below the FAO/WHO permissible standard for agricultural activities. Wastewater irrigation caused E. coli concentrations ranging from 0.5 to 0.6 (WS) and from 0.7 to 0.8 (DS) log10 colony forming units per gram fresh weight (CFU gFW -1 ) on vegetables and from 1.7 to 2.1 (WS) and from 0.6 to 1.0 (DS) log10 CFU per gram dry weight (gDW -1 ) in soil. Average log10 CFU gFW -1 rates of 6.19 and 3.44 fecal coliform were found on vegetables, whereas in soil, 4.26 and 4.58 log10 CFU gDW -1 were observed in WS and DS, respectively. Helminth egg populations were high in wastewater and were transferred to the crops and soil. Biochar did not affect bacteria contamination. Pathogen contamination on vegetables and in soil were directly linked to the irrigation water, with minimal or no difference observed from biochar application.

Comparing Different Methods of Measuring Accommodative Amplitude with Hofstetter's Normative Values in a Ghanaian Population.

AIM: Amplitude of accommodation (AoA) can be determined clinically using different methods. Some methods are known to be more reliable than others for measuring AoA in different age categories. The purpose of this study was to compare Hofstetter's age-expected norms with five recommended methods of measuring AoA in order to determine age-appropriate techniques for a Ghanaian population. MATERIALS AND METHODS: AoA was measured using four subjective methods (push-up, push-down, minus lens, and modified push-up) and one objective method, the modified dynamic retinoscopy. The amplitudes obtained by each technique were compared to each other and also compared to the age-expected amplitudes as predicted by Hofstetter's equations. RESULTS: 352 non-presbyopes aged 10-39 years were included in this study. All five methods except the push-up (p = 0.089) and modified push-up (p = 0.081) differed significantly from Hofstetter's data, while the modified dynamic retinoscopy recorded the strongest agreement with Hofstetter's average (ICC = 0.78, p Ë‚ 0.001). With reference to Hofstetter's expected AoA, the minus lens, push-down, modified dynamic retinoscopy, and modified push-up methods underestimated AoA by -4.18D, -1.99D, -0.48D, and -0.43D, respectively. As age increased, underestimated AoA values by the minus lens (10-19 years: -5.57D, 20-29 years: -3.50D, 30-39 years: -2.39D), modified push-up (10-19 years: -1.51D, 20-29 years: +0.40D, 30-39 years: +0.56D), and push-down (10-19 years: -2.90D, 20-29 years: -1.07D, 30-39 years: -1.46D) methods decreased but the modified push-up in relation to Hofstetter's expected was most accurate for the older age. The push-up, on the other hand, overestimated accommodation in all age categories by +0.42D (10-19 years: +0.01D, 20-29 years: +0.82D, 30-39 years: 0.67D). Thus, the push-up method became more accurate as age decreased. CONCLUSION: This study suggested that Hofstetter's formulae could be used to predict the amplitudes of Ghanaian non-presbyopes aged 10-39 years using the push-up and modified push-up. With regard to Hofstetter's data, the push-up method was more accurate for the younger age-group 10-19 years while the modified push-up was more accurate for the older age-group 20-39.