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 g_FW⁻¹) on vegetables and from 1.7 to 2.1 (WS) and from 0.6 to 1.0 (DS) log₁₀CFU per gram dry weight (g_DW⁻¹) in soil. Average log₁₀CFU g_FW⁻¹ rates of 6.19 and 3.44 fecal coliform were found on vegetables, whereas in soil, 4.26 and 4.58 log₁₀CFU g_DW⁻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.

中文翻译：

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加纳北部城市农业生态系统中的病原体和重金属污染：生物炭应用和废水灌溉的影响

生物炭作为土壤肥力增强剂的好处是众所周知的，并已被广泛研究。同样，许多热带和亚热带国家在都市农业中使用废水进行灌溉。为了评估相关的健康风险，我们确定了与加纳北部城市农业中生物炭应用和废水灌溉相关的病原体和重金属的归宿。在田间试验中对水稻 ( Oryza  L.) 壳生物炭 (20 t ha ^-1 )、N-P-K 15-15-15 肥料 (212.5 kg ha ^-1 ) 及其组合进行了评估。未经处理的废水和自来水用作灌溉用水。红苋菜 ( Amaranthus cruentusL.) 用作试验作物并在湿 (WS) 和干 (DS) 作物季节种植。对灌溉水、土壤和蔬菜中的重金属、大肠杆菌、粪便大肠菌群、蠕虫卵和沙门氏菌进行了分析。与病原体不同，来自灌溉水和土壤的分析重金属低于粮农组织/世卫组织允许的农业活动标准。废水灌溉导致蔬菜上的大肠杆菌浓度为 0.5 至 0.6 (WS) 和 0.7 至 0.8 (DS) log ₁₀菌落形成单位每克鲜重 (CFU g _FW ^-1 ) 和 1.7 至 2.1 (WS) 和从 0.6 到 1.0 (DS) log ₁₀ CFU 每克干重 (g _DW ^-1) 在土壤中。在蔬菜上发现平均 log ₁₀ CFU g _FW ^-1比率为 6.19 和 3.44 粪便大肠菌，而在土壤中，分别在 WS 和 DS 中观察到4.26 和 4.58 log ₁₀ CFU g _DW ^-1。废水中的蠕虫卵种群数量较多，并转移到作物和土壤中。Biochar 不影响细菌污染。蔬菜和土壤中的病原体污染与灌溉水直接相关，从生物炭应用中观察到的差异很小或没有差异。