Temporal Stability of Escherichia coli Concentrations in Waters of Two Irrigation Ponds in Maryland
Temporal Stability of Escherichia coli Concentrations in Waters of Two Irrigation Ponds in Maryland
复制标题
马里兰州两个灌溉池塘水中大肠杆菌浓度的时间稳定性
DOI：
10.1128/aem.01876-17
复制
发表时间：
2017
影响因子：
4.4
通讯作者：
M. Kim
中科院分区：
文献类型：
--
作者：
Y. Pachepsky;R. Kierzewski;M. Stocker;K. Sellner;W. Mulbry;Hoonsoo Lee;M. Kim
摘要粪便污染水源是农业灌溉池塘的重要水质问题。大肠杆菌浓度通常用于评估娱乐和灌溉水质。我们假设，可能存在时间稳定的空间格局E。池塘中的大肠杆菌浓度，这意味着某些地区的大肠杆菌浓度大多高于平均浓度，而其他地区的大肠杆菌浓度大多低于平均浓度。杆菌为了验证这一假设，我们在2016年夏天每两周在马里兰州的空间网格节点处对两个灌溉池塘进行采样。环境协变量-温度，浊度，电导率，pH值，溶解氧，叶绿素a和营养物质-与E。大肠杆菌浓度。时间稳定性进行了评估，在每个位置的测量值和平均测量跨池塘之间的平均相对差异。时间稳定的空间格局E。大肠杆菌浓度和大多数环境协变量表示为两个池塘。在池塘内部，较大的叶绿素a的相对平均差异对应于较小的平均相对差异在E。大肠杆菌浓度，斯皮尔曼等级相关系数为0.819。氨氮和氨氮浓度是另外两个环境协变量，它们的位置等级与E。大肠杆菌浓度位置排名。几何平均E.大肠杆菌的浓度一直高或一直低。证明了E.大肠杆菌浓度会影响池塘中微生物水质评价的结果，在微生物水质监测设计中应考虑到这一点。重要性必须对灌溉水源中的微生物质量进行评估，以防止因农产品消费而导致人类疾病的微生物传播。以大肠杆菌为指示生物，评价灌溉水微生物质量。由于E.为了监测灌溉水源中的大肠杆菌浓度，需要就在何处和何时采集水样进行微生物分析提出建议。这项工作表明，存在一个时间稳定的空间格局中的分布E。整个灌溉池塘的大肠杆菌浓度。研究的池塘有E.大肠杆菌浓度大多高于平均值，而在整个观察期间，浓度大多低于平均值的区域，涵盖了用水灌溉的季节。考虑到这些区域的存在，将改善微生物水质监测的设计和实施。
ABSTRACT Fecal contamination of water sources is an important water quality issue for agricultural irrigation ponds. Escherichia coli concentrations are commonly used to evaluate recreational and irrigation water quality. We hypothesized that there may exist temporally stable spatial patterns of E. coli concentrations across ponds, meaning that some areas mostly have higher and other areas mostly lower than average concentrations of E. coli. To test this hypothesis, we sampled two irrigation ponds in Maryland at nodes of spatial grids biweekly during the summer of 2016. Environmental covariates—temperature, turbidity, conductivity, pH, dissolved oxygen, chlorophyll a, and nutrients—were measured in conjunction with E. coli concentrations. Temporal stability was assessed using mean relative differences between measurements in each location and averaged measurements across ponds. Temporally stable spatial patterns of E. coli concentrations and the majority of environmental covariates were expressed for both ponds. In the pond interior, larger relative mean differences in chlorophyll a corresponded to smaller mean relative differences in E. coli concentrations, with a Spearman's rank correlation coefficient of 0.819. Turbidity and ammonium concentrations were the two other environmental covariates with the largest positive correlations between their location ranks and the E. coli concentration location ranks. Tenfold differences were found between geometric mean E. coli concentrations in locations that were consistently high or consistently low. The existence of temporally stable patterns of E. coli concentrations can affect the results of microbial water quality assessment in ponds and should be accounted for in microbial water quality monitoring design. IMPORTANCE The microbial quality of water in irrigation water sources must be assessed to prevent the spread of microbes that can cause disease in humans because of produce consumption. The microbial quality of irrigation water is evaluated based on concentrations of Escherichia coli as the indicator organism. Given the high spatial and temporal variability of E. coli concentrations in irrigation water sources, recommendations are needed on where and when samples of water have to be taken for microbial analysis. This work demonstrates the presence of a temporally stable spatial pattern in the distributions of E. coli concentrations across irrigation ponds. The ponds studied had zones where E. coli concentrations were mostly higher than average and zones where the concentrations were mostly lower than average over the entire observation period, covering the season when water was used for irrigation. Accounting for the existence of such zones will improve the design and implementation of microbial water quality monitoring.