Molecular subtyping for source tracking of Escherichia coli using core genome multilocus sequence typing at a food manufacturing plant

When harmful bacteria are detected in the final product at a food manufacturing plant, it is necessary to identify and eliminate the source of contamination so that it does not occur again. In the current study, the source of contamination was tracked using core genome multilocus sequence typing (cgMLST) analysis in cases where Escherichia coli was detected in the final product at a food manufacturing plant. cgMLST analysis was performed on 40 strains of E. coli collected from the environment [floor (26 strains), drainage ditch (5 strains), container (4 strains), post-heating production line (1 strain)] and products [final product (3 strains) and intermediate product (1 strain)]. In total, 40 E. coli isolates were classified into 17 genogroups by cgMLST analysis. The 4 E. coli strains isolated from the intermediate and final products were classified into two genogroups (I and II). Certain isolates collected from the environment also belonged to those genogroups, it was possible to estimate the transmission of E. coli in the manufacturing plant. Thus, the dynamics of E. coli in the food manufacturing location were clarified by using cgMLST analysis. In conclusion, our results indicate that cgMLST analysis can be effectively used for hygiene management at food manufacturing locations.

Optimized Main Ditch Water Control for Agriculture in Northern Huaihe River Plain, Anhui Province, China, Using MODFLOW Groundwater Table Simulations

Controlled drainage by regulating the groundwater level in open ditches is necessary to ensure the normal growth of crops in Northern Huaihe River Plain, China. The groundwater model MODFLOW was calibrated and validated in a representative area, and was then conducted to simulate the groundwater under different main drainage ditch water depth control schemes during the growth period of corn and wheat. Then the scenario with highest water depth (Scenario 20) from 1989 to 2019 was simulated, and the annual cumulative drought and waterlogging intensity (ACDWI) were analyzed in each decade and in different hydrological years. The results showed that the study area was dominated by drought stress. The lowest level of drought stress was achieved under Scenario 20. The frequency of drought gradually decreased from north to south in the study area. Moreover, the ACDWI decreased with increase of precipitation during 1989 to 2019. The results indicated that it was important to store water during the dry season, while it is also necessary to control the drainage in the rainy season to drain excess water on time. The results suggested that the water depth of the main drainage ditch should be regulated by zoning and by season to alleviate crop drought and waterlogging.

Rate of Fen-Peat Soil Subsidence Near Drainage Ditches (Central Poland)

This study analyzed design depths (to), post-subsidence depths (t), shallowing magnitudes (d = to − t) and ratio values (d/t) of 12 drainage ditches in a fragment of the drained Solec fen-peat (central Poland) over a period of 47 years between 1967 and 2014. A significant decrease of the designed depth of the ditches to was shown, from the average designed value of 0.97 m to their average depth after subsidence, t = 0.71 m. The ratio (d/t) of 0.41, which is associated with the degree of organic matter decomposition, indicated medium degree of peat decomposition. The average values of bank and bottom subsidence of the ditches during the analyzed period, 1967–2014, were 0.43 m and 0.17 m, respectively. The values of the average annual rate of land surface subsidence in the vicinity of the ditches were varied and within the range of 0.09 cm year−1 to 1.70 cm year−1, with an average of 0.92 cm year−1. Two linear empirical equations were proposed to calculate the amount of subsidence and the average annual rate of subsidence of peat soil surface near the drainage ditch route, based on the knowledge of the initial thickness of the peat deposit. The results of calculations using the equations proposed by the authors were compared with calculations of the same parameters using 10 equations published in the literature. The results obtained using the proposed equations were mostly larger than those calculated with literature-published equations.

Modeling Tidal Characteristics in a Creek-Marsh Drainage System: Implications for Stormwater Management

The traditional goal of stormwater management is to reduce the threat of flooding to life and property, and so most landscapes are engineered to maximize the speed at which the unwanted water leaves the watershed. This has been effective in landscapes with some topographic gradient. This often involves the installation of drainage ditches that disperse runoff from urban areas to receiving water bodies; in coastal areas this means a tidal creek, estuary, bay, sounds, or the coastal ocean. This practice reduces flood hazards in some cases but results in unintended effects on the natural hydrology in the watershed and downstream tidal dynamics. For low-gradient watersheds in humid climates, ditch systems also lower the water table of an area, increasing infiltration to recharge and groundwater discharge to streams (baseflow), and larger volume of freshwater delivered downstream yearround. Ditches also create unintentional avenues for the incoming tide from a tidal creek or tidally-influenced waterway to reach further inland, thus reducing the hydraulic gradient between the inland areas and the receiving water body. The combination of these effects can exacerbate compound flooding events, increasing the flood probability if high tide and storm events coincide. Additionally, coastal communities face the challenge of mitigating more complicated flood hazards while land development increases to meet the needs of a growing population. This study analyzed the tidal influence within an inland drainage ditch in the central coast of South Carolina USA that is representative of thousands of artificially-drained coastal watersheds. The ditch-creek system investigated here is 12 km long in a 753-hectare (1860-acre) watershed of Church Flats Creek, a first-order tidal system. We monitored for 13 months a 0.75-km reach of the lower ditch portion of the system, just above the relatively undisturbed tidal creek and marsh. Prior to ditching in the 1960s this system had a wetland-rich floodplain but is now partially tidal. Field data collected were stream stage (depth), discharge, tidal range, tidal volume, incoming (flood) and outgoing (ebb) tidal durations, and water table hydrograph at a location about 50 m of mid-reach of the ditch. Multiple linear regressions were performed to best predict the flood and ebb tidal durations of the system based on tidal characteristics within the ditch. The mean values were 229 ± 2.5 and 182 ± 2.1 minutes for flood and ebb tide durations, respectively and the models explained 84% (residual standard error (RSE) of 25 minutes) and 80% (RSE of 23 minutes) for the flood and ebb conditions, respectively. The models were simulated for sea levels in 1993 and 2050, and results indicate that the flood tide within the drainage ditch is predicted to increase an average of 66 minutes and the total tidal duration (flood and ebb) an average of 139 minutes by 2050. These results suggest a loss in drainage functionality as sea level rises. Increases in the duration of tidal influence will induce a lower capacity for stormwater volume than the drainage infrastructure was constructed to manage, therefore resulting in an increased frequency of compound flooding events because of the lower storage volume and decreased hydraulic gradient in the system. This study fills a knowledge gap of tidal dynamics within coastal ditch-creek systems and we urge stormwater managers to consider the unintended consequences of using traditional stormwater methods in a region that does not benefit from gravity drainage practices like in other regions.

The streamwise velocity distribution in a two-stage channel with ice cover

The problem of agricultural non-point source pollution has become increasingly serious. How to determine the ecological drainage ditch system is one of the effective methods to solve the agricultural non-point source pollution. This research study focuses on the velocity distribution in a two-stage section ecological channel with ice cover. The results show that the two-stage section channel with ice cover can effectively reduce the flow velocity in the channel and increase the retention time of water in the channel. By comparing with the experimental data, the accuracy of the analytical solution is high, which provides a theoretical reference for the transport of sediment and pollutions in a two-stage section channel with ice cover in the future.