Groundwater Nitrogen Pollution and Assessment of Its Health Risks: A Case Study of a Typical Village in Rural-Urban Continuum, China

Protecting groundwater from nitrogen contamination is an important public-health concern and a major national environmental issue in China. In this study, we monitored water quality in 29 wells from 2009 to 2010 in a village in Shanghai city, whick belong to typical rural-urban continuum in China. The total N and NO3-N exhibited seasonal changes, and there were large fluctuations in NH4-N in residential areas, but without significant seasonal patterns. NO2-N in the water was not stable, but was present at high levels. Total N and NO3-N were significantly lower in residential areas than in agricultural areas. The groundwater quality in most wells belonged to Class III and IV in the Chinese water standard, which defines water that is unsuitable for human consumption. Our health risk assessments showed that NO3-N posed the greatest carcinogenic risk, with risk values ranging from 19×10−6 to 80×10−6, which accounted for more than 90% of the total risk in the study area

Effects of two contrasting canopy manipulations on growth and water use of London plane (Platanus x acerifolia) trees

Aims: Two contrasting canopy manipulations were compared to unpruned controls on London plane trees, to determine the effects on canopy regrowth, soil and leaf water relations. Methods: ‘Canopy reduction’, was achieved by removing the outer 30 % length of all major branches and ‘canopy thinning’, by removing 30 % of lateral branches arising from major branches. Results: Total canopy leaf areas recovered within two and three years of pruning for the canopy-thinned and reduced trees respectively. Canopy reduction increased mean leaf size, nitrogen concentration, canopy leaf area density and conserved soil moisture for up to 3 years, whereas canopy thinning had no effects. Another experiment compared more severe canopy reduction to unpruned trees. This produced a similar growth response to the previous experiment, but soil moisture was conserved nearer to the trunk. Analysis of 13C and 18O signals along with leaf water relations and soil moisture data suggested that lower boundary layer conductance within the canopy-reduced trees restricted tree water use, whereas for the canopy-thinned trees the opposite occurred. Conclusions: Only canopy reduction conserved soil moisture and this was due to a combination of reduced total canopy leaf area and structural changes in canopy architecture

Sterowanie nawodnieniami za pomocą technologii czujników wilgotności gleby

Water is a sensitive and limited resource, mainly in intensively used agricultural areas in Austria , where groundwater is used as drinking water as well as for irrigation purposes. In order to guarantee a sustainable use of irrigation water, soil water measurement devices can be used to optimise irrigation, which means that controlling the soil water content in the entire root system may prevent water stress due to water deficiency on the one hand, and over wetting on the other hand. Furthermore, losses of nutrients due to leaching can be avoided. Several research studies on that topic were initiated during the last few years. The soil water status on selected fields planted with different crops (onions, carrots, sugar beets, sweet maize, zucchini) was monitored continuously by FDR (Frequency Domain Reflectometry) soil water measurement devices. Sensors in different depths measure the plant water uptake in the root zone under standard irrigation practices on different sites and different soils, respectively. The deepest sensor is installed to avoid deep percolation caused by over irrigation. By means of these data, irrigation could be regulated based on the actual plant water requirements to keep the soil water content within an ideal range for crop development.W pracy omówiono tematykę ciągłego pomiaru uwilgotnienia gleby z wykorzystaniem najnowszej technologii informatycznej. Podano zarówno podstawy teoretyczne, jak też zagadnienia praktyczne. Opisana technologia polega na zastosowaniu reflektometrów w domenie częstotliwości FDR - wilgotnościomierzy wykorzystujących pomiar pojemności elektrycznej. Urządzenie to umożliwia sterowanie nawodnieniami oraz ciągłe monitorowanie ilości wody magazynowanej w danym czasie w profilu glebowym na określonej głębokości (zasięg 0-80 cm). Przedstawiono wieloletnie wyniki doświadczeń polowych w Austrii, uzyskane na obiektach, na których stosowano metodę sterowania nawodnieniami upraw polowych oraz warzyw w latach 2001-2006. Omówiono dwa różne systemy monitorowania wilgotności gleby w celu sterowania nawodnieniami: Sentek EnviroScan: dane mogą być ładowane w trybie odbioru (do własnego komputera) lub przez modem GSM - ten system wykorzystano w uprawie cebuli, cukinii, kukurydzy pastewnej, marchwi oraz buraków cukrowych; Przekaźnik typu Adcon - zastosowany w uprawie ziemniaków, buraków cukrowych, cebuli, marchwi drobnej oraz fasoli, z czujnikami EasyAG-Sentek umieszczonymi na głębokości 10, 20, 30 i 50 cm. Badania udowodniły, że można zmniejszyć straty wody w nawodnieniach rolniczych dzięki ciągłemu monitorowaniu uwilgotnienia gleby na kilku głębokościach

Numerical Modeling of Nitrate in a Flood‐Irrigated Pecan Orchard

Pecan [(Carya illinoinensis (Wangenh.) K. Koch] is an important specialty crop in New Mexico. This research quantifies soil water and soil nitrate-nitrogen (NO3-N) (mg L-1 of soil) variations with depth, root NO3-N (kg ha-1) uptake, and NO3-N (kg ha-1) balance for the 100-cm soil profile during two growing seasons in a flood-irrigated pecan orchard. Nitrate-nitrogen was determined six times during the growing seasons of 2015 and 2016. The HYDRUS-1D model was used to optimize the water flow parameters using measured volumetric soil water content (q). Model calibration and validation for NO3-N included the optimization of reaction parameters for nitrification and denitrification of each soil layer. The results showed that the model simulated q well (0.44 ≤ d [index of agreement] ≤ 0.73) at different depths during both calibration (2009) and validation (2010) periods. Generally, HYDRUS-1D simulated soil profile NO3-N concentrations that were correlated with measurements at all depths during both years. Total root NO3-N uptake showed a significant increase of 72% in 2016 compared with 2015. The NO3-N balance showed that ∼40% of applied NO3-N per year was denitrified, which was the main contributor to the NO3-N loss from the soil profile during both years. Nitrate-nitrogen leaching below the soil profile was 32 and 26% of applied NO3-N in 2015 and 2016, respectively. The fertigation rate was much higher than the plant demand during both years, and it should be decreased to reduce NO3-N losses