The North China Plain,where summer corn(Zea mays L.)and winter wheat(Triticum aestivum L.)are the major crops grown,is a major agricultural area in China.Permeable soils make the region susceptible to groundwater poll...The North China Plain,where summer corn(Zea mays L.)and winter wheat(Triticum aestivum L.)are the major crops grown,is a major agricultural area in China.Permeable soils make the region susceptible to groundwater pollution by NO_3-N,which is applied to fields in large amounts of more than 400 kg NO_3-N ha^(-1)as fertilizer.A field experiment was established in 2002 to examine the relationship among N fertilization rate,soil NO_3-N,and NO_3-N groundwater contamination.Two adjacent fields were fertilized with local farmers' N fertilization rate(LN)and double the normal application rate(HN),respectively,and managed under otherwise identical conditions.The fields were under a traditional summer corn/winter wheat rotation.Over a 22-month period,we monitored NO_3-N concentrations in both bulk soil and soil pore water in 20-40 cm increments up to 180 cm depth.We also monitored NO_3-N concentrations in groundwater and the depth of the groundwater table.No significant differences in soil NO_3-N were observed between the LN and HN treatment.We identified NO_3-N plumes moving downward through the soil profile.The HN treatment resulted in significantly higher groundwater NO_3-N,relative to the LN treatment,with groundwater NO_3-N consistently exceeding the maximum safe level of 10 mg L^(-1),but groundwater NO_3-N above the maximum safe level was also observed in the LN treatment after heavy rain.Heavy rain in June,July,and August 2003 caused increased NO_3-N leaching through the soil and elevated NO_3-N concentrations in the groundwater.Concurrent rise of the groundwater table into NO_3-N- rich soil layers also contributed to the increased NO_3-N concentrations in the groundwater.Our results indicate that under conditions of average rainfall,soil NO_3-N was accumulated in the soil profile.The subsequent significantly higher- than-average rainfalls continuously flushed the soil NO_3-N into deeper layers and raised the groundwater table,which caused continuous groundwater contamination with NO_3-N.The results suggest that under common farming practices in the North China Plain,groundwater contamination with NO_3-N was likely,especially during heavy rainfalls,and the degree of groundwater contamination appeared to be proportional to the N application rates.Decreasing fertilization rates, splitting fertilizer inputs,and optimizing irrigation scheduling had potential to reduce groundwater NO_3-N contamination.展开更多
目的了解邯郸地区玉米和小麦及其制品中交链孢霉毒素的污染状况,评估邯郸地区玉米和小麦制品中交链孢霉毒素的膳食暴露风险。方法采用超高效液相色谱-串联质谱同位素稀释内标法对邯郸地区生产市售的玉米和小麦及其制品共148份(玉米57份...目的了解邯郸地区玉米和小麦及其制品中交链孢霉毒素的污染状况,评估邯郸地区玉米和小麦制品中交链孢霉毒素的膳食暴露风险。方法采用超高效液相色谱-串联质谱同位素稀释内标法对邯郸地区生产市售的玉米和小麦及其制品共148份(玉米57份,小麦61份,小麦制品30份)进行交链孢霉毒素的检测和定量,并采用毒性学关注阈值(threshold of toxicological,TTC)进行成人的膳食暴露风险评估。结果玉米和小麦及其制品中交链孢霉毒素均有检出,其中57份玉米样品中40份检出交链孢霉毒素,膳食暴露量均低于TTC值;91份小麦及其制品中均检出交链孢霉毒素,小麦的检出率和检出浓度均高于小麦制品,小麦制品的膳食暴露量均值低于TTC值。玉米和小麦及其制品中多种交链孢霉毒素共存的现象普遍存在,4种交链孢霉毒素的相关性极高。结论邯郸地区的玉米和小麦及其制品均受到4种交链孢霉毒素不同程度的污染。玉米污染程度较低,小麦及其制品污染程度较高。玉米和小麦制品正常摄入水平膳食暴露风险均较小。但不同交链孢霉毒素间的协同作用可能会增加真菌毒素的毒性作用。因此邯郸地区仍需持续监测并采取多种措施降低谷物中交链孢霉毒素的污染。展开更多
基金Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(No.kzc x2-yw-406)the National Basic Research Program of China(No.2005CB121103).
文摘The North China Plain,where summer corn(Zea mays L.)and winter wheat(Triticum aestivum L.)are the major crops grown,is a major agricultural area in China.Permeable soils make the region susceptible to groundwater pollution by NO_3-N,which is applied to fields in large amounts of more than 400 kg NO_3-N ha^(-1)as fertilizer.A field experiment was established in 2002 to examine the relationship among N fertilization rate,soil NO_3-N,and NO_3-N groundwater contamination.Two adjacent fields were fertilized with local farmers' N fertilization rate(LN)and double the normal application rate(HN),respectively,and managed under otherwise identical conditions.The fields were under a traditional summer corn/winter wheat rotation.Over a 22-month period,we monitored NO_3-N concentrations in both bulk soil and soil pore water in 20-40 cm increments up to 180 cm depth.We also monitored NO_3-N concentrations in groundwater and the depth of the groundwater table.No significant differences in soil NO_3-N were observed between the LN and HN treatment.We identified NO_3-N plumes moving downward through the soil profile.The HN treatment resulted in significantly higher groundwater NO_3-N,relative to the LN treatment,with groundwater NO_3-N consistently exceeding the maximum safe level of 10 mg L^(-1),but groundwater NO_3-N above the maximum safe level was also observed in the LN treatment after heavy rain.Heavy rain in June,July,and August 2003 caused increased NO_3-N leaching through the soil and elevated NO_3-N concentrations in the groundwater.Concurrent rise of the groundwater table into NO_3-N- rich soil layers also contributed to the increased NO_3-N concentrations in the groundwater.Our results indicate that under conditions of average rainfall,soil NO_3-N was accumulated in the soil profile.The subsequent significantly higher- than-average rainfalls continuously flushed the soil NO_3-N into deeper layers and raised the groundwater table,which caused continuous groundwater contamination with NO_3-N.The results suggest that under common farming practices in the North China Plain,groundwater contamination with NO_3-N was likely,especially during heavy rainfalls,and the degree of groundwater contamination appeared to be proportional to the N application rates.Decreasing fertilization rates, splitting fertilizer inputs,and optimizing irrigation scheduling had potential to reduce groundwater NO_3-N contamination.
文摘目的了解邯郸地区玉米和小麦及其制品中交链孢霉毒素的污染状况,评估邯郸地区玉米和小麦制品中交链孢霉毒素的膳食暴露风险。方法采用超高效液相色谱-串联质谱同位素稀释内标法对邯郸地区生产市售的玉米和小麦及其制品共148份(玉米57份,小麦61份,小麦制品30份)进行交链孢霉毒素的检测和定量,并采用毒性学关注阈值(threshold of toxicological,TTC)进行成人的膳食暴露风险评估。结果玉米和小麦及其制品中交链孢霉毒素均有检出,其中57份玉米样品中40份检出交链孢霉毒素,膳食暴露量均低于TTC值;91份小麦及其制品中均检出交链孢霉毒素,小麦的检出率和检出浓度均高于小麦制品,小麦制品的膳食暴露量均值低于TTC值。玉米和小麦及其制品中多种交链孢霉毒素共存的现象普遍存在,4种交链孢霉毒素的相关性极高。结论邯郸地区的玉米和小麦及其制品均受到4种交链孢霉毒素不同程度的污染。玉米污染程度较低,小麦及其制品污染程度较高。玉米和小麦制品正常摄入水平膳食暴露风险均较小。但不同交链孢霉毒素间的协同作用可能会增加真菌毒素的毒性作用。因此邯郸地区仍需持续监测并采取多种措施降低谷物中交链孢霉毒素的污染。
