Investigation of N and P Non-Point Source Pollution Status of Vegetable Fields in the Suburb of Fuzhou City (2010)

N and P non-point source pollution status of vegetable fields in the suburb of Fuzhou city was evaluated by testing samples of vegetable (120 samples), soil surface water (16 samples) and groundwater (11 samples) collected from 14 pieces of vegetable fields which were located at the suburb of that city according to the related criteria in this paper. Results showed that (1) Proportions of vegetable samples of which nitrate content fell into serious pollution level (NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> ≥3 100 mg·kg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ), heavy pollution level (NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> ≥ 1 440 mg·kg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) and moderate pollution level (NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> ≥ 785 mg·kg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) were 13.33%, 32.5% and 50.83%, respectively. (2) Proportions of soil surface water samples of which ammonia nitrogen content was beyond the water quality criteria of Grade III (1 mg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) and Grade V (2 mg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) were 62.5% and 56.25% in vegetable field, respectively. The proportion of soil surface water samples of which nitrate nitrogen content was beyond the water quality criterion of the national centralized drinking water standards for surface water (10 mg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) was 12.5% in vegetable field. Compared with the surface water quality criteria of Grade V (2 mg N L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , 0.4 mg P L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ), the average and maximal total N, P content of soil surface water samples of vegetable were 10.99 and 33.80 mg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , 4.75 and 12.75 mg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , respectively. (3) The proportion of vegetable field groundwater samples of which ammonia-N content was beyond the water quality criteria of Grade V (0.5 mg·L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) was 18.18%. Proportions of groundwater samples of which nitrate content was super-scale (≥10 mg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) and serious super-scale (≥20 mg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) were 54.55% and 27.27%, respectively. The content of total N of all groundwater samples detected was beyond the water quality criteria of Grade V (2 mg N L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , GB3838-2002). And the proportion of vegetable field groundwater samples of which total P content was beyond the water quality criteria of Grade V (0.4 mg P L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , GB3838-2002) was 81.82%.