Agriculture Reference
In-Depth Information
With the population increase and urban sprawl of Beijing, mountain
agriculture has played increasingly important roles in areas such as ser-
vices, the economy, ecological security and tourism. Figure 2 shows that
the gross value of agricultural output in the study area increased quickly
with the pressure for arable land resources in plain areas that have be-
come non-agricultural land owing to city sprawl, particularly in the high
development periods of the mid 1990s. The past studies suggested that
the increase in agricultural output mainly depended on the input of a large
amount of non-renewable resources, especially agricultural chemical fer-
tilizers, pesticides and plastic fi lm, according to the correlation analyses
of agricultural inputs and outputs in 2000 [24]. The main non-renewable
agricultural inputs have still increased in recent decade years, which has
led to greatly increased environmental damage such as water pollution,
soil contamination and air pollution caused by agriculture, especially high
intensity industrialized agriculture.
1.2.2 SURFACE WATER QUALITY DATA
There are 27 monitoring sites in the study area. The monitoring Sites 1-8,
9-13, 14-17, 18-25 and 26-27 correspond to the Chaobai River, Juyun
River, Beiyun River, Yongding River and Daqing River watersheds, re-
spectively (Figure 1). The streams on which they are respectively located
are listed in Table 1. Water samples were taken at these stations monthly
from May to October 2000. Of these, June, July, August and November
in 2000 were the rainy reason, and the rest was the dry season. A total
of 162 samples were collected at the 27 sites of the Beijing mountain-
ous areas. Water samples were analyzed in the laboratory for eight water
quality characteristics, including nitrate-nitrogen (NO 3 -N), permanganate
index (COD Mn ), biochemical oxygen demand for five days (BOD 5 ), total
nitrogen (TN), total phosphorus (TP), total mercury (Hg), total cadmium
(Cd) and total lead (Pb). Then the monthly average values of water quality
characteristics for each site were derived, which were used for our statisti-
cal assessment.
 
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