Posted July 1998
See also: Environment Specials
Not that environmental conditions were better during the earlier central planning era - in fact, central planning still has a major influence in the the agricultural economy, but the proliferation of privately owned small-scale industries is substantially adding to the pollution load already generated by highly polluting state-owned industries that rely heavily on coal. An additional factor has been the inability of planners to control the mix between industrial activities and agriculture production. In a number of cases, this has led to contamination of soil and water and the entry of pollutants into the food chain.
While these factors are affecting air, soil, water as well as food quality and safety, agriculture itself is not immune against criticism. Data are scarce but point to a large number of environmental problems. Deforestation was rampant during the fifties and sixties and erosion rates from some farmlands are among the highest in the world. For example, in the Loess Plateau, rates approach 300 metric tons per hectare per year (MT ha-1yr-1). The average national rate (approx. 30 MT ha-1yr-1) is three times the maximum recommended rate. In addition, the use of agricultural chemicals (i.e. mineral fertilizers and pesticides) in China's most productive areas surpass levels that are used in Europe and US; notwithstanding this, some areas are experiencing a leveling off in grain production. There has also been a significant decline in water quality, in particular, in tributaries of large water bodies.
Important is the limited ability of China to deal with its environmental pollution problems. Allocation of resources for environmental protection and management has been at minimal levels and suggested environmental policies have often been perceived as jeopardizing China's ambitious development goals. Nonetheless, China is starting to understand that environmental degradation means economic costs; the acquisition of environmental data to quantify the impacts of environmental degradation, and using these to adopt policy changes is now receiving higher priority.
FAO has assisted Hubei Province in Central China to enhance its environmental data acquisition and management capacity by strengthening the Hubei Agro-Environmental Protection Station (hereafter called the Station) in its capacity to identify, analyze, monitor and report on the levels of pollutants in water, soil and crops in the province. Methods were developed to estimate the economic cost of both industrially and agriculturally generated pollution. The Station employs a province-wide staff of 1,200 persons and has the mandate to monitor environmental conditions in the agricultural system (water, soil, crop, fishery) and enforce environmental regulations.
Because of uncertainty as to the extent, magnitude, type and geographical distribution of the pollutants, the first step was to compile and analyze all available data to help establish the "State-of-the-Environment in Hubei". An environmental survey was carried out with the help of the 60 environmental sub-stations of the province. Data and information, which differed widely in scale and detail, was entered in a database that served as a repository for all environmental data in the province.
With the help of the HydroQual consulting firm, maps of the province and its major features were digitized and a Geographic Information System (GIS) was developed to organize, store, manipulate and better visualize the data entries. This effort helped establish, albeit with large uncertainty due to data limitations, the general environmental trends and identify data gaps and needs. It also helped prioritize future interventions and design a monitoring plan that focuses on the areas that needed immediate action.
A parallel effort was devoted to upgrading the analytical facilities of the Station through the acquisition of new equipment (gas chromatograph-GC, atomic absorption spectrophotometer (AAS), analytical balances, various laboratory instruments, computers, software, etc.). Training of the Station's personnel on operating the newly acquired analytical instruments and on data management procedures was also carried out.
Three workshops, held in 1996 and 1997, were devoted to environmental monitoring, best management practices (BMPs) and environmental statistics. The leading chemist at the Station was trained on modern chemical analytical techniques in the US at Columbia Analytical Services (CAS) in Rochester, NY, at Rutgers University, and at HydroQual Offices in Mahwah, NJ. A measurement campaign was also initiated according to a monitoring plan tailored to the available resources and immediate needs of the province.
The Province of Hubei is situated in central China in the middle reaches of the Yangtze River. With a population of 57 million and an area of 185,000 km2, the province has about 320 lakes with a storage capacity of 3 billion m3 and 1,190 rivers including 42 rivers that are longer than 100 km (Figure 1). As the most important water body, the Yangtze river flows west to east over a length of 1,061 km with an average flow rate of 23,400 m3/s (i.e., 76,100 m3/s maximum and minimum 2,930 m3/s) and carries an average of 430 millions tons of sediments. Hubei, in general, and the Yangtze river basin, in particular, have a sub-tropical monsoon climate in which most of the yearly precipitation occurs between May and September. The Yangtze River basin itself can receive in excess of 1,100 mm of rainfall per year. This uneven seasonal precipitation and the recurring low-precipitation years, often lead to flood and drought events in the spring and late autumn.
Under normal circumstances, answers to such questions require a thorough analysis of environmental data pertaining to the province. Because historical and sometimes recent data were not available or inaccessible, answers rest on environmental analyses using data that is sometimes unchecked or not cross-referenced. It is well known that many of China's agriculture and land statistics are either under- or over-reported. For instance, arable land estimates recently revised upwards from 80 million ha. to 130 million; there is a general consensus that cultivated area is underreported by around 30 percent; and effluent treatment levels are often significantly overestimated. Therefore, the following explanations have to be interpreted with caution, until a sound monitoring program is full in place.
There were instances in 1986-1990 and 1991-1995 when water quality parameters were exceeded in the main section of the Yangtze, in particular, suspended solids, polyaromatic hydrocarbons, ammonium, dissolved oxygen and volatile phenols. This suggests that municipal wastewater discharges are beginning to have an impact on water quality in the densely populated reaches of the Yangtze. A more systematic monitoring campaign is essential to establish a definitive trend, if any, to translate instantaneous values into daily and monthly averages. Such averages might be better indicators of the actual health status of the Yangtze.
Of more concern, however, is the impairment of smaller water bodies like streams, small lakes and some of the Yangtze tributaries. In the vicinity of Wuhan, the East Lake, a receiving water body, water quality has drastically deteriorated in recent year and the lake has become eutrophic in many areas. Major pollutants exceed class IV standards. The relative shallowness of the lake (i.e., approx. 2.50 m) exacerbates the eutrophication phenomenon. The Moshui lake in the Hanyang district of Wuhan, although deeper (i.e., approx. 19 m) than the East Lake, receives almost two third of its input from domestic and industrial wastewater: COD, BOD5, TP and TN all exceed even class V standards. As a result the Moshui Lake has lost its economic use and has become a waste sink. Moreover, unless wastewater is diverted directly to the Yangtze, in the year 2000, the total phosphorus loads entering the Ci Lake, are expected to reach 4.54 gm-3yr-1 that will dramatically increase the chlorophyll concentration from a current 14.3 (g L-1 to more than 160 (g L-1. The Ci Lake is an already eutrophic water body located near the second biggest provincial city, Huangshi. Conditions are usually considered eutrophic once the chlorophyll concentration exceeds 10 (g L-1).
Use is gradually shifting towards lower class standards for lakes or river reaches that were still healthy a decade ago. The role of agricultural point sources towards the degradation of water quality in those systems is not clear. Some of the nutrient loads in particular, nitrogen and phosphorus are prevalent in both municipal and agricultural runoff.
Some estimates, suggest that 64% of nitrogen supplied on Chinese soil are lost through runoff, leaching and denitrification. Assuming that nitrogen constitutes approx. 48% of the fertilizers applied, the estimated losses of N in Hubei will be approx. 98 kg/ha. Similar rates in the U.S. from nonpoint sources have led to the impairment of 60% of river miles, 59% of lake areas, 28% of estuaries, and 94% of wetlands. Although large rivers with significant river flows like the Yangtze are unlikely to be affected, it is probable that water quality in smaller canals, lakes, as well as tributaries of the larger rivers, is already impaired by the presence of excess nitrate, in particular in areas of agricultural productions. In fact, high nitrogen levels were found in irrigation, breed and drinking waters of one county that has low rates of domestic wastewater discharges, but notoriously high rates of fertilizers and pesticides utilization. Although, the cause-effect relationship is not clearly established, the source of nitrogen is probably from agricultural runoff. A better assessment of the impact of fertilizers application rates is to monitor the quality of drainage water and groundwater. However, monitoring is confined to the large water bodies at the expense of middle and small size rivers, streams and lakes, where impacts are more likely to occur.
There are also indications that farmlands situated in the vicinity of polluting industries have deposits of trace metals at elevated concentrations. The concern is that crops exposed to high levels of heavy metals in soils could accumulate those elements and pose health hazards to the consumer of the food crop. A well-publicized case of cadmium pollution in Hubei is in Daye and Huangshi cities, where significant land areas were taken out of production as a result of excessive exposure to air-borne and water -borne sources of cadmium and copper. Emissions from smelters, mining and fertilizers industries have disseminated both elements in the surrounding environment. Relative to a background concentration of 0.18 mg/kg in uncontaminated soils, cadmium levels in heavily polluted farmlands, in rice and in irrigation waters are 16 times, two times and 160 times the soil, crop and water standards, respectively.
Similarly, cadmium contents in liver and meat of chicken and pork sampled in the affected areas as well as in fish sampled from adjacent ponds, are several orders of magnitude higher than maximum permissible levels in food stuff, posing a significant health risk to potential consumers. Tests on human blood, urine and hair collected from affected population also reveals high levels of cadmium relative to a control population. Human hair content in heavily affected zones is five times higher than background levels (i.e., 0.347 (g/g Vs. 0.067 (g/g); more troubling is that this concentration is only slightly lower than the threshold concentration that causes the Itai-itai disease in humans. Although, there is clear correlation between cadmium concentrations in fish and hair, contamination from non-dietary exposure could not be ruled out.
The high detection rate of pesticide residues in food stuff in Hubei has served to focus much public attention on these chemicals, out of concern to protect humans and other biota. A high percentage of pesticides applications in the province is for rice production, and pesticides residues are often detected at the point of application in paddy fields as spray drift from aerial spraying, runoff from rain, and drainage of paddy water. And despite their ban in 1984, organochlorine pesticides (e.g., dichloro diphenyl trichloroethane- DDT and 1,2,3,4,5,6-benzene hexachloro cyclohexane- BHC) are still detected in grains, vegetables, meat products, eggs and oil. Their continued presence is probably due to a combination of the persistent nature of organo-chlorine, and their continuing, albeit illegal, use by farmers.
Furthermore, because of the increasing use of organo-phosphates, such chemicals are increasingly detected in food stuff like vegetables, because the lag time between application and consumption is short, relative to rice grain. More than one third of flower ,leaf, root and fruit vegetables sampled from a typical agricultural village in QiangJiang county had detectable concentrations of organophosphates (i.e., methamidophos, Parathion-methyl, phoxim, malathion). Levels of methamidophos and phoxim exceeded the maximum residue concentration legally allowed in raw agricultural commodity. This finding is particularly disturbing, since organophosphates and synthetic pyrethroids have somewhat short persistence suggesting that farmers put their produce in the market right after spraying their field. The increase in areas devoted to vegetable production is likely to increase the population's dietary exposure, notwithstanding that individual farmers handling, mixing, loading or applying the chemical are most likely receiving the highest level of exposure.
As reliable monitoring, assessment and reporting procedures are put into place, there remains the need to ensure that appropriate environmental policies, laws and regulations are also developed and enforced.