Agricultural crop

Proposed mercury criteria for crop protection (Table 19.1) include 0.2 xg/L in irrigation water, and 0.2- 0.5mg/kg DW in soils of several countries, although higher levels are allowable in cropland soils of New 

Jersey ( 1.0mg/kg DW) and the Former Soviet Union ( 2.1 mg/kg DW). Sludge and other wastes applied to European soils should contain 1.5 mg Hg/kg, but higher levels of 10.0-25.0 mg Hg/kg are permissible in solid wastes applied to agricultural soils of Iowa, Maine, Vermont, and California (Table 19.1). 

The significance of elevated mercury residues in tissues of aquatic organisms is not fully understood. Induction of liver metalloth-ioneins and increased translatability of MRNA are biochemical indicators of the response of fish to mercury exposure, and more research is recommended on this and other indicators of mercury stress. Concentrations exceeding 

More research is also needed on mercury removal technology. In the Florida Everglades, for example, using prototype wetlands of 1545 ha, removal of agricultural nutrients from stormwater reduced total mercury and methylmercury concentrations in water by as much as 70% in the first 2 years of operation moreover, total mercury concentrations in largemouth bass were about 0.1 mg Hg/kg FW muscle throughout the project site vs. 0.5 mg Hg/kg FW in adjacent areas. 

Tissue residues of mercury, as methylmercury, considered harmful to adult birds ranged between 8.0mg/kg FW in brain to 15.0 in 

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Agricultural crops Agricultural residues Agriculturaluse Agncultural uses Agn culture... 

Careful estimates suggest that the total losses to agricultural crops from insect attacks in the United States average about 10% of production and amount to more than 14 biUion annually (1). Worldwide agricultural losses from insect attacks have been estimated as about 14% of production (2). 

Table 2. Quantities of Pesticides Most Commonly Used in U.S. Agricultural Crop Production in 1995 ...

Linear alkylbenzenesulfonate showed no deleterious effect on agricultural crops exposed to this material (54,55). Kinetics of biodegradation have been studied in both wastewater treatment systems and natural degradation systems (48,57,58). Studies have concluded that linear alkylbenzenesulfonate does not pose a risk to the environment (50). Linear alkylbenzenesulfonate has a half-life of approximately one day in sewage sludge and natural water sources and a half-life of one to three weeks in soils. Aquatic environmental safety assessment has also shown that the material does not pose a hazard to the aquatic environment (56). 

U.S. Dept, of Agriculture, Crops in Peace and War Government Printing Office, Washington, D.C., 1950. 

Fig. 1. United States agricultural crop markets for manufactured controlled release fertilizers, 1990. (a) Total percentage ( 14 million) of market value by crop and (b) total percentage (6,800 t) of consumption by product type. IBDU is isobutyUdene diurea PCF, polymer-coated fertilizer UF,...

POLYON-coated products are marketed for turf and commercial nursery appHcations and specialty, medium to high cost, agricultural crop appHcations. 

U. Gupta, "Copper in Agricultural Crops," inj. O. Nriagu, ed., Copperin the Environment, Part l,John Wiley Sons, Inc., New York, 1979. 

However, the fertilizing effect of nitrates (and sulfates) may be counterbalanced by the leaching of potassium, magnesium, calcium, and other nutrients from forest soils. There is little evidence that agricultural crops are being injured by exposures to nitrates in precipitation. The amount of nitrates in rainwater is almost always... 

Recombinant DNA technology now verges on the ability to engineer at will the genetic constitution of organisms for desired ends. The commercial production of therapeutic biomolecules in microbial cultures is already established (for example, the production of human insulin in quantity in E. coli cells). Agricultural crops with desired attributes, such as enhanced resistance to her-... 

The natural supply of nitrogen available to plants from the nitrogen cycle is limited. To meet the growing demands for agriculture crops, nitrogen is added to soil in the form of fertilizers. An estimated one-third of the human population is fed as a result of the use of synthetic fertilizers. 

The number of reports about hemicelluloses that have been covered by this review indicates the significantly increased importance of all types of hemicelluloses as plant constituents and isolated polymers during the last decade. Attention has been paid not only to known hemicelluloses but also to the primary structure, physicochemical, physical, and various functional properties of hemicelluloses isolated from hitherto uninvestigated plants. The efforts to exploit a variety of plant as potential sources of hemicelluloses were pointed out particularly for agricultural crops, wood wastes, as well as for by-products of pulp and rayon fiber technologies. Many studies were devoted to characterize seed-storage hemicelluloses from plants that have been traditionally applied in food and medicine of many underdeveloped countries to find substitutes for imported commercial food giuns. 

Experimental exposure of several agricultural crops to ambient levels of acidic pollutants has not established measurable yield responses although foliar damage has been observed. Complex interactions with other airborne pollutants, particularly ozone, makes it difficult to exactly establish the damages that may be attributed to acidic deposition 14), It has not been possible to establish any critical level of acidic deposition in relation to crop damages. 

Agricultural crops, effect of acidification, 52 Agricultural productivity, biocides-net productivity relationship, 307-308 Agricultural technologies, changes, 311,313 Airborne contaminants, description, 135 Airborne pollutant, definition, 135 Air pollutants, classifications, 66 Air pollution effects, 166,167r scope, 21-22 sources, 165-166 state, 4... 

The effect of water salinity on crop growth is largely of osmotic nature. Osmotic pressure is related to the total salt concentration rather than the concentration of individual ionic elements. Salinity is commonly expressed as the electric conductivity of the irrigation water. Salt concentration can be determined by Total Dissolved Solids (TDS) or by Electrical Conductivity (EC). Under a water scarcity condition, salt tolerance of agricultural crops will be the primordial parameter when the quality of irrigation water is implicated for the integrated water resources management [10]. 

Table 1 shows the relative salt tolerances of agricultural crops. These data serve as a guide to the relative tolerance among crops to adapt the quahty of water to crops patterns under water scarcity. It is important to highlight that absolute tolerances vary with climate, soil conditions, and cultural practices. 

Table 1 Relative salt tolerance of agricultural crops [12]...

For all natural waters, boron is one of their constituents with varying concentrations from minute traces to several ppm (parts per million). It is essential for plant growth but is exceedingly toxic at concentration slightly above optimum. Boron tolerances vary depending upon climate, and crop varieties. Relative boron tolerances of agricultural crops are presented in Table 3 [12]. 

It is illegal to use methyl parathion indoors. Methyl parathion is approved only for use on agricultural crops. In 1999, EPA canceled the use of methyl parathion on many food crops. 

Residue amounts of methyl parathion have been detected in air, water, fish, soil, and agricultural crops consumed as foods. 

Methyl parathion has been released to the environment mainly as a result of its use as an insecticide on crops. It is applied to agricultural crops by aerial or ground spraying equipment. Methyl parathion has been detected in surface waters and sediments, rainwater, aquatic organisms, and food. There are no known natural sources of the compound. Methyl parathion has been identified in at least 16 of the 1,585 hazardous waste sites on the NPL (HazDat 2001). 

Methyl parathion is only for use on agricultural crops. The reports that methyl parathion has been illegally/improperly used inside homes to kill insects (ATSDR 1999 EPA 1999b) show that people in homes that are sprayed with methyl parathion may be exposed to dangerously high levels of methyl parathion. 

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