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Across 3. usually due to inherent dispersion of samples collected from a population defined statistically by variance or standard deviation about a true value 5. an action or series of actions involving physical, chemical or biological entities 7. sludge produced in individual on-site wastewater disposal systems, such as septic tanks 10. temporal scale covering a period greater than 10,000 years 12. a set of pollution standard index of air quality to protect public health, safety and general welfare 14. interdependence of elements within specific environmental systems, and the interactions between different types of systems 15. portion of rainfall or irrigation water that flows across the ground surface and is eventually returned to streams 17. pollutants from a known source which is discharged into a body of water or land 18. involves physical removal of samples from the environment 19. this is how data will be compared with reference values when known 20. refers to the number of measurements or observations 21. air pollutants with national air quality standards that define allowable concentrations of these substances in ambient air 22. specific aspect or quality of a measurement such as color, size or chemical concentration 23. spatial scale covering an area of greater than 100 Km but less than 10,000 Km 24. done in cases where the substitution of one measurement is possible for another at a reduced costs 25. measures the approximate concentration of dissolved oxygen required by bacteria or micro-organisms to decompose organic matter in waste water or surface water

Down 1. atmospheric particles with diameters equal to or less than 100 micrometers 2. any vehicle propelled by or through combustion of carbon-based or other fuel, constructed and operated principally for the conveyance of persons and transportation of property or goods 4. refers to any building or immobile structure, facility or installation which emits or may emit any air pollutant and may be defined generally as individual points of air emission 6. source of air emissions that is not confined to a discrete point or points of emissions 8. observation and study of the environment 9. third dimension of space comprising of altitudes or depths 11. defined as the general amount of pollution present in a broad area, and refers to the atmosphere's average purity as distinguished from discharge measurement taken at the source of pollution 13. this is where you discuss the specific variances and overall variances of the data or dataset 16. component of environmental monitoring which aims to collect and analyze a subset of samples that represent the target environment in space and time