Temporal trends analysis to assess water quality parameters in the Houston ship channel


1993 1993 Nov 14


Crocker PA
Society of Environmental Toxicology and Chemistry PU

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A temporal trends analysis on Houston Ship Channel monitoring data contained in the EPA STORET data base was conducted using the SAS CORR procedure. Pearson Product Moment, Spearmants Ranked Order and Kendall's tau-b correlations were made between time and 21 ambient water and six sediment quality data collected over a 10-20 year period. Apparent trends were assumed at a probability (P) greater than or equal to 95%, and possible trends were assumed at P greater than or equal to 90%. A dichotomy was observed with average pollutant concentrations: levels were much greater in the upstream industrialized portion of the Channel (Turning Basin), and decreased dramatically downstream, except for selenium which had an opposite pattern. Organic carbon, suspended solids, fecal coliforms' ammonia, phosphate, total arsenic and total copper in water are decreasing with time at all or most of the five station evaluated. By contrast, nitrate and nitrite concentrations are increasing at all or most stations. Biological oxygen demand, dissolved oxygen and Kjeldahl nitrogen are improving at upstream stations, with stable or reversing trends near the mouth of the Channel. Metals in bottom sediment are decreasing dramatically at the Turning Basin and are relatively stable over time at downstream stations. Temporal trends analysis of conventional and toxic parameters was found to be a useful water quality assessment and management tool. (DBO)




Arsenic, dissolved oxygen, Monitoring, Pollutants, Q5 01503 Characteristics,behavior and fate, Resource management, Selenium, Toxicology, USA, Water analysis, Water quality