. Bulletin. Science. WTP1 WTP2(n=4) Tec(n=10) MV(n=5) Big Pipe (n=7) Toll Bridge (n=8) Site Fig. 2. Levels of dissolved and particulate cadmium (Cd), copper (Cu) and lead (Pb) in Tecate Creek/Alamar River; n denotes the number of samples taken at each site. Levels of disolved Cd are so low (< |JLg/L) that they do not show in the this figure. of the organic and nutrient loads could be responsible for the appearance of some higher-demanding macroinvertebrate organisms especially at the last site on the Rio Alamar (Table 3). Nitrification seems to be nearly totally absent, probably because
. Bulletin. Science. WTP1 WTP2(n=4) Tec(n=10) MV(n=5) Big Pipe (n=7) Toll Bridge (n=8) Site Fig. 2. Levels of dissolved and particulate cadmium (Cd), copper (Cu) and lead (Pb) in Tecate Creek/Alamar River; n denotes the number of samples taken at each site. Levels of disolved Cd are so low (< |JLg/L) that they do not show in the this figure. of the organic and nutrient loads could be responsible for the appearance of some higher-demanding macroinvertebrate organisms especially at the last site on the Rio Alamar (Table 3). Nitrification seems to be nearly totally absent, probably because of the high organic carbon levels in the water which leads to the dominance of heterotrophic bacteria and suppresses the development of nitrifying organisms (Table 4). Mean- while, the decrease of total coliform densities remains moderate, with an 87% (110 X 103 MPN/100 mL km) removal efficiency; while fecal coliforms are re- duced (69 X 103 MPN/100 mL km) with a rather high efficiency of For most metals, there was a significant loss of the particulate (as well as the dissolved) fraction, as the water moved downstream in Tecate Creek to the Rio Alamar (Figures 2-3). Surprisingly, for Cu, Cr, and Ni, the highest levels observed among all of the sampled sites was actually at WTP1 (this site upstream of the discharge point for the Tecate Municipal Wastewater Treatment Plant), where levels of these metals were 98, 345, and 518 |JLg/L, respectively. It should be 350 Dissolved Cr Particulate Cr Dissolved Ni Particulate Ni Dissolved Zn Particulate Zn. WTP1 (n=5) WTP2(n=4) Tec(n=10) MV(n=5) Big Pipe (n=7) Toll Bridge (n=8) Site Fig. 3. Levels of dissolved and particulate chromium (Cr), nickel (Ni) and zinc (Pb) in Tecate Creek/Alamar River; n denotes the number of samples taken at each Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfec
Size: 2480px × 1007px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectscience
