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A cruise was conducted along the northwestern coast of Baja California, off the US-Mexico border region, to determine the physical, biological and anthropogenic factors affecting the concentration and distribution of phosphates (PO43-). The vertical distribution of temperature and PO43- showed isograms (13°C and 0.75 μM, respectively) rising towards the shore. Although this phenomenon was observed in all the study area, it was more abrupt in the southern part than in the northern, resulting in lower phosphate concentrations in the north (0.50 μM) associated with high chlorophyll a concentrations (10.0 mg m-3). A principal components analysis indicated that the PO43- concentrations were related to upwelling (51%) and phytoplankton biomass (23%). A PO43- mass balance indicated that sewage discharge had a very local effect, contributing 3.0 ± 0.12 t d-1 (5%), while horizontal advection contributed 20.0 ± 2.2 t d-1 (32%) and upwelling supply was 41.1 ± 2.3 t d-1 (63%). If the PO43- sewage contribution trend does not change, we predict that in 2035 the anthropogenic contribution will be as high as the amount delivered to the area by the Californian Current. Conversely, if Mexico's sewage treatment systems improve to a level similar to that in the USA, we estimate that by 2012 the anthropogenic sources will be insignificant. [ABSTRACT FROM AUTHOR]

From January, 1984 to March, 1999, 73 children under 15 y old (ages 1-14 y, median 9 y) were admitted after being bitten by snakes of the genus Bothrops. Twenty-six percent of the children were classified as mild envenoming, 50.7% as moderate envenoming and 20.6% as severe envenoming. Two patients (2.7%) showed no signs of envenoming. Most of the patients presented local manifestations, mainly edema (94.5%), pain (94.5%) ecchymosis (73.9%) and blisters (11%). Local and/or systemic bleeding was observed in 28.8% of the patients. Before antivenom (AV) administration, blood coagulation disorders were observed in 60.7% (incoagulable blood in 39.3%) of the 56 children that received AV only in our hospital. AV early reactions, most of which were considered mild, were observed in 44.6% of these cases (in 15/30 patients not pretreated and in 10/26 patients pretreated with hydrocortisone and histamine H1 and H2 antagonists). The main clinical complications observed were local infection (15.1%), compartment syndrome (4.1%), gangrene (1.4%) and acute renal failure (1.4%). No deaths were recorded. There were no significant differences with regard to severity of envenoming versus the frequency of blood coagulation disorders among the three categories of envenoming (p = 0.75) or in the frequency of patients with AV early reactions between the groups that were and were not pretreated (p = 0.55). The frequency of local infection was significantly greater in severe cases (p < 0.001). Patients admitted more than 6 h after the bite had a higher risk of developing severe envenoming (p = 0.04).