USGS - Science for a changing world

Table 1. Concentrations of selected constituents, San Marcos Springs, San Marcos, Texas, July–August 1994

[mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, degrees Celsius; mg/L, milligrams per liter; --, no data; <, less than detection limit; mg/L, micrograms per liter]

Selected properties and major ions

Site 1

Site 2

Site 3

Site 4

Specific conductance (mS/cm)

588

589

582

608

pH (standard units)

    7.8

    7.5

    7.6

     7.7

Temperature (C)

  23

  22.5

  23

  23.5

Dissolved oxygen (mg/L)

    8.8

    8

    8.6

    8.3

Calcium, dissolved (mg/L)

  86

  86

  82

  86

Magnesium, dissolved (mg/L)

  17

  17

  16

  17

Sodium, dissolved (mg/L)

  11

  11

  11

  16

Potassium, dissolved (mg/L)

    1.4

    3.3

    1.3

    1.9

Sulfate, dissolved (mg/L)

  23

  24

  23

  26

Chloride, dissolved (mg/L)

  19

  18

  19

  24

Fluoride, dissolved (mg/L)

      .2

      .2

      .2

      .2

Silica, dissolved (mg/L)

  11

   11

  11

  11

Dissolved solids, sum of constituents (mg/L)

328

331

310

344

 

 

 

 

 

Nutrients (mg/L)

 

 

 

 

Nitrogen, nitrate, dissolved

--

--

--

    1.76

Nitrogen, nitrite, dissolved

     <.01

    <.01

    <.01

      .04

Nitrogen, ammonia, dissolved

       .03

      .03

      .04

      .08

Nitrogen, total

     1.2

    1.2

    1.1

    1.8

Phosphorus, dissolved

     <.01

    <.01

      .03

      .13

Phosphate, ortho, dissolved

       .03

--

      .03

      .34

 

 

 

 

 

Trace elements (mg/L)

 

 

 

 

Arsenic, dissolved

  <1

  <1

    1

  <1

Barium, dissolved

  36

  37

  35

  35

Cadmium, dissolved

    1

 <1.0

  <1.0

  <1.0

Chromium, dissolved

  <5

  <5

  <5

  <5

Copper, dissolved

<10

<10

<10

<10

Iron, dissolved

  <3

  <3

  <3

    4

Lead, dissolved

<10

  20

<10

  20

Manganese, dissolved

    1

    3

    5

    4

Mercury, dissolved

   <.1

 <.1

    <.1

 <.1

Nickel, dissolved

<10

<10

<10

<10

Selenium, dissolved

  <1

 <1

  <1

  <1

Silver, dissolved

  <1.0

 <1.0

  <1.0

 <1.0

Strontium, dissolved

540

540

520

540

Zinc, dissolved

  <3

  <3

  <3

  <3

Back to:

Observations