Environmental Engineering Reference
In-Depth Information
Group
Period
1
2
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1
2
Key
1
H
He
Actinides
Nonmetals
Halogens
Noble gases
Alkali metals
Alkaline earth metals
Transition metals
Metalloid
Lanthanides
1.008
4.003
3
4
5
6
7
8
9
10
2
Li
Be
B
C
N
O
F
Ne
6.941
9.012
10.81
12.01
14.01
16.00
19.00
20.18
11
12
13
14
15
16
17
18
Na
Mg
Al
Si
P
S
Cl
Ar
22.99
24.31
26.98
28.09
30.97
32.07
35.45
39.95
19
K
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
4
39.10
40.08
44.96
47.88
50.94
52.00
54.94
55.85
58.93
58.69
63.55
65.39
69.72
72.64
74.92
78.96
79.90
83.79
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Ag
Cd
In
Sn
Sb
Te
I
Xe
5
Pd
85.47
87.62
88.91
91.22
92.91
95.94
(98)
101.1
102.9
106.40
107.9
112.4
114.8
118.7
121.8
127.6
126.9
131.3
55
56
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
Cs
Ba
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
6
'
132.9
137.3
178.5
180.9
183.9
186.2
190.2
192.2
195.10
197.0
200.5
204.4
207.2
209.0
(209)
(210)
(222)
87
88
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
''
Fr
Ra
Rf
Db
Sg
Bh
Hs
Mt
Ds
Rg
Cn
Uut
Uug
Uup
Uuh
Uus
Uuo
7
(223)
(226)
(261)
(262)
(266)
(264)
(277)
(268)
(281)
(272)
(285)
(286)
(289)
(289)
(291)
(294)
(294)
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
138.9
140.1
140.9
144.2
(145)
150.4
152
157.2
158.9
162.5
164.9
167.3
168.9
173.0
175.0
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
Ac
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr
(227)
232
231
238
(237)
(244)
(243)
(247)
(247)
(251)
(252)
(257)
(258)
(259)
(262)
FIGURE 5.5 Periodic table of elements. An element's reactivity—determined in part by its chemical structure
and hence position within the periodic table—is important in element cycling because it affects reactions within
cycles and variety of forms an element will take as it moves among different pools in an ecosystem. (From http://
periodic.lanl.gov/index.shtml .)
ecosystems. The ecological importance of multiple oxidation states is illustrated by both
carbon and nitrogen, and stands in contrast to phosphorus, as will be seen in the following
chapters.
MOVE, STICK, AND CHANGE: A SIMPLE
FRAMEWORK FOR ELEMENTAL CYCLING
Much of the complexity of various element cycles and the movement and fate of materi-
als in ecosystems can be encompassed by a simple three-part framework: move, stick, and
change. Ecosystem scientists frequently ask what controls the movement of materials within
or between pools or what mechanisms result in materials sticking within systems. The bal-
ance between these mechanisms will determine whether systems are gaining, losing, or in
steady-state with respect to the material of interest. Understanding transformations—
changes in materials from one chemical state or form to another—is also very important
since an entity's state will often determine whether it moves or sticks.
Material moves both within and between systems. For example, carbon dioxide can
move both through mixing within a lake and by flux from lake to atmosphere. Soil erosion
can be described in terms of loss from a field or movement downstream in a river. In any
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