Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Reactive Particle-tracking Solutions to a Benchmark Problem on Heavy
  Metal Cycling in Lake Sediments
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga