|
Fig. 1.
Sampling points of the study areas from the Qinghai-Tibetan Plateau (the
in-set
blue area is the whole QTP).
Fig. 2.
Concentration of PTEs (mg/g) in the grassland (GL:
a
) and farmland (FL:
b
) soils of Hongyuan (HY), Tianzhu (TZ), Shandan (SD), Nierong (NR), and Maqu
(MQ). In Fig. a, the standards used for HY, NR, and MQ are based on soil pH
>
7.5, while for TZ and SD is from 6.5 to 7.5 as presented in
Table 1
and
Table S1
;
correlation of metals with environmental factors in GL (
c
) and FL (
d
) soils. *OM
=
Organic matter, Temp
=
Temperature, Precip
=
Precipitation, PD
=
Population
density, NA: Not Available (the permissible limit for Fe was not available).
Fig. 3.
Abundance of MPs in the grassland (GL) and farmland (FL) soils of the studied areas (
a
); comparison of average MPs abundance in our study with other
eastern QTP studies (
b
); correlation of MPs with environmental variables in GL (
c
) and FL (
d
).*MP conc
=
MPs concentration, OM
=
Organic matter,
Temp
=
Temperature, Precip
=
Precipitation, PD
=
Population density.
Fig. 4.
Graphs showing the characteristics of microplastics in the grassland (GL) and farmland (FL) soils. (
a
) shapes; (
b
) colors (dual color: black-grey/black-white);
(
c
) polymer types.
*
PES
=
Polyester; CA
=
Cellulose acetate, Uni
=
Unidentified; PET
=
Polyethylene terephthalate; PP
=
Polypropylene; PE
=
Polyethylene; HY
=
Hon
gyuan; TZ
=
Tianzhu; SD
=
Shandan; NR
=
Nierong; MQ
=
Maqu.
Fig. 5.
Concentration and type of PTEs adsorbed by different polymers as compared to soil background concentration of PTEs. (
a
) Hongyuan grassland; (
b
) Hon
gyuan farmland; (
c
) Tianzhu grassland; (
d
) Tianzhu farmland; (
e
) Shandan grassland (PE was not included due to inadequate sample); (
f
) Shandan farmland, (
g
)
Nierong grassland; (
h
) Maqu grassland. *Un
=
Unidentified.
Fig. 6.
Risk assessment of microplastic polymers (MPs) and potentially toxic elements (PTEs) in the grasslands and farmlands. (
a
) Pollution Load Index of PTEs; (
b
)
Potential Ecological Risk Index of PTEs; (
c
) Pollution Load Index of MPs; (
d
) Potential Ecological Risk Index of MPs.
*
MQ
=
Maqu; NR
=
Nierong; SD
=
Shandan (CA was
excluded due to unavailability of its toxicity score); TZ
=
Tianzhu; HY
=
Hongyuan; CL
=
Contamination Level; RL
=
Risk Level. The dotted lines indicate the limits of
pollution levels based on
Table S3
.
Fig. 7.
Potential ecological risk index (TRI) from each studied PTE in the GL (
a
) and FL (
b
) locations (HY
=
Hongyuan; TZ
=
Tianzhu; SD
=
Shandan; NR
=
Nierong;
MQ
=
Maqu). The colored horizontal dotted lines denote the limit of risk levels (RL) based on
Table S5
.
Fig. 8.
Potential ecological risk indexes (TRI and SRI) from each identified MP polymer (CA was excluded due to unavailability of its toxicity score) and shape in the
GL (
a and b
) and FL (
c and d
) locations (HY
=
Hongyuan; TZ
=
Tianzhu; SD
=
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