Does the Geographic Difference of Soil Properties Matter for Setting Up the Soil Screening Levels in Large Countries Like China?

Abstract

China issued the unified national soil screening levels (NSSLs) in 2018 to assist the regulation of contaminated sites, but the applicability of NSSLs was not thoroughly evaluated. Datasets from the National Qinghai–Tibet Plateau Scientific Data Center indicated great variability of soil organic matter (0.8–173 g/kg), soil water content (0.05–0.6), soil porosity (0.4–0.6), and soil bulk density (1.11–1.59 kg/m3). We analyzed the effects of soil properties on the derivation of SSLs by using Monte Carlo simulations. The soil factors mainly affected the inhalation exposure pathway of volatile organic compounds (VOCs). They had an effect of more than two orders of magnitude on SSLs for most selected VOCs, particularly with the parameters 0.35 > Henry’s law constant > 0.1 and carbon–water distribution coefficient of >100. We compared NSSLs with the recommended SSLs assuming fifth percentile by using Monte Carlo simulations. In general, NSSLs were not sufficient to identify contaminated sites that require additional investigation in the south, central, and northwest regions but were too conservative in screening sites out that required no further action in the east and northeast regions. Our framework and findings may contribute to more scientific and effective soil quality management in other large countries.

Reciprocal Interactions of Abiotic and Biotic Dechlorination of Chloroethenes in Soil

“…3,4 In China, according to the National Soil Contamination Survey Bulletin published in 2014, around 16% of surveyed soil samples had at least one organic pollutant exceeding standard values, particularly the organohalide pollutants. 5 Similarly, an agricultural soil survey reported that volatile organohalides were present in all tested samples. Among them, chloroethenes (CEs) detection frequency ranged from 3.57 to 6.25%, with a concentration range from 0.9 to 3.61 ng/g.…”

“…14 CE attenuation. 15,16 However, the soil organic and mineral compositions, as well as their biophysiochemical properties, could be highly variable, e.g., organic matter (0.8−173 g/kg), water content (0.05−0.6 m 3 m −3 ), porosity (40−60%), and bulk density (1.11−1.59 kg/m 3 ), 5 posing challenges in understanding the major players and their specific roles in abiotic attenuation of organohalides. In addition to these abiotic compositions and processes, microorganisms also played critical roles in removing organohalides.…”

“…As a sink of various organic contaminants, soil could affect the fate of organic pollutants (e.g., organohalides) and their subsequent transport to other environmental matrices, including groundwater and atmosphere. , The fate of organic pollutants in soil was synergistically determined by combined biophysiochemical processes, including accumulation and transformation through sorption/desorption, abiotic degradation, and biotransformation, which highly depended on the soil compositions and physiochemical properties as well as soil microbiomes. , In China, according to the National Soil Contamination Survey Bulletin published in 2014, around 16% of surveyed soil samples had at least one organic pollutant exceeding standard values, particularly the organohalide pollutants . Similarly, an agricultural soil survey reported that volatile organohalides were present in all tested samples.…”

“…Mechanisms underlying the SOM adsorption of CEs included hydrogen bonding, electrostatic attraction, and pore-filling . Therefore, humic substances (e.g., humic acid and humin) as typical SOM generally function as electron mediators/carriers to improve CE attenuation. , However, the soil organic and mineral compositions, as well as their biophysiochemical properties, could be highly variable, e.g., organic matter (0.8–173 g/kg), water content (0.05–0.6 m 3 m –3 ), porosity (40–60%), and bulk density (1.11–1.59 kg/m 3 ), posing challenges in understanding the major players and their specific roles in abiotic attenuation of organohalides. In addition to these abiotic compositions and processes, microorganisms also played critical roles in removing organohalides .…”

Potential Risk Recognition of Agricultural Land Based on Agglomeration Characteristics of Pollution-Related Enterprises: A Case Study on the Black Soil Region in Northeast China

“…Numerous studies on soil pollution source analyses have shown that industrial and mining enterprise sewage disposal activity has become the main source of soil pollution and risk in China [9][10][11][12]. According to the 2014 national survey report on soil contamination, the soil exceedance rate around industrial and mining enterprises was 36.3%, which was much higher than that of the total samples throughout China (16.1%) [13][14][15]. Soil contamination was particularly prominent in some regions, such as the northeastern old industrial base [16,17].…”