Naphthalene exerts substantial nontarget effects on soil nitrogen mineralization processes in a subalpine forest soil: A microcosm study

Abstract

Naphthalene has been widely used to test the functional roles of soil fauna, but its nontarget effects remain uncertain in various soils. To determine whether there is a potential nontarget effect on soil biochemical properties in subalpine forest soil, soils in a subalpine forest on the western Qinghai-Tibet Plateau were treated by naphthalene in microcosms. The responses of soil microbial activity and nutrients to naphthalene were studied following 52 days of incubation. The results showed that the naphthalene application obviously decreased the microbial respiration rate in the first 10 days of the incubation and then increased the rate in the following days of the incubation. Moreover, the naphthalene application did not significantly affect the microbial activities overall, measured as soil microbial phospholipid fatty acid (PLFA) abundances and biomasses, or most enzyme activities (invertase, nitrate reductase and nitrite reductase) during the whole incubation period. However, naphthalene suppressed increases in the DON, NH 4 + -N and NO 3 - -N contents and urease activity and led to the net mineralization of inorganic N (NH 4 + -N + NO 3 - -N), in contrast to the net immobilization result in the controls. These results suggest that naphthalene can exert direct nontarget effects on soil microbial respiration and N mineralization processes in subalpine soils. Caution should be taken when using naphthalene to repel soil animals in field experiments.

Non-target Effects of Naphthalene on the Soil Microbial Biomass and Bacterial Communities in the Subalpine Forests of Western China

“…As a result, bacteria grow rapidly when they obtain sufficient exogenous C from naphthalene. However, the results of laboratory simulation experiments indicate that naphthalene treatment does not significantly affect total bacterial, gram-positive bacterial, or gram-negative bacterial PLFA 32 , which is inconsistent with the findings of field research. The limitations of the microcosm control experiment and the lack of aboveground vegetation may be two reasons for the differences in experimental results 18,32 .…”

“…However, carbon and nutrients released upon microbial death can be rapidly accumulated and increased 35,36 . The effective matrix that is released can be used directly or indirectly by living organisms in the soil, resulting in an increased number of microorganisms 32,37 . On the other hand, soil bacterial populations are regulated by interactions with soil fauna 7 .…”

Delivery rate alters the effects of tire wear particles on soil microbial activities

“…In this study, the increase of β-1,4-N-acetyl-glucosaminidase activity (Fig. 1(c)), which may be abruptly caused by the release of chemical additives (PAHs and nitro-compounds as vulcanization agent) from TWPs [14,[35][36][37], was observed in the abrupt treatment, and this change might neutralize the negative effects on β-glucosidase activity in the abrupt treatment (Fig. 1(a)).…”

Delivery rate alters the effects of tire wear particles on soil microbial activities

“…The increase of β-1,4-N-acetyl-glucosaminidase activity (Fig. 1c) was observed in the abrupt treatment, and this may be abruptly caused by the release of chemical additives from TWPs such as nitro-compounds (vulcanization agent) and PAHs, and PAHs can increase nitrogen mineralization/transcripts with the changes in the functional gene abundance [15,[33][34][35].…”