Seasonal variations of nitrate dual isotopes in wet deposition in a tropical city in China

Chen, Fajin; Lao, Qibin; Jia, Guodong; Chen, Chunqing; Zhu, Qingmei; Zhou, Xin

doi:10.1016/j.atmosenv.2018.09.061

Cited by 59 publications

(36 citation statements)

References 37 publications

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“…The average value on the cruise was much higher than that in aerosol samples (Xiao et al, ) or rainwater observed at Yongxing Island (Table ). It was also much higher than previously reported δ 15 N‐NO 3 − values for Chinese mainland and coastal cities (Chen et al, ; Fang et al, ) or for Bermuda in the Atlantic (Altieri et al, ).…”

Section: Resultscontrasting

confidence: 56%

Enhanced Primary Production in the Oligotrophic South China Sea Related to Southeast Asian Forest Fires

et al. 2020

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Atmospheric reactive nitrogen deposition is an important process in the nitrogen cycle of natural ecosystems, especially in oligotrophic oceans. Increased land‐based atmospheric nitrogen deposition over the ocean changes the stoichiometric balance of marine ecosystems; this causes changes in ecosystem functions and biogeochemical cycles. Current studies have shown that atmospheric reactive nitrogen is mainly derived from land‐based human activities, such as the use of fertilizers, combustion of fossil fuels, and forest fires. Forest fires can provide a vast amount of reactive nitrogen and other nutrients over short time scales and may greatly influence marine ecosystems. Here, we document a large change in nitrogen concentration and primary productivity in upper levels of the South China Sea (SCS), coincident with Indonesian forest fires between August and September of 2012. Using back trajectories, fire spot maps, geographical distributions of the smoke, vertical distributions of the depolarization ratio, and nitrogen isotope values of nitrate in rainwater, we found that the change in nitrogen could be attributed to the forest fires. Our results show that the SCS received about 180 Gg of N as wet deposition during the sampling period. This atmospheric nitrogen deposition caused high primary productivity (40.679 ± 15.852 mg C·m−2·hr−1) in the upper levels of the SCS, which tripled values recorded in other years. This suggests that high nitrogen levels as well as other nutrients derived from tropical Asian forest fires are of great importance to the marine ecosystem of the SCS and also likely affect global marine biogeochemical cycles.

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Section: Resultscontrasting

confidence: 56%

Enhanced Primary Production in the Oligotrophic South China Sea Related to Southeast Asian Forest Fires

et al. 2020

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“…However, in summer, NH 4 + and PO 4 3− concentrations decreased gradually from the upper bay to the bay mouth, the concentrations were higher than those in winter, thereby suggesting that the nutrients that originated from the upper bay affected the mid-bay and the bay mouth under the heavy discharge during the wet season. In addition, the decreasing trend of δ 15 values were low (<0‰) in the coastal area, and some values of dual NO 3 − isotopes in the seawater from the bay during summer were also close to the range of NO 3 − in precipitation [20,36,37].…”

Section: Biological Processes Of No 3 − In Zhanjiang Baymentioning

confidence: 81%

“…Zhanjiang Bay is a monsoon-controlled bay with significant precipitation under southwest-heading monsoon in the spring and summer months. Heavy rainfall in the bay usually occurs in fall and summer (accounting for 75% of the yearly rainfall), while the dry season usually occurs in winter and spring [20]. Sampling was conducted in summer (June 2017) and winter (December 2017).…”

Section: Field Samplingmentioning

confidence: 99%

Assessing Seasonal Nitrate Contamination by Nitrate Dual Isotopes in a Monsoon-Controlled Bay with Intensive Human Activities in South China

Cao

Lao

et al. 2020

IJERPH

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Nitrate (NO3−) dual isotope analysis was performed in Zhanjiang Bay, which is a closed bay with intensive human activities in South China, to investigate seasonal changes in the main NO3− sources and their biogeochemical processes in the monsoon-controlled climate. The relatively low N/P ratios in Zhanjiang Bay suggests that nitrogen (N) is a limiting nutrient, which indicates that the increase of N is favorable for phytoplankton proliferation. However, a sufficient amount of ammonium was found in our study area owing to intensive human activities, which can support biological processes. Thus, less NO3− biological processes were found, indicating that NO3− isotopic characteristics may reveal details of the mixing from various sources. The Bayesian mixing model showed that NO3− in the upper bay originated from manure (43%), soil N (30%), N fertilizer (17%), and N precipitation (10%) during winter, which reflects the local human activities; while NO3- sources during summer were mainly N fertilizer (36%), soil N (32%), and manure (31%), indicating the source as the runoff from the upper river basin. Our results suggest that nitrate dual-isotope was very useful for tracing the main NO3− sources in the condition of the sufficient ammonium, and runoff exerted an important impact on the shift in NO3− sources between both the local source and the source from the upper river basin during the two seasons in this monsoon-controlled bay.

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“…In addition, due to a relatively closed area in the inner bay, it is easier to accumulate organic matter emitted by local activity. In Zhanjiang City, the rainy season begins mainly in April, and rainfall increases significantly during that month [29]. During the sampling period in this study, heavy rainfall led to a relatively huge transport of organic matter from the local city into the bay, where organic matter could have been remineralised easily-due, perhaps, to the priming effect [30] to NH 4 + and its subsequent nitrification to NO 3 − in the water column.…”

Section: Strong Decomposition Occurred In the Inner Baymentioning

confidence: 83%

Analysis of Dissolved Oxygen and Nutrients in Zhanjiang Bay and the Adjacent Sea Area in Spring

Zhong

Chen

et al. 2020

Sustainability

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As a semi-closed bay with narrow bay mouths, the distribution of nutrients in Zhanjiang Bay was different from bays with open bay mouths and rivers with large flows. It is important to study the water quality of Zhanjiang Bay to determine the impact of human activities on this semi-closed bay. Based on field survey data in spring, the spatial distribution of nutrients and other physico-chemical parameters was investigated, in order to study the geochemical characteristics of nutrients in semi-closed bays. Higher nutrient concentrations were observed in the inner and outer bays, but lower concentrations were observed at the bay mouth. With other analyses of physico-chemical parameters, the higher nutrient concentrations in the inner bay originated mainly from the diluted freshwater input from local developments and rivers. With the strong flow that exists along the western coast of Guangdong Province, the higher dissolved inorganic nitrogen (DIN) and SiO3–Si concentrations along the outer bay may be influenced by discharge from local cities in western Guangdong Province. There was stronger phytoplankton assimilation at the bay mouth, which resulted in reduced nutrient concentrations in this area. Although the hydrographic characteristics between the inner bay and outer bay were significantly different, the distribution of chlorophyll-a (Chla) levels was similar. However, we found significantly low dissolved oxygen (DO) and high apparent oxygen utilisation (AOU) consumption levels in the inner bay, and high DO and low AOU levels in the outer bay, which suggested that decomposition was more important than photosynthesis in the closed bay, even in spring during the phytoplankton bloom.

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Seasonal variations of nitrate dual isotopes in wet deposition in a tropical city in China

Cited by 59 publications

References 37 publications

Enhanced Primary Production in the Oligotrophic South China Sea Related to Southeast Asian Forest Fires

Enhanced Primary Production in the Oligotrophic South China Sea Related to Southeast Asian Forest Fires

Assessing Seasonal Nitrate Contamination by Nitrate Dual Isotopes in a Monsoon-Controlled Bay with Intensive Human Activities in South China

Analysis of Dissolved Oxygen and Nutrients in Zhanjiang Bay and the Adjacent Sea Area in Spring

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