人类活动影响下的龙口海岸带海底地下水排泄通量研究

doi:10.13745/j.esf.sf.2022.2.71

摘要/Abstract

摘要：

在沿海地区,以²²³Ra和²²⁴Ra为示踪剂建立的镭质量平衡模型已广泛应用于海底地下水排泄量(SGD)的研究中,然而目前国内外关于在人类活动复杂影响较大情况下的SGD研究却极为少见。本文对比研究了在有防渗墙(A区)和填海造陆(B区)两种不同人为因素影响下的龙口海岸带水体表现年龄、海底地下水排泄量及其携带的氮磷营养盐通量。结果表明,A区平均水体表现年龄为14.26 d,B区平均水体表现年龄为10.64 d。此外,B区沿岸地下水以及近岸海水中的Ra活度均普遍高于A区,而盐度低于A区。在SGD方面,A区的SGD速率为1.26~1.60 cm·d^-1,B区为1.43~1.82 cm·d^-1,考虑SGD在评估方法上存在一定的误差,因此两个区域的SGD速率相差不大。但与我国其他自然海域相比,这两个区域的SGD速率均处于较低水平。此外,B区的氮磷营养盐浓度普遍高于A区,而且由SGD驱动的氮磷营养盐通量不同,地下水输入的不平衡的营养盐极易改变龙口海域的营养盐结构,对海洋生态环境产生不利影响,这也进一步证实SGD在沿海生态环境以及水体污染治理中的重要地位。

关键词: 海底地下水排泄, 水体表现年龄, 镭同位素, 氮磷营养盐, 人类活动

Abstract:

The radium mass balance model based on ²²³Ra and ²²⁴Ra tracers has been widely used in the study of submarine groundwater discharge (SGD) in coastal zones. However, few researches are currently done to study the influence of human activities on SGD. In this paper, the water residence time, SGD flux and nutrient flux carried by SGD were compared between the Longkou coastal zones A and B, under the influence of two different human activities, namely an impervious dam in Zone A and land reclamation in Zone B. Results showed that the average water residence time in Zone A was 14.26 days and in Zone B 10.64 days. In addition, radium activities in groundwater and seawater in Zone B were generally higher than that in Zone A; whereas salinities were lower in Zone B than in Zone A. The discharge rates for SGD in Zone A ranged from 1.26 to 1.60 cm/d and in Zone B from 1.43 to 1.82 cm/d. Therefore the discharge rates for SGD in these two zones were comparable within the margin of error. However, the discharge rates for SGD were relatively low in these two zones compared to other natural coastal areas in the country. Moreover, the nitrogen and phosphorus nutrient concentrations in Zone B were generally higher than that in Zone A. The nitrogen and phosphorus nutrient fluxes carried by SGD were different in the two zones. Such unbalanced nutrient inputs from SGD could easily change the nutrient structure of the Longkou coastal zones, which has an adverse impact on the marine ecological environment, further confirming that SGD is important for coastal ecological environment and water pollution control.

Key words: submarine groundwater discharge, residence time, radium isotopes, nitrogen and phosphorus nutrients, human activities

中图分类号:

郭巧娜, 赵岳, 周志芳, 林锦, 戴云峰, 李孟军. 人类活动影响下的龙口海岸带海底地下水排泄通量研究[J]. 地学前缘, 2022, 29(4): 468-479.

GUO Qiaona, ZHAO Yue, ZHOU Zhifang, LIN Jin, DAI Yunfeng, LI Mengjun. Submarine groundwater discharge in Longkou coastal zones under the influence of human activities[J]. Earth Science Frontiers, 2022, 29(4): 468-479.

图/表 8

图1 龙口海岸带及研究海域位置,海水、地下水取样点的布置

Fig.1 Geographical location of Longkou coastal area and distribution of sampling sites in the study area

表1 海水、地下水中镭同位素活度、盐度等数据

Table 1 Radium activity and salinity data for seawater and groundwater samples

取样	经度/(°)	纬度/(°)	盐度w(NaCl)/‰	²²³Ra活度/(dpm·hL^-1)	²²⁴Ra活度/(dpm·hL^-1)	²²⁴Ra/²²³Ra AR
S1	120.47	37.83	31.30	1.39±0.17	18.11±1.27	13.03±1.56
S2	120.35	37.78	34.40	2.06±0.25	40.16±2.81	19.50±2.06
S3	120.27	37.74	33.70	2.2±0.26	29.74±2.08	13.52±1.58
S4	120.20	37.70	33.30	1.22±0.15	25.9±1.81	21.23±2.19
S5	120.12	37.66	32.10	3.22±0.40	-	-
S6	120.04	37.72	33.50	1.27±0.15	21.27±1.49	17.32±1.85
S7	120.14	37.77	33.40	-	-	-
S8	120.22	37.82	33.30	2.7±0.32	33.15±2.32	12.28±1.48
S9	120.32	37.86	34.90	1.4±0.17	18.44±1.29	13.17±1.56
S10	120.44	37.89	34.60	1.27±0.07	15.32±1.07	12.06±1.17
S11	120.42	37.96	36.50	1.14±0.14	16.9±1.18	14.82±1.7
S12	120.28	37.92	33.70	1.06±0.13	14.98±1.05	14.13±1.65
S13	120.17	37.88	33.60	1.96±0.23	31.89±2.23	16.27±1.79
S14	120.08	37.83	33.40	1.62±0.19	25.94±1.82	16.01±1.77
S15	119.99	37.77	32.50	1.48±0.18	20.66±1.45	13.96±1.63
S16	119.92	37.83	32.90	1.65±0.2	17.52±1.23	10.62±1.36
S17	120.03	37.89	32.10	0.78±0.09	22.64±1.59	29.03±2.74
S18	120.14	37.94	35.20	2.08±0.25	27.51±1.93	13.23±1.57
S19	120.25	37.99	34.30	0.83±0.1	16.06±1.12	19.35±2.04
S20	120.40	38.03	34.50	1.15±0.14	5.62±0.39	4.89±0.84
GW1	120.33	37.65	30.20	-	-
GW2	120.25	37.55	33.10	32.98±3.96	1 528.41±106.99
GW3	120.39	37.69	29.80	10.19±1.22	1 011.75±70.82
GW4	120.32	37.67	34.50	40.23±4.83	2 028.05±141.96
GW5	120.34	37.69	33.10	38.47±4.61	1 975.74±138.30
GW6	120.43	37.73	31.20	8.77±1.05	544.23±38.096

图2 (a)海水盐度图;(b)表层海水中223Ra活度图;(c)表层海水中224Ra活度图

Fig.2 Contour maps of salinity (a) and 223Ra (b) and 224Ra (c) activities in the sea area of Longkou City

图3 (a) 地下水中镭同位素与盐度关系;(b)A区海水中镭同位素与盐度关系;(c)B区海水中镭同位素与盐度关系

Fig.3 Relationships between radium activity and salinity in groundwater (a) and seawater in Zone A (b) and Zone B (c)

表2 研究区海水和地下水中氮磷营养盐浓度

Table 2 Nitrogen and phosphorus nutrient contents in seawater and groundwater of the study area

营养盐	分区	地下水营养盐浓度/ (mg·L^-1)		海水营养盐浓度/ (mg·L^-1)
营养盐	分区	范围	均值	范围	均值
DIP	A区	0.10~0.12	0.11	0.04~0.09	0.06
DIP	B区	0.05~0.23	0.11	0.05~0.10	0.08
$NO 3 -$	A区	0.58~20.00	10.29	0.09~0.15	0.11
$NO 3 -$	B区	0.01~2.66	1.09	0.10~0.74	0.40
$NO 2 -$	A区	0.05~0.34	0.20	0.02~0.05	0.03
$NO 2 -$	B区	0.004~0.12	0.10	0.03~0.07	0.04

表2 研究区海水和地下水中氮磷营养盐浓度

Table 2 Nitrogen and phosphorus nutrient contents in seawater and groundwater of the study area

营养盐	分区	地下水营养盐浓度/ (mg·L^-1)		海水营养盐浓度/ (mg·L^-1)
营养盐	分区	范围	均值	范围	均值
DIP	A区	0.10~0.12	0.11	0.04~0.09	0.06
DIP	B区	0.05~0.23	0.11	0.05~0.10	0.08
$NO 3 -$	A区	0.58~20.00	10.29	0.09~0.15	0.11
$NO 3 -$	B区	0.01~2.66	1.09	0.10~0.74	0.40
$NO 2 -$	A区	0.05~0.34	0.20	0.02~0.05	0.03
$NO 2 -$	B区	0.004~0.12	0.10	0.03~0.07	0.04

图4 (a)地下水中营养盐浓度;(b)海水中营养盐浓度

Fig.4 Nutrient concentrations in groundwater (a) and seawater (b) samples

表3 SFGD和SGD计算所需参数

Table 3 Parameters for SFGD and SGD calculations

参数	符号	A区取值	B区取值	单位
面积	A_bay	3.92×10⁸	1.05×10⁹	m²
体积	V_bay	3.22×10⁹	8.87×10⁹	m³
水体表现年龄	t	11.14~21.87	5.90~13.75	d
盐度总量	M_s	1.10×10¹¹	2.97×10¹¹
²²⁴Ra地下水端员值	²²⁴Ra_gw	544.23	1 635.99	dpm/ (100 L)
²²⁴Ra外海水背景值	²²⁴Ra_sea	10.84	16.79	dpm/ (100 L)
外海盐度值	S_s	34.40	33.60	‰
蒸发量	E_T	3.39	3.39	mm·d^-1
降雨量	P_T	1.75	1.75	mm·d^-1

表4 我国不同研究区域海底地下水排泄速率

Table 4 SGD rates in different study areas in China

研究区域	方法	SGD排泄速度/ (cm·d^-1)	文献
渤海湾	²²³Ra,²²⁸Ra	1.98~4.78	[50]
黄河	Ra,²²²Rn	4.50~13.90	[30]
大亚湾	²²³Ra,²²⁴Ra,²²⁶Ra,²²⁸Ra	4.83~6.01	[51]
本文	²²³Ra,²²⁴Ra	1.90~2.57 1.42~1.81

参考文献 51

[1]	BURNETT W C, BOKUNIEWICZ H, HUETTEL M, et al. Groundwater and pore water inputs to the coastal zone[J]. Biogeochemistry, 2003, 66: 3-33.
[2]	ZHANG Y, LI H L, XIAO K, et al. Improving estimation of submarine groundwater discharge using radium and radon tracers: application in Jiaozhou Bay, China[J]. Journal of Geophysical Research: Oceans, 2017, 122(10): 8263-8277.
[3]	ZHANG Y, SANTOS I R, LI H L, et al. Submarine groundwater discharge drives coastal water quality and nutrient budgets at small and large scales[J]. Geochimica et Cosmochimica Acta, 2020, 290: 201-215.
[4]	WANG X J, LI H L, ZHANG Y, et al. Investigation of submarine groundwater discharge and associated nutrient inputs into Laizhou Bay (China) using radium quartet[J]. Marine Pollution Bulletin, 2020, 157: 111359.
[5]	LI L, BARRY D A, STAGNITTI F, et al. Submarine groundwater discharge and associated chemical input to a coastal sea[J]. Water Resources Research, 1999, 35(11): 3253-3259.
[6]	MOORE W S. Fifteen years experience in measuring Ra-224 and Ra-223 by delayed-coincidence counting[J]. Marine Chemistry, 2008, 109(3/4): 188-197.
[7]	李海龙, 王学静. 海底地下水排泄研究回顾与进展[J]. 地球科学进展, 2015, 30(6): 636-646.
[8]	BURNETT W C, AGGARWAL P K, AURELI A, et al. Quantifying submarine groundwater discharge in the coastal zone via multiple methods[J]. Science of the Total Environment, 2006, 367(2/3): 498-543.
[9]	XU B C, BURNETT W, DIMOVA N, et al. Hydrodynamics in the yellow river estuary via radium isotopes: ecological perspectives[J]. Continental Shelf Research, 2013, 66: 19-28.
[10]	WANG Q Q, LI H L, ZHANG Y, et al. Submarine groundwater discharge and its implication for nutrient budgets in the western Bohai Bay, China[J]. Journal of Environmental Radioactivity, 2020, 212, 106132.
[11]	DULAIOVA H, BUMETT W C. Evaluation of the flushing rates of Apalachicola Bay, Florida via natural geochemical tracers[J]. Marine Chemistry, 2008, 109: 395-408.
[12]	RABALAIS N N, TURNER R E, JUSTIC D, et al. Nutrient changes in the Mississippi River and system responses on the adjacent continental shelf[J]. Estuaries, 1996, 19(2): 386-407.
[13]	CHUNG S Y, SENAPATHI V, PARK K H, et al. Source and remediation for heavy metals of soils at an iron mine of Ulsan City, Korea[J]. Arabian Journal of Geosciences, 2018, 11(24): 769-790.
[14]	ZHOU Y Q, BEFUS K M, SAWYER A H, et al. Opportunities and challenges in computing fresh groundwater discharge to continental coastlines: a multimodel comparison for the United States Gulf and Atlantic Coasts[J]. Water Resources Research, 2018, 54(10): 8363-8380.
[15]	LUO X, JIAO J J, MOORE W S, et al. Submarine groundwater discharge estimation in an urbanized embayment in Hong Kong via short-lived radium isotopes and its implication of nutrient loadings and primary production[J]. Marine Pollution Bulletin, 2014, 82(1/2): 144-154.
[16]	LUO X, JIAO J J. Submarine groundwater discharge and nutrient loadings in Tolo Harbor, Hong Kong using multiple geotracer-based models, and their implications of red tide outbreaks[J]. Water Research, 2016, 102: 11-31.
[17]	MOORE W S, BLANTON J O, JOYE S B. Estimates of flushing times, submarine groundwater discharge, and nutrient fluxes to Okatee Estuary, South Carolina[J]. Journal of Geophysical Research, 2006, 111(C9): C09006.
[18]	POST V E A, GROEN J, KOOI H, et al. Offshore fresh groundwater reserves as a global phenomenon[J]. Nature, 2013, 504(7478): 71-78.
[19]	HUGHES A L H, WILSON A M, MOORE W S. Groundwater transport and radium variability in coastal porewaters[J]. Estuarine, Coastal and Shelf Science, 2015, 164: 94-104.
[20]	DEBNATH P, MUKHERJEE A. Quantification of tidally-influenced seasonal groundwater discharge to the Bay of Bengal by seepage meter study[J]. Journal of Hydrology, 2016, 537: 106-116.
[21]	PRAKASH R, SRINIVASAMOORTHY K, GOPINATH S, et al. Measurement of submarine groundwater discharge using diverse methods in Coleroon Estuary, Tamil Nadu, India[J]. Applied Water Science, 2018, 8(1): 1-13.
[22]	GUO Q N, LI H L. Terrestrial-originated submarine groundwater discharge through deep multilayered aquifer systems beneath the seafloor[J]. Hydrological Processes, 2015, 29(2): 295-309.
[23]	VAERET L, LEIJNSE A, CUAMBA F, et al. Holocene dynamics of the salt-fresh groundwater interface under a sand island, Inhaca, Mozambique[J]. Quaternary International, 2012, 257: 74-82.
[24]	GOPINATH S, SRINIVASAMOORTHY K, SARAVANAN K, et al. Modeling saline water intrusion in Nagapattinam coastal aquifers, Tamilnadu, India[J]. Modeling Earth Systems and Environment, 2016, 2(2): 1-10.
[25]	GOPINATH S, SRINIVASAMOORTHY K, SARAVANAN K, et al. Characterizing groundwater quality and seawater intrusion in coastal aquifers of Nagapattinam and Karaikal, South India using hydrogeochemistry and modeling techniques[J]. Human and Ecological Risk Assessment, 2019, 25(1/2): 314-334.
[26]	MOORE W S. Large groundwater inputs to coastal waters revealed by ²²⁶Ra enrichments[J]. Nature, 1996, 380(6575): 612-614.
[27]	SANTOS I R, PETERSON R N, EYRE B D, et al. Significant lateral inputs of fresh groundwater into a stratified tropical estuary: evidence from radon and radium isotopes[J]. Marine Chemistry, 2010, 121(1/2/3/4): 37-48.
[28]	SADAT-NOORI M, SANTOS I R, SANDERS C J, et al. Groundwater discharge into an estuary using spatially distributed radon time series and radium isotopes[J]. Journal of Hydrology, 2015, 528: 703-719.
[29]	RODELLAS V, GARCIA-ORELLANA J, TREZZI G, et al. Using the radium quartet to quantify submarine groundwater discharge and porewater exchange[J]. Geochimica et Cosmochimica Acta, 2017, 196: 58-73.
[30]	PETERSON R N, BURNETT W C, TANIGUCHI M, et al. Radon and radium isotope assessment of submarine groundwater discharge in the Yellow River delta, China[J]. Journal of Geophysical Research, 2008, 113(C9).
[31]	GARCIA-ORELLANA J, COCHRAN J K, BOKUNIEWICZ H, et al. Evaluation of Ra-224 as a tracer for submarine groundwater discharge in Long Island Sound (NY)[J]. Geochimica et Cosmochimica Acta, 2014, 141: 314-330.
[32]	WANG X J, ZHANG Y, LUO M H, et al. Radium and nitrogen isotopes tracing fluxes and sources of submarine groundwater discharge driven nitrate in an urbanized coastal area[J]. Science of the Total Environment, 2021, 763: 144616.
[33]	MOORE W S. Ages of continental shelf waters determined from ²²³Ra and ²²⁴Ra[J]. Journal of Geophysical Research: Oceans, 2000, 105(C9): 22117-22122.
[34]	MOORE W S, BLANTON J O, JOYE S B. Estimates of flushing times, submarine groundwater discharge, and nutrient fluxes to Okatee Estuary, South Carolina[J]. Journal of Geophysical Research, 2006, 111(C09): C09006.
[35]	ZHANG Y, LI H L, WANG X J, et al. Estimation of submarine groundwater discharge and associated nutrient fluxes in eastern Laizhou Bay, China using ²²²Rn[J]. Journal of Hydrology, 2016, 533: 103-113.
[36]	KIM G, RYU J W, YANG H S, et al. Submarine ground-water discharge (SGD) into the Yellow Sea revealed by Ra-228 and Ra-226 isotopes: implications for global silicate fluxes[J]. Earth and Planetary Science Letter, 2005, 237(1/2): 156-166.
[37]	MOORE W S. Seasonal distribution and flux of radium isotopes on the southeastern US continental shelf[J]. Journal of Geophysical Research, 2007, 112(C10): C10013.
[38]	LEE C M, JIAO J J, LUO X, et al. Estimation of submarine groundwater discharge and associated nutrient fluxes in Tolo Harbour, Hong Kong[J]. Science of the Total Environment, 2012, 433: 427-433.
[39]	RODELLAS V, GARCIA-ORELLANA J, MASQUE P, et al. Submarine groundwater discharge as a major source of nutrients to the Mediterranean Sea[J]. Proceedings of the National Academy of Sciences of the United States of America, 2015, 112(13): 3926-3930.
[40]	SLOMP C P, VAN CAPPELLEN P. Nutrient inputs to the coastal ocean through submarine groundwater discharge: controls and potential impact[J]. Journal of Hydrology, 2004, 295(1/2/3/4): 64-86.
[41]	TANIGUCHI M, STIEGLITZ T, ISHITOBI T. Temporal variability of water quality of submarine groundwater discharge in Ubatuba, Brazil[J]. Estuarine, Coastal and Shelf Science, 2008, 76(3): 484-492.
[42]	MAKINGS U, SANTOS I R, MAHER D T, et al. Importance of budgets for estimating the input of groundwater derived nutrients to an eutrophic tidal river and estuary[J]. Estuarine, Coastal and Shelf Science, 2014, 143: 65-76.
[43]	GARRISON G H, GLENN C R, MCMURTRY G M. Measurement of submarine groundwater discharge in Kahana Bay, O’ahu, Hawai’i[J]. Limnology and Oceanography, 2003, 48(2): 920-928.
[44]	HU C, MULLER-KARGER F E, SWARZENSKI P W. Hurricanes, submarine groundwater discharge and Florida’s red tides[J]. Geophysical Research Letters, 2006, 33(11).
[45]	LI D Y, WU Y X, GAO E K, et al. Simulation of seawater intrusion area using feedforward neural network in Longkou, China[J]. Network Weekly News, 2020, 12(8): 2107.
[46]	WU J C, MENG F H, WANG X W, et al. The development and control of the seawater intrusion in the eastern coastal of Laizhou Bay, China[J]. Environmental Geology, 2008, 54(8): 1763-1770.
[47]	LI X J, CHEN L L, ZHOU Z Q, et al. Spatio-temporal variation of subtidal macrobenthic fauna and the ecological assessment of Longkou Artificial Island construction in Bohai Sea, China[J]. Journal of Oceanology and Limnology, 2019, 38(6): 1811-1824.
[48]	TANG G Q, YI L X, LIU L L, et al. Factors influencing the distribution of Ra-223 and Ra-224 in the coastal waters off Tanggu and Qikou in Bohai bay[J]. Continental Shelf Research, 2015, 109: 177-187.
[49]	DOUGLAS A R, MURGULET D, PETERSON R N. Submarine groundwater discharge in an anthropogenically disturbed, semi-arid estuary[J]. Journal of Hydrology, 2020, 580: 124369.
[50]	WANG Q Q, LI H L, ZHANG Y, et al. Evaluations of submarine groundwater discharge and associated heavy metal fluxes in Bohai Bay, China[J]. Science of the Total Environment, 2019, 695: 133873.
[51]	张萌. 大亚湾海底地下水排泄及营养盐和重金属通量的评估[D]. 北京: 中国地质大学(北京), 2017.