The present study is a systematic corpus-based investigation of the domain-specific multiword units
(henceforth MWUs) in marine accident investigation reports (henceforth MAIR), with a view to
characterizing their most prominent syntactic, semantic and functional features.
To achieve these principal objectives, the target MWUs were first identified by applying a new
approach, which incorporates the notion of ‘meaning’ into statistical-based measures. This method
ensures the domain-specific MWU extraction to the largest extent and provides valid data for the
subsequent analysis. Through proposing a three-dimensional analytical framework, this study has
obtained the following findings:
First, the domain-specific MWUs are largely composed of two-word sequences, while the occurrences
of 4- and 5-word MWUs are relatively rare. Among all the target MWUs, only 1.10% of the expressions
occur very commonly within the genre (˚1,000 times). By contrast, the majority of the expressions
(70.97%) occur with the frequency less than 100 times. The skewed distribution indicates that MAIR
genre tends to employ a wide variety of domain-specific MWUs rather than repetition of a
small number of common expressions.
Second, in terms of the syntactic features of the domain-specific MWUs, NP structure is the most
commonly employed grammatical type. The abundant use of this structure implies that the
domain-specific meaning of MAIR genre is largely carried in the nominal group. Apart from NP structure, there is also a marked prevalence of VP structures among the domain-specific MWUs in MAIR genre and these MWUs present structural variation. Of all the VP-based patterns, the ‘verb phrase with active verb’ pattern stands out since it incorporates a large number of action verbs, which are used to describe the actions done by people. The wide use of these phrases implies that MAIR genre tends to highlight the people’s
roles during the accidents, with particular attention to the information about what or who caused or performed the activity. Similarly, PP structures were also frequently adopted by the domain-specific MWUs, especially the pattern beginning with preposition of. This pattern was mostly used to specify possessions. It thus can be inferred that the information that provided in MAIR genre tends to be concrete and specific.
Third, by conducting a functional analysis of the target MWUs, it was found that the primary function of the domain-specific MWUs is to express referential meanings and contribute to the thematic development. Furthermore, due to their multifunctional nature, some referential MWUs also perform the function of stance and discourse organizing. When expressing stance, most MWUs express impersonal epistemic stance, with the purpose of minimizing the imposition of the reporters’ opinions. Other word sequences appear to be deontic in nature, as they are mainly realized by the MWUs incorporating with require or modal verbs. The primary function of these MWUs is to set out the obligations and issue suggestions for the agents according to certain norms and regulations. When functioning as discourse organizer, the domain-specific MWUs usually adopt the pattern of ‘that-clause controlled by main verbs in active voice’ to introduce the topics.
Unlikely, when using for elaborating the topics, they tend to clarify the logical relationships, especially the causative-resultative relation, rather than providing additional information in MAIR genre.
Fourth, the distinctive semantic features of the domain-specific MWUs can be best reflected when
these MWUs perform the functions of activity identification and specification. For instance, most
domain-specific MWUs used for describing activities are of general nature, but they convey
specialized meaning in MAIR genre. Similarly, when domain-specific MWUs are used to provide tangible or intangible frames for specifying certain attributes, the use of these MWUs in MAIR genre is significantly deviant from their use in general English register.
In all, by gaining insights into the salient features of the domain-specific MWUs in MAIR genre,
the present study may make contributions and implications in the following aspects: the
construction of extraction method for domain-specific MWUs, the compilation of maritime-specific
MWU list, the teaching and learning of maritime English, especially the maritime-specific MWUs, and
providing reference for writing MAIR to the experts who are from non-native English speaking